The physical and insecticidal durability of two dual active ingredient nets (Interceptor® G2 and Royal Guard®) in Benin, West Africa; results for a durability study embedded in a cluster randomised controlled trial

The physical and insecticidal durability of two dual active ingredient nets (Interceptor® G2 and Royal Guard®) in Benin, West Africa; results for a durability study embedded in a cluster randomised controlled trial | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Research Article The physical and insecticidal durability of two dual active ingredient nets (Interceptor® G2 and Royal Guard®) in Benin, West Africa; results for a durability study embedded in a cluster randomised controlled trial Corine Ngufor, Josias Fagbohoun, Augustin Fongnikin, Juniace Ahoga, and 13 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-4782261/v1 This work is licensed under a CC BY 4.0 License Status: Published Journal Publication published 07 Oct, 2024 Read the published version in Parasites & Vectors → Version 1 posted 14 You are reading this latest preprint version Abstract Background: Studies evaluating the physical and insecticidal durability of dual active ingredient (AI) insecticide-treated nets (ITNs) are essential for making programmatic decisions for their deployment. We performed a prospective study embedded in a cluster randomised controlled trial (cRCT) to evaluate the attrition, fabric integrity, and insecticidal durability of Interceptor® G2 (alpha-cypermethrin-chlorfenapyr) and Royal Guard® (alphacypermethrin-pyriproxyfen), compared to Interceptor® (alpha-cypermethrin) in Benin. Methods A total of 2,428 study nets in 1,093 randomly selected households in 5 clusters per arm of cRCT were monitored for ITN attrition and fabric integrity every 6–12 months post-distribution. Householders were further surveyed to investigate non-study net use and their preference for ITN fabric types used in the study nets. A second cohort 120 nets per ITN type withdrawn every 12 months were assessed for chemical content and insecticidal activity in laboratory bioassays. Alpha-cypermethrin bioefficacy was investigated in WHO cone bioassays and tunnel tests using susceptible Anopheles gambiae Kisumu while chlorfenapyr and pyriproxyfen bioefficacy were investigated using the pyrethroid resistant An coluzzii Akron strain. Chlorfenapyr bioefficacy was assessed in tunnel tests while pyriproxyfen activity was assessed in cone bioassays as the reduction in fertility of blood-fed survivors using ovary dissection. Bioefficacy was expressed as the proportion of ITNs passing predetermined criteria i.e knock-down ≥ 95% or 24hrs mortality ≥ 80% or reduction in fertility ≥ 50%. Results Overall ITN survivorship was 52% at 24 months and reduced to 15% at 36 months. Median ITN survival time was lower with Royal Guard® relative to Interceptor® (1.6 years vs . 2.3 years HR = 1.49, 95% CI = 1.36–1.66, p < 0.001) and Interceptor® G2 (1.6 years vs 2.1 years; HR = 1.33, 95% CI = 1.20–1.47, p < 0.001). Householders overwhelmingly preferred polyester nets relative to polyethylene nets (96%) and more Royal Guard® nets were replaced with spare polyester nets from previous campaigns. All Royal Guard® nets passed efficacy criteria for alphacypermethrin at all time points (100%) while ITN pass rates after 24 months had reduced to < 40% for pyriproxyfen and chlorfenapyr. The chemical content analysis showed a higher loss rate of the non-pyrethroid insecticides relative to the pyrethroids in each dual AI ITN; 74% vs 47% for Royal Guard® and 85% vs 63% for Interceptor® G2 at 36 months. Conclusion The median ITN survival time for Interceptor® G2 (2.1 years) and Royal Guard® (1.6 years) in Benin is substantially lower than the 3 years. Royal Guard® nets were discarded more quickly by householders partly due to their low preference for polyethylene nets. The insecticidal activity of the non-pyrethroid insecticides in both dual AI ITNs was short-lived compared to alpha-cypermethrin. The results corroborate the findings from the cRCT in Benin. Durability attrition fabric integrity bioefficacy Insecticide Treated Net pyriproxyfen chlorfenapyr alpha-cypermethrin dual active ingredients Interceptor® Interceptor® G2 Royal Guard® Figures Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Figure 7 Background The large-scale deployment of insecticide-treated nets (ITNs) via tri-annual mass campaigns is the main malaria prevention and control strategy deployed in most endemic countries in sub-Saharan Africa. While ITNs have played a major role in reducing the burden of malaria globally [ 1 ], their impact is threatened by their poor retention and use by householders, poor durability of the fabric and insecticide applied to them and the development of vector resistance to pyrethroids – the main insecticide used on ITNs [ 2 ]. To optimize the impact of ITNs for malaria control, high levels of coverage of the target communities must be achieved, householders must retain and use them, and the nets should maintain their efficacy against mosquito vectors until the next campaign cycle [ 3 ]. By contrast, several studies have shown that ITNs are discarded more quickly than the 3 years presumed by country policies with most endemic African countries showing a median ITN retention time of < 2 years [ 4 ]. ITN retention rates vary widely from one community to another driven by several factors including the durability of the fabric, usage patterns and perceived efficacy by householders [ 5 ]. To help inform programmatic decision-making for procurements and replacement of worn-out nets, the WHO has established guidelines for investigating the durability of ITNs under operational conditions [ 6 ]. After distribution, ITNs are followed longitudinally to investigate their survivorship, fabric integrity and insecticidal activity using well-defined procedures. Several studies have reported poor entomological performance of pyrethroid-only ITNs in areas where vectors are resistant to pyrethroids. Dual active ingredient nets treated with a mixture of a pyrethroid and a non-pyrethroid compound capable of providing enhanced control of pyrethroid-resistant vectors were recently developed to help mitigate this threat. Nets treated with pyrethroids and the pyrrole chlorfenapyr or the insect growth regulator pyriproxyfen were endorsed by the WHO in 2023 [ 7 ] after demonstrating improved public health value over 2 years of use in cRCT across Africa [ 8 , 9 ]. Based on the findings from these trials, the WHO issued a strong recommendation for the deployment of pyrethroid-chlorfenapyr ITNs and a conditional recommendation for the deployment of pyrethroid-pyriproxyfen nets instead of pyrethroid-only nets in areas of pyrethroid resistance [ 7 ]. Following this endorsement, the proportion of these nets deployed in SSA is projected to increase substantially with pyrethroid-chlorfenapyr nets potentially replacing pyrethroid-only nets [ 10 ]. As the uptake of dual active ingredient nets increases, studies monitoring their durability should be performed in different settings to inform decision-making for their procurement and replacement by control programmes. WHO guidelines for assessing the attrition, fabric integrity, chemical content and insecticidal durability of ITNs under operational use [ 11 , 12 ] were initially developed when pyrethroids were the only insecticides applied on ITNs and are being updated to cover new dual AI ITNs. This includes identifying standardised high throughput methods and suitable mosquito strains for testing the insecticidal durability of non-pyrethroid insecticides like chlorfenapyr and pyriproxyfen on nets. Unlike pyrethroids that knockdown and kill mosquitoes, chlorfenapyr is a pyrrole insecticide that acts on the insect mitochondria to slowly induce death [ 13 ] while pyriproxyfen is an insect growth regulator that sterilises adult female mosquitoes leading to a substantial reduction in offspring [ 14 , 15 ]. Like most malaria-endemic African countries, many ITN brands show poor durability in Benin. Indeed, a recent statistical inference study reported a low median ITN retention rate of ~ 1.4 years for Benin, among the bottom six of the forty malaria-endemic African countries included in the study [ 4 ]. To investigate the durability of dual active ingredient nets in Benin, we nested a prospective cohort study in a cRCTs conducted in the Zou region of the country between 2020 and 2023 to compare the durability of a pyrethroid chlorfenapyr ITN (Interceptor® G2) and a pyrethroid-pyriproxyfen ITN (Royal Guard) to a pyrethroid-only ITN (Interceptor). We marked two cohorts of nets at baseline in 10 clusters in each arm of the cRCT and surveyed them every 6–12 months to assess ITN attrition rate, fabric integrity, insecticidal efficacy and chemical content over 3 years of household use. Materials and methods Study area The ITN durability study was performed in the Cove, Zagnanado, and Ouinhi Districts (COZO), of the Zou department of central Benin (7°11′N 1°59′E) between March 2020 and November 2023. The study was nested in a cRCT evaluating the efficacy of dual active ingredient nets for the control of clinical malaria compared to a pyrethroid-only net [ 16 , 17 ]. The study area consisted of 123 villages with approximately 54,000 households and a population size of 220,000 inhabitants. It has two rainy seasons (May-July and September-November) though malaria transmission occurs year-round. A baseline survey performed in 2019 prior to the cRCT showed a high malaria infection prevalence of 43.5% despite high ITN use (96%) [ 18 ]. The vector population consists of both Anopheles gambiae and Anopheles coluzzii and is characterized by a high intensity of resistance to pyrethroids and susceptibility to chlorfenapyr and pyriproxyfen [ 19 ]. The main economic activities carried out by the population are agriculture, fishing, hunting, trade, and hospitality. Study arms Three different ITN types consisting of the 3 arms of the cRCT were evaluated in the durability study; two dual active ingredient nets (Interceptor® G2 and Royal Guard®) were compared to a standard pyrethroid-only ITN (Interceptor®). A description of the specifications of the three ITN types is provided below: Interceptor® G2 (BASF AGRO B.V.), is a WHO-prequalified 100-denier, polyester ITN coated with a mixture of alpha-cypermethrin and chlorfenapyr at target concentrations of 100 mg/m 2 (± 25%) and 200 mg/m 2 (± 25%) respectively. The bursting strength of the fabric is ≥ 405 kPa while the mass per unit area is 40 g/m² (± 10%) for 100 denier yarn. Royal Guard® (Disease Control Technologies, LLC, USA), is a WHO-prequalified 150-denier, polyethylene ITN incorporated with a mixture of alpha-cypermethrin and pyriproxyfen at target concentrations of 225 mg/m 2 (± 25%) and 225 mg/m 2 (± 25%) respectively. The bursting strength of the fabric is ≥ 450 kPa while the mass per unit area is 45 g/m² (± 10%) for 150 denier yarn. Interceptor® (BASF AGRO B.V.), is a WHO-prequalified 100-denier, polyester ITN coated with alpha-cypermethrin at target concentrations of 200 mg/m 2 (± 25%). The bursting strength of the fabric is ≥ 405 kPa while the mass per unit area is 40 g/m² (± 10%) for 100 denier yarn. Interceptor® is the control arm of the trial against which Interceptor® G2 and Royal Guard® are compared. Study design The study design has been described in detail previously [ 17 ]. Participating households were blinded to the type of ITN they received while field data collectors were blinded to the allocation of households to study arms. Ten out of 20 clusters of each study arm of the cRCT were randomly selected for the durability assessment (Fig. 1 ). Following ITN distribution, households were visited in these clusters to recruit and prospectively follow 2 separate cohorts of ITNs per arm (Cohorts 1 and 2) every 6–12 months to monitor their physical and insecticidal durability over 36 months. Cohort 1 consisted of a total of 2,428 nets from 348–391 randomly selected households in 5 clusters per study arm. These nets were followed for ITN survivorship and fabric integrity at 6-, 12-, 24-, 30- and 36 months post ITN distribution. Cohort 2 consisted of 1860 nets per study arm from 593 households from all 10 randomly selected clusters (~ 60 households per cluster) per study arm that were withdrawn (and replaced with new nets) for assessment of insecticidal activity in laboratory bioassays and experimental hut trials, the content of each active ingredient and for other studies. Cohort 1 and Cohort 2 nets received separate identification numbers and were sampled from different households to prevent the risk of destructive sampling of nets intended for ITN survivorship studies (cohort 1). Household sensitisation and marking of study nets ITNs were recruited for the durability study in the first month after ITN distribution from selected clusters of each arm of the cRCT using the ITN distribution list of the trial. Field workers visited selected households for each cohort of ITNs to mark study nets available in them. Using a wash-resistant marker, a unique code was written on the study net to indicate the study arm, cluster ID, household ID and the cohort to which it belonged. During this visit, the study team explained the durability study to the householders in their local language and assisted them in hanging up their nets if needed. Only nets that were hung up and in use at the start of the trial were included. The GPS coordinates and characteristics of each household included in the durability assessment were also recorded. ITN attrition and fabric integrity (cohort 1) Households in cohort 1 were visited at 6-, 12-, 24- and 36-months post ITN distribution and nets were assessed for attrition and fabric integrity at each time point. Attrition was assessed by recording the physical presence/absence of each net that was recruited in the household. Where a net was not found, the householder was asked about the reason for the loss of the net e.g given away, sold, stolen, worn out and disposed of etc. Attrition was classified into 3 categories; a) due to physical damage (wear and tear), b) due to the net being removed (given away, stolen, sold or used in another location) and c) due to the net being used for other purposes (repurposed). Nets that had never been used were recorded and excluded from the analysis. At each time point, all available cohort 1 ITNs of each type were assessed for fabric integrity (hole index) and condition. A minimum of 250 nets were assessed and to ensure this number, cohort 2 nets were also assessed for fabric integrity when available cohort 1 nets were insufficient. The survey team inspected the nets outside in broad daylight to determine the hole index using a portable frame over which the net was draped during the inspection. The nets were returned to the family right after the inspection. The number of holes and hole sizes on each ITN panel was measured using hole assessment sheets and classified into 4 sizes (size 1: 0.5-2cm, Size 2: 2–10 cm, Size 3: 10-25cm, and size 4: >25cm). Physical integrity was measured as the proportionate hole index (pHI) which was calculated as pHI = (1 × number of size 1 holes) + (23 × number of size 2 holes) + (196 × number of size 3 holes) + (576 × number of size 4 holes). Nets were then categorized based on recommended cut-off points for pHI into “good” condition (pHI 0–64), “acceptable” condition (pHI 65–642) and “torn” (pHI 643+) defined in WHO guidelines [ 12 ]. To determine the proportion of study nets that were in active use at each time point, we recorded the proportion of nets that were found hanging over sleeping places during each survey. Previous studies in Benin have indicated that householders usually have spare new ITNs from previous campaigns or routine distribution channels in their possession (unpublished data) which may affect the frequency with which the study nets are discarded. At 24 months, 362 participating households that had lost their study nets were further surveyed to identify the number, type and sources of non-study nets that they had replaced their study nets with. Householders were also administered a short questionnaire to determine what ITN fabric texture type (polyester vs. polyethylene) they preferred and to provide reasons why. They were shown examples of the two ITN fabric types and allowed to touch them before providing their responses. ITN bioefficacy and chemical analysis (cohort 2) For each ITN type a total of 120 nets belonging to cohort 2 were randomly selected and destructively sampled from households at 6, 12, 24 and 36-months post-distribution for laboratory and chemical analysis (Table 1 ). They were replaced with new nets of the same type at each sampling point. Thirty nets of each ITN type withdrawn at each timepoint were subjected to laboratory bioassays (WHO cone bioassays and tunnel tests where necessary) to monitor entomological efficacy against mosquito vectors and to chemical analysis to monitor changes in alphacypermethrin, chlorfenapyr and pyriproxyfen content. Four to five net pieces measuring 30x30cm cut from each ITN were tested in laboratory bioassays. A similar number of net pieces were obtained from adjacent positions to those for laboratory bioassays and preserved at 4 0 C for chemical analysis. Table 1 Number of Interceptor® G2, Royal Guard® and Interceptor® ITNs tested for bioefficacy and chemical content Months post ITN distribution No. of ITNs tested in lab bioassays No. of pieces per ITN Total number of pieces for bioassays No. of pieces for chemical analysis a 0 30 5 150 150 12 30 4 120 120 24 30 4 120 120 36 30 4 200 120 Total 120 590 510 a Net pieces preserved for chemical analysis were obtained from adjacent positions on the same ITNs cut for bioassays. Mosquito strains for laboratory bioassays Cone bioassays and tunnel tests were performed to monitor the bioefficacy of each AI in each ITN brand using laboratory-reared susceptible and pyrethroid-resistant strains of Anopheles gambiae s.l.. All strains were maintained at CREC/LSHTM insectary in Cotonou, Benin. The characteristic of each strain is described below. An. gambiae sensu stricto Kisumu, an insecticide-susceptible reference strain originating from the Kisumu area in Kenya and was colonised at the CREC/LSHTM insectary. An. coluzzii Akron, a pyrethroid and carbamate resistant strain originating from Akron (9°19′N2°18′E), Southern Benin, and maintained at CREC/LSHTM insectary. Resistance is mediated by target site mutations (L1014F kdr and Ace-1R ) and overexpressed cytochrome P450 enzymes [ 20 ]. WHO susceptibility bioassays were performed during each round of bioassays to confirm the susceptibility status of each mosquito strain to the insecticides used on the nets. At each time point, approximately 100 mosquitoes of each strain were exposed in batches of 25 in WHO bottle bioassays treated with alpha-cypermethrin (0.05%), chlorfenapyr (100µg) and pyriproxyfen (100µg). For alpha-cypermethrin and chlorfenapyr unfed 2–5 days-old mosquitoes were exposed for 1 hour and mortality was recorded after 24h for alpha-cypemethrin and 72h after exposure to chlorfenapyr. For pyriproxyfen, blood-fed 5–8 days old mosquitoes were exposed for 1 hour in treated bottles and survivors were dissected 3 days later to measure the proportional reduction in fertility relative to the control unexposed mosquitoes as described previously [ 21 ]. The bioassays were performed at a temperature of 27°C ± 2°C and a relative humidity of 75% ± 10%. Laboratory bioassay methods In line with the existing WHO guidelines [ 6 , 12 ], ITN bioefficacy at each timepoint was expressed in terms of the proportion of ITNs passing pre-determined efficacy criteria for each active ingredient in cone bioassays or tunnel tests. Table S1 summarises the methods and strains used to assess the efficacy of each active ingredient in each ITN type. All bioassays were performed at 27 ± 2°C and 75% ± 10% relative humidity. Bioefficacy of alphacypermethrin in Interceptor® and Royal Guard® Following WHO guidelines for testing the durability of the bioefficacy of pyrethroid-treated ITNs, the efficacy of alpha-cypermethrin in Interceptor® and Royal Guard® was monitored in 3-minute cone bioassays using unfed 3–5 days old mosquitoes of the susceptible An gambiae Kisumu strain. At each time point, 40–50 mosquitoes were exposed to each ITN in replicates of ~ 5 mosquitoes per cone and 2 cones per ITN piece. ITNs that failed to achieve WHO efficacy criteria in these cone bioassays (pooled knock-down ≥ 95% or pooled 24hrs mortality ≥ 80%) were subjected to tunnel tests. For each ITN that failed in cone bioassays, only one ITN piece (with cone bioassay mortality that is closest to the mean) was tested in tunnels. Approximately 100 unfed 5–8 days old susceptible An gambiae Kisumu were exposed to each ITN piece in the tunnel tests and efficacy of alpha-cypermethrin in Interceptor® and Royal Guard® was measured in terms of mortality after 24hrs (≥ 80%) or blood-feeding inhibition (≥ 90%). Bioefficacy of pyriproxyfen in Royal Guard® To monitor the bioefficacy of pyriproxyfen in Royal Guard, blood-fed 5–8 days old mosquitoes of the pyrethroid-resistant An coluzzii Akron strain were exposed for 3 minutes in cone bioassays and assessed for the impact on ovary development using dissection. Dissections were performed 72 hrs after exposure under a microscope and mosquitoes were classified as fertile or infertile following previously described SOPs [ 22 ]. A total of 80–100 blood-fed mosquitoes were tested against each Royal Guard® ITN in replicates of 5 mosquitoes per cone and 4 cones per ITN piece and efficacy was measured for each ITN in terms of the proportional reduction in fertility relative to control unexposed mosquitoes. A cut off of ≥ 50% reduction in fertility relative to the untreated control nets was applied to determine pass rates of Royal Guard® nets for pyriproxyfen bioefficacy. Only tests for which at least 30% of unexposed mosquitoes are found fertile were considered valid. Bioefficacy of chlorfenapyr in Interceptor® G2 The bioefficacy of chlorfenapyr in Interceptor® G2 was assessed in tunnel tests using the pyrethroid-resistant Akron strain. To improve the efficiency of the tunnel test bioassays, only 1 ITN piece per whole Interceptor® G2 ITN was tested in tunnels. For each tunnel, a total of ~ 100 unfed 5–8 days old pyrethroid resistant An coluzzii Akron were exposed overnight and efficacy of Interceptor® G2 in tunnels was measured in terms of mosquito mortality after 72hrs (≥ 80%) or blood-feeding inhibition (≥ 90%). Chemical analysis methods Net pieces preserved for chemical analysis at 0, 12, 24 and 36 months (510 pieces per ITN type) were wrapped in Aluminum foil and stored at 4 0 C (+/-2 0 C) and afterwards shipped to Centre Walloon de Recherches Agronomiques (CRA-W), Belgium, for detection of fabric weight and AI content. The methods used for AI extraction have been described elsewhere [ 14 , 23 ]. Gas Chromatography with Flame Ionisation Detection (GC-FID) was used to determine the content of each AI. ITN pieces from the same net were pooled to provide a single chemical content reading per AI for each whole ITN per net type sampled at each time point. Data management Household data collected during the census and ITN follow-up surveys were captured on electronic forms using smartphones installed with OpenDataKit (ODK) Collect while entomological data was recorded on data entry forms and double-entered pre-designed Excel databases. Throughout the study, electronic data was stored encrypted while paper forms were locked up in secured cabinets and were available only to study investigators and data management staff by passwords and keys. All personal data was anonymized using a unique identifier number for each participant and household to ensure confidentiality. At the end of the study, all electronic files and data entry forms have been respectively stored on the server and archive of the CREC-LSHTM GLP-certified Facility for 10 years. Statistical analysis Data from the surveys at 6, 12, 24, 30 and 36 months was used to calculate attrition, functional survival and median survival time. Attrition was estimated at each time point as the proportion of study nets that were not found in households either due to physical damage, removal or repurposing relative to the number of nets distributed as a baseline after removing nets that were lost to follow-up. Functional survival was calculated at each survey time point as the proportion of nets in serviceable condition after excluding nets that were given away, sold or stolen. Median survival was calculated as the linear extrapolation of the survival values from either the 12- or 24-month rounds (whichever was < 85% survival) and the 36 months round to the y = 50% line, using the following formula: $$\:Tm=t1+\left(t2-t1\right)*(p1-50)/(p1-p2)$$ where tm is the median survival time, t1 and t2 are the first and second timepoints in years and p1 and p2 are the proportions surviving to the first and second timepoints respectively in percent. Confidence intervals (CI) for this estimate were calculated by projecting the 95% CI from the survival estimates in the same way as described above. Hazard ratios (HRs) for the difference in functional survival and 95% confidence intervals were predicted using Cox proportional regression models. A chi-squared test was used to assess the proportion of nets of each ITN type passing the WHO criteria for alphacypermethrin, chlorfenapyr and pyriproxyfen bioefficacy based on combined cone and tunnel tests. Ethical considerations Ethical approval was obtained from the ethics review boards of the Ministry of Health in Benin (N°6/30/MS/DC/DRFMT/CNERS/SA), the institutional review board of the London School of Hygiene and Tropical Medicine (N°16,237), and the WHO Research Ethics Review Committee (ERC.0003153). The cRCT is registered on clinicaltrials.gov (NCT03931473) and the study protocol was published before the start of the trial [ 16 ]. Heads of households selected for the durability study gave informed consent prior to their participation. The consent form was written in French and explained to them in their local language. Where the individual was unable to read or write, their fingerprint was taken, and a signature obtained from a witness to the informed consent procedure. All personal data was anonymised prior to data processing. Approval for use of guinea pigs for tunnel tests was obtained from the LSHTM Animal Welfare Ethics Review Board (Ref: 2020-01). The methods described in this paper were carried out following relevant guidelines and regulations. Results ITN survivorship, attrition rate and fabric integrity ITN survivorship A total of 2,428 ITNs were recruited at baseline consisting of 792 Interceptor, 820 Royal Guard® and 816 Interceptor® G2. Table 2 provides details of the number of nets that were available at each time point and the ITN functional survival rate calculated as the proportion of nets that were found in serviceable condition. Functional survival declined across all ITN types over time and had reduced to < 20% at the 36-month follow-up. The fastest decline in functional survival was observed with Royal Guard® (38% at 24 months and 6% at 36 months). Median ITN survival time was highest with Interceptor® (2.3 years, 95% CI 2.2–2.4 years, p < 0.05, Table 3 ). Royal Guard® also showed a significantly lower median survival time relative to Interceptor® [1.6 years (1.4–1.8 years) vs. 2.3 years (2.2–2.4 years); HR = 1.49, 95% CI = 1.36–1.66, p < 0.001] and to Interceptor® G2 [1.6 years (1.4–1.8 years) vs. 2.1 years (2.0-2.2 years); HR = 1.33, 95% CI = 1.20–1.47, p < 0.001]. Table 2 Functional survivorship of ITNs ITN types Interceptor® Royal Guard® Interceptor® G2 All ITNs ITNs marked at baseline 792 816 820 2428 6 months ITNs available 696 635 698 2029 % Attrition (95% CI) 12.1 (9.7–14.4) 22.2 (19.0-25.1) 14.9 (12.2–17.3) 16.4 (14.8–17.9) ITNs in serviceable condition 680 607 662 1948 ITNs given away 110 178 109 397 % Functional survival (95% CI) 99.7 (98.9–99.9) 94.5 (92.5–96.2) 93.6 (91.6–95.3) 95.3 (94.9–96.7) 12 months ITNs available 587 465 573 1625 % Attrition (95% CI) 25.9 (22.3–28.9) 43.0 (38.5–46.4) 30.1 (26.4–33.3) 33.1 (30.8–34.9) ITNs in serviceable condition 553 428 515 1496 ITNs given away 216 278 201 695 % Functional survival (95% CI) 96 (94.1–97.5) 79.0 (75.3–82.3) 83.7 (80.6–86.6) 86.3 (84.6–87.9) 24 months ITNs available 420 276 359 1055 % Attrition (95% CI) 47.0 (42.2–50.5) 66.2 (60.6–69.4) 56.2 (51.1–59.6) 56.5 (53.6–58.5) ITNs in serviceable condition 370 222 299 891 ITNs given away 216 238 271 725 % Functional survival (95% CI) 64.2 (60.2–68.2) 38.1 (33.2–42.2) 54.9 (50.6–59.1) 52.3 (49.9–54.7) 30 months ITNs available 278 139 236 653 % Attrition (95% CI) 64.9 (59.3–68.2) 83.0 (76.7–85.6) 71.2 (65.4–74.3) 73.1 (69.7–74.9) ITNs in serviceable condition 192 104 161 457 ITNs given away 395 236 433 1064 % Functional survival (95% CI) 48.3 (43.3–53.4) 17.8 (14.8–21.1) 42 (37.0–47.2) 33.5 (31.0–36.1) 36 months ITNs available 154 60 165 165 % Attrition (95% CI) 80.6 (74.3–83.3) 92.6 (86.0-94.4) 79.9 (73.8–82.6) 93.2 (89.4–94.2) ITNs in serviceable condition 135 45 131 131 ITNs given away 495 333 540 540 % Functional survival (95% CI) 19.5 (16.6–22.7) 6.2 (4.6–8.2) 18.4 (15.7–21.5) 14.6 (13.2–16.2) Table 3 Median survival times Median survival time (95% CI) Hazard Ratio (95% CI) P-value Interceptor® 2.3 (2.2–2.4) 1 N/A Royal Guard® 1.6 (1.4–1.8) 1.49 (1.36–1.66) p < 0.001 Interceptor® G2 2.1 (2.0-2.3) 1.13 (1.02–1.26 p = 0.027 All ITNs 2.1 (2.0-2.1) N/A N/A ITN fabric integrity and proportionate hole index of study nets Figure 2 shows the proportionate hole index of nets that were found and assessed for fabric integrity at each time point. The proportion of nets that were found in good and acceptable condition relative to the numbers distributed at baseline had declined substantially over time and was < 40% at 24 months post-distribution. At 36 months, less than 20% were found in good or acceptable conditions relative to the numbers distributed at baseline. Reasons for ITN attrition The most common reason for ITN attrition in the first 24 months of the study was that the nets had been used elsewhere or given away to relatives (Fig. 3 ). The proportion of ITNs that were discarded due to physical damage was < 10% at 6 months and increased to 25–45% at 24 months. By the 36-month survey, ~ 80% of ITNs had been discarded due to physical damage. Non-study nets in use and ITN preference survey Approximately 50–80% of study nets that were found and assessed at each timepoint were hanging over sleeping places indicating active use of the nets (Fig. 4 ). For Interceptor® G2, this proportion was > 70% at all time points. With Interceptor, the proportion hanging was relatively lower (at 6 and 12 months (50–60%) but increased substantially at later time points. Royal Guard® generally showed low hanging rates of 50–60% across all time points indicating a lower use rate. Table 4 shows the number of non-study nets that were found hanging in households in each study arm that were surveyed at 24 months post-distribution to investigate the replacement of study nets with other ITN types. A total of 761 non-study nets were found in 362 surveyed houses and 75% of these nets were PermaNet® 2.0 nets that had been distributed in the previous ITN mass campaign. The highest proportion of non-study nets in use was found in households in the Royal Guard® arm (52%) indicating a higher replacement of Royal Guard® nets relative to Interceptor® G2 (14.3%) and Interceptor® (33.5%) nets. Of a total of 300 heads of households surveyed for ITN fabric texture preference, 96% indicated a preference for polyester net fabric over polyethylene net fabric. The polyester fabric texture was perceived to be softer, cooler and less abrasive on the skin compared to the polyethylene fabric texture. About 60% of householders believed that the polyethylene nets shrunk in size after washing compared to 4% for polyester nets. Table 4 Proportion of non-study nets in use per study arm Royal Guard Interceptor G2 Interceptor TOTAL N HH surveyed 138 110 114 362 N non-study nets in use 397 109 255 761 % non-study nets in use 52.2 14.3 33.5 100 Bioefficacy in laboratory bioassays Susceptibility of test strains Figure 5 presents annual results obtained in susceptibility bioassays performed with mosquito strains (Kisumu and Akron) tested against the study nets in the laboratory bioassays. For the Akron strain, during each year of the study, mortality in alpha-cypermethrin-treated tube tests remained 90% showing that the strain maintained its resistance to pyrethroids and susceptibility to chlorfenapyr. The reduction in fertility of Akron mosquitoes exposed to pyriproxyfen in bottle bioassays was also > 90% during each year of testing showing susceptibility to the insecticide throughout the study. Mortality in further bioassays performed with 5X and 10X the diagnostic dose of alpha-cypermethrin was < 95% at all timepoints showing that Akron strain had a high intensity of pyrethroid resistance throughout the study. Susceptibility bioassays performed with the Kisumu strain also showed that the strain remained susceptible to all three insecticides through the course of the study. Bioefficacy results with Interceptor® A total of 7,627 susceptible An gambiae Kisumu mosquitoes were exposed to Interceptor® nets in 3 min cone bioassays at baseline and at 12, 24 and 36 months after household use. Overall mosquito mortality declined from 76.8% at baseline to 58.3% at 24 months and 44.4% at 36 months (Table 5 ). About half of the nets tested in cone bioassays failed to achieve WHO criteria in cone bioassays and were thus tested in tunnel tests. Mosquito mortality in tunnel tests was 98–100% up to 12 months but declined to 53.7% at 24 months before rising to 87.4% at 36 months. Overall blood-feeding inhibition in tunnels generally exceeded 90% except at 24 months when it was 79.7%. Mortality with control untreated ITN pieces did not exceed 5% at any time point. Blood-feeding inhibition in tunnel tests was > 75% at each time point. All 30 Interceptor® ITNs passed efficacy criteria in either cone bioassays or tunnel tests at baseline and 12 months though the numbers passing reduced to 19 at 24 months and later increased to 27 at 36 months. Table 5 Results with Interceptor® nets tested against the susceptible Kisumu strain in cone bioassays and tunnel tests at baseline, 12, 24 and 36 months post-distribution. Only nets that failed WHO criteria in cone bioassays were tested in tunnels. Values along a row bearing the same letter superscript are not significantly different (p > 0.05, t-test) Treatments Baseline 12 months 24 months 36 months N ITNs Tested 30 30 30 30 Cone bioassay results N pieces tested 150 120 120 120 N exposed 1530 1233 2326 2538 N KD 1394 1187 1961 1963 N dead 1175 934 1355 1126 % KD (95% CI) 91.1 (86.3–92.5) 96.3 (90.8–97.4) 84.3 (80.6–85.8) 77.3 (73.9–78.9) % Dead (95% CI) 76.8 (72.4–78.9) 75.8 (70.9–78.2) 58.3 (55.2–60.3) 44.4 (41.8–46.3) Tunnel test results with failed nets from cone bioassays N pieces tested 14 6 15 16 N exposed 1589 543 1519 1602 N dead 1564 543 815 1400 N blood-fed 95 1 240 102 % dead (95% CI) 98.4 (93.5–99.0) 100 (96–100) 53.7 (50.0-56.2) 87.4 (82.8–89.0) % Blood-fed 6 (4.8–7.2) 0.2 (0-0.6) 15.8 (13.8–17.6) 6.4 (5.2–7.6) % BFI 92.3 99.7 79.7 91.8 N ITN passing 30/30 30/30 19/30 27/30 Bioefficacy results with Royal Guard® Results obtained in bioassays investigating the bioefficacy of Royal Guard® are presented in Table 6 . To assess the bioefficacy of alpha-cypermethrin in Royal Guard, a total of 8,363 susceptible An gambiae Kisumu mosquitoes were exposed to Royal Guard® nets in 3-minute cone bioassays at baseline and at 12, 24 and 36 months post-distribution. Overall mosquito mortality was > 90% at all time points of testing. All ITNs passed WHO criteria for alpha-cypermethrin efficiency in cone bioassays hence tunnel tests were not performed. A total of 1,966 blood-fed pyrethroid-resistant An coluzzii Akron mosquitoes that survived exposure to Royal Guard® nets in 3 min cone bioassays at baseline and 12, 24 and 36 months were dissected to investigate the bioefficacy of pyriproxyfen. The overall reduction in fertility rate was 99.3% at baseline but declined substantially < 40% at 12 and 24 months and was 24.3% at 36 months. At each time point, mortality with control untreated net pieces did not exceed 5% at each time point and fertility rates with control unexposed mosquitoes were > 50%. All 30 Royal Guard® ITNs passed the criteria for alpha-cypermethrin bioefficacy at all time points. For pyriproxyfen bioefficacy, the number of Royal Guard® ITNs that passed efficacy criteria (> 50% reduction in fertility relative to control) was 30 at baseline and decreased substantially from 13 at 12 months to only 4 at 36 months. Table 6 Results with Royal Guard® nets tested in cone bioassays against susceptible Kisumu and blood-fed pyrethroid-resistant Akron strains at baseline, 12, 24 and 36 months post-distribution. Values along a row bearing the same letter superscript are not significantly different (p > 0.05, t-test) Treatments Baseline 12 months 24 months 36 months N ITNs Tested 30 30 30 30 Cone bioassays with Kisumu to investigate alpha-cypermethrin bioefficacy N pieces tested 150 120 120 120 N exposed 1491 2351 2326 2468 N KD 1491 2345 2324 2434 N dead 1491 2315 2182 2378 % KD (95% CI) 100.0 (96–100) 99.7 (95.7–99.9) 99.9 (95.8–100) 98.6 (94.7–99.1) % Dead (95% CI) 100 (96–100) 98.5 (94.5–99.0) 93.8 (89.9–100) 96.4 (92.5–97.1) N ITNs passing 30/30 30/30 30/30 30/30 Cone bioassays with blood-fed Akron to investigate pyriproxyfen bioefficacy N pieces tested 150 120 120 120 N exposed 2803 1152 2438 2480 N dissected 143 217 873 950 N fertile 1 138 551 707 N Unfertile 142 79 322 243 % Fertile (95% CI) 0.7 (0.4-1.0) 63.6 (59.0-66.4) 63 (59.9–64.9) 74.4 (71.0-76.1) % Reduction in fertility relative to control 99.3 35.3 36.0 24.3 N ITNs passing 30/30 13/30 11/30 4/30 Bioefficacy results with Interceptor® G2 A total of 13,092 pyrethroid-resistant An coluzzii Akron mosquitoes were exposed to Interceptor® G2 nets in tunnel tests through the course of the study. Overall mosquito mortality was 95.7% at baseline and declined < 80% at subsequent time points (Table 7 ). Blood-feeding inhibition did not exceed 90% at any time point and had declined to 50%. All 30 Interceptor® G2 nets passed the criteria for chlorfenapyr bioefficacy in tunnel tests at baseline though this number reduced to 19 at 12 months and was 6 and 8 at 24 and 36 months respectively. Table 7 Results with Interceptor® G2 nets tested in tunnel tests against the pyrethroid-resistant Akron strain at baseline, 12, 24 and 36 months post-distribution. Treatments Baseline 12 months 24 months 36 months N ITNs Tested 30 30 30 30 N pieces tested 30 30 30 30 N exposed 3258 3308 3308 3218 N dead 3118 2715 1711 1938 N blood-fed 686 1028 1831 1512 % dead (95% CI) 95.7 (92.6–96.7) 82.1 (79.0-83.4) 51.7 (49.3–53.4) 60.2 (49.22–53.4) % Blood-fed 21.1 (19.5–22.5) 31.1(29.2–32.7) 55.4 (52.8–57.1) 47 (44.6–48.7) % BFI 73.7 61.2 31.0 41.5 N ITNs passing 30/30 19/30 6/30 8/30 Proportion of ITNs passing WHO criteria The percentages of ITNs of each type that passed efficacy criteria for each active ingredient at each time point are presented in Fig. 6 . ITN pass rate for bioefficacy of alpha-cypermethrin in Interceptor® was 100% at baseline and at 12 months though it declined to 65% at 24 months and later increased to 90% at 36 months. Royal Guard® showed 100% ITN pass rate for the bioefficacy of alpha-cypermethrin throughout the study meanwhile less than 40% of Royal Guard® and Interceptor® G2 ITNs withdrawn at 24 months passed efficacy criteria for pyriproxyfen and chlorfenapyr respectively. The proportion of ITNs passing bioefficacy criteria for pyriproxyfen in Royal Guard® and chlorfenapyr in Interceptor® G2 were generally similar at each time point (p > 0.05). The results therefore showed a faster decline in bioefficacy of the non-pyrethroid insecticide compared to alpha-cypermethrin. Changes in chemical content over time The mean active ingredient content was within target expectations for each ITN type at baseline (Table 8). For both dual active ingredient nets, greater amounts of alpha-cypermethrin were retained compared to the non-pyrethroid (Fig. 7 ). Over 50% of alpha-cypemethrin was still available in Royal Guard® nets at 36 months while the content of pyriproxyfen had reduced to 26% of the target. A similar trend was observed with Interceptor® G2 though the nets had lost > 85% of their chlorfenapyr content at 36 months. Table 8 Chemical content (g/kg) of insecticide-treated nets withdrawn at 12-, 24- and 36-months post-distribution. Discussion This study evaluated the attrition, fabric integrity and insecticidal durability of two dual AI ITNs (Interceptor® G2 and Royal Guard®) compared to a WHO-prequalified alpha-cypermethrin net (Interceptor®) as part of cRCT performed in the Zou department of Benin between 2020 to 2023. ITN durability studies are essential for planning their replacement and for making programmatic and procurement decisions. In terms of ITN survivorship, the overall proportion of study nets available in households had reduced to 52% after 24 months and only 15% of nets were still available after 36 months. Overall ITN median survival time was 2.0 years which falls substantially below the 3-year durability assumed by the Benin NMCP’s policy of triannual ITN campaign cycles. ITN attrition due to physical damage was generally low during the first 2 years (< 25%) but increased substantially at the end point of the study (~ 80%) indicating a significant loss in physical integrity of the study nets after 24 months of operational age. These findings align with the statistical inference study that reported poor ITN retention rates of < 2 years in most communities in Africa [ 4 ]. Nevertheless, an ITN coverage survey performed as part of the cRCT at 24 months showed that the study nets were mostly replaced by extra nets that householders still had in their possession from previous campaigns thus maintaining an overall high ITN coverage of > 90% in the study area [ 9 ]. This finding highlights the need for strategies to optimise ITN quantification and allocation to ensure equitable access across target populations [ 3 ]. Comparing ITN survivorship between ITN types, the study demonstrated a higher median survival time for Interceptor® (2.3 years) and Interceptor® G2 (2.1 years) compared to Royal Guard® (1.6 years). This was further supported by the lower proportion of Royal Guard® nets hanging over sleeping places compared to Interceptor® and Interceptor® G2 and their increased replacement with other non-study nets. These findings can be attributed to differences in fabric type between the study nets; Interceptor® and Interceptor® G2 are made of polyester fabric while Royal Guard® is made of polyethylene fabric. Indeed, the qualitative survey performed 24 months post-distribution showed that householders overwhelmingly preferred ITNs made of polyester fabric due to their softer texture compared to ITNs made from polyethylene fabric which may have driven the higher replacement of Royal Guard® nets mostly with spare polyester nets (mainly PermaNet® 2.0) from the previous ITN campaigns. This may have contributed to the lack of an improved epidemiological impact with Royal Guard® relative to Interceptor® in the cRCT [ 9 ]. ITN users’ low preference for the polyethylene ITN fabric texture has been demonstrated in multiple studies in Africa [ 24 ]. While an earlier study evaluating the durability of a polyethylene net (Olyset® Plus) distributed in Benin in 2010 reported a median survival time of just 2 years [ 25 ], more recent durability studies with polyester ITNs in Benin have shown longer median survival times of 2.8 years [ 26 ]. Although it has been argued that householders tend to use the net types that are available to them and that ITN use at the population level may not be affected by the user’s fabric texture preference [ 27 ], the findings from our study indicate that householders in Benin would be inclined to discard polyethylene nets more quickly compared to polyester nets. This finding supports the Benin NMCP’s policy of excluding polyethylene nets from their mass ITN campaigns. Given that the polyethylene fabric texture is more suitable for the application of some non-pyrethroid compounds on ITNs, strategies to improve the softness of polyethylene texture used for ITNs may help improve their acceptability and use by householders. The laboratory bioassays showed better retention of the bioefficacy of the pyrethroid component in the dual AI ITNs over 3 years of operational use compared to the non-pyrethroid component. The proportion of ITNs passing predetermined efficacy criteria in bioassays had reduced to < 40% at 24 months of operational age for pyriproxyfen in Royal Guard® and chlorfenapyr in Interceptor® G2 while 100% of Royal Guard® nets passed efficacy criteria for the pyrethroid component throughout the study. This can be explained by the higher loss rate of the non-pyrethroid active ingredients from the dual AI nets relative to the pyrethroid AI. Studies have also shown a significantly higher loss of PBO (> 80%) compared to pyrethroids on pyrethroid-PBO ITNs as they age under operational conditions [ 28 , 29 , 30 ]. This suggests that pyrethroids are generally more durable on ITNs than non-pyrethroid compounds used on existing dual AI nets. This further highlights the need for more innovative technologies to improve the insecticidal durability of non-pyrethroid AIs on mosquito nets. As new non-pyrethroid AIs are applied to ITNs, the methods and strains used for monitoring their bioefficacy under operational conditions must align with their mode of action. In this study, we modified existing WHO bioassays to allow assessment of the delayed toxic effects of chlorfenapyr on Interceptor® G2 using tunnel tests and the sterilising effects of pyriproxyfen on Royal Guard® by dissecting the ovaries of exposed blood-fed females. The bioassays provided interpretable results that aligned with changes in the content of the non-pyrethroid AIs over time. Bioassays that did not meet predefined validity criteria i.e cut-offs for mortality, blood-feeding or fertility in control unexposed mosquitoes were very rare. The susceptibility data also showed that the pyrethroid-resistant An coluzzii Akron strain that was used for bioefficacy testing of the non-pyrethroids maintained its resistance status throughout the study. This suggests that the methods used for monitoring the bioefficacy of both non-pyrethroid AIs over time were appropriate and could therefore contribute to the development of new WHO guidelines for investigating the bioefficacy of WHO-prequalified dual AI ITNs under long-term community use. While the laboratory bioassays demonstrate how the bioefficacy of each ITN type changed over time, they do not provide a direct comparison between the ITN types given that different methods and mosquito strains had to be used to monitor changes in bioefficacy of each AI over time. Experimental hut trials were thus performed in parallel against wild free-flying pyrethroid-resistant malaria vectors in the Cove hut station with study nets withdrawn from households at 12, 24 and 36 months of operational age (unpublished data). The hut trial results have shown the superiority of Interceptor® G2 nets over other dual AI ITN types though the improved impact relative to Interceptor® had declined significantly with 24- and 36-months nets. This is supported by the substantial reduction in the proportion of Interceptor® G2 nets passing criteria for chlorfenapyr bioefficacy in the laboratory bioassays after 24 months in the present study relative to Interceptor® nets (< 30% vs 63–90%). The reduced bioefficacy and chemical content of chlorfenapyr in Interceptor® G2 may therefore partly explain the loss of its improved epidemiological impact relative to Interceptor® in the third year of the cRCT [ 31 ]. Given the dependence of most malaria-endemic countries on triannual ITN campaigns for malaria prevention and control, innovative strategies and cost-effective interventions that can be deployed to improve vector control in the third-year post-ITN distribution are needed. Conclusion This study demonstrated a median ITN survival time of 2.1 years for Interceptor® G2 and 1.6 years for Royal Guard® in communities in Benin. Royal Guard® nets were less used and discarded more quickly by householders partly due to their low preference for polyethylene nets relative to polyester nets. The insecticidal efficacy and content of the pyrethroid AI was more durable relative to the non-pyrethroid AIs in Interceptor® G2 and Royal Guard®. With Royal Guard®, all nets passed the bioefficacy criteria for the pyrethroid component at 36 months while only 14% passed the bioefficacy criteria for pyriproxyfen. With Interceptor® G2, only 25% of nets passed the bioefficacy criteria for chlorfenapyr at 36 months. The content of the non-pyrethroid insecticides at 36 months had reduced by 85% for chlorfenapyr in Interceptor® G2 and 73% for pyriproxyfen in Royal Guard® as opposed to 65% and 47% for the alphacypermethrin content respectively. The results corroborate the findings from the cRCT. Abbreviations PBO Piperonyl butoxide ITN Insecticide-treated nets LLIN Long-lasting insecticidal nets WHO World Health Organization PQ Prequalification team AI Active ingredient GLP Good Laboratory Practice cRCT Cluster randomised controlled trial SSA Sub Saharan Africa NMCP National Malaria Control Programme CREC Centre de Recherche Entomologique de Cotonou LSHTM London School of Hygiene & Tropical Medicine PAMVERC Pan African Malaria Vector Research Consortium Declarations Ethical approval and consent to participate Ethical approval was obtained from the ethics review boards of the Ministry of Health in Benin (N°6/30/MS/DC/DRFMT/CNERS/SA), the institutional review board of the London School of Hygiene and Tropical Medicine (N°16,237), and the WHO Research Ethics Review Committee (ERC.0003153). The cRCT is registered on clinicaltrials.gov (NCT03931473) and the study protocol was published before the start of the trial [16]. Heads of households selected for the durability study gave informed consent prior to their participation. The consent form was written in French and explained to them in their local language. Where the individual was unable to read or write, their fingerprint was taken, and a signature obtained from a witness to the informed consent procedure. All personal data was anonymised prior to data processing. Approval for use of guinea pigs for tunnel tests was obtained from the LSHTM Animal Welfare Ethics Review Board (Ref: 2020-01). The methods described in this paper were carried out following relevant guidelines and regulations. Consent for publication Not applicable Competing interests The authors declare that they have no competing interests. Funding This study was supported by a grant to the London School of Hygiene and Tropical Medicine from Unitaid and The Global Fund through the Innovative Vector Control Consortium (IVCC). The third year of the trial was funded by the Net Transition Initiative of the Global Fund. The funders have no role in the study design, data collection and analysis and decision to publish this manuscript. Authors’ contributions C.N. designed the methods, was responsible for the overall conduct of the study and drafted the manuscript. A.F, and J.A. performed the field surveys with support from A.S. while E.D. supported data management. J.F. performed the laboratory bioassays supported by T.S. and R.G.. D.T. ensured the availability of test mosquitoes and performed the susceptibility bioassays. M.B. and O.P. performed the chemical analysis. C.N., A.F., J.F. and I.A. analysed the data and prepared the figures and tables. C.N., M.A., N.P., J.C., G.P. and M.C.A. were responsible for the management of the cluster randomized controlled trial and contributed to manuscript revision. All authors reviewed the manuscript. Acknowledgements We thank Christen Fornadel of IVCC and Kate Kolaczinski of The Global Fund for project coordination. We also thank BASF and DCT for supplying the study nets and the community leaders and members of the Cove, Zagnanado and Ouinhi districts of the Zou region for their support and collaboration. We appreciate the National Malaria Control Programme of Benin for distributing the study nets and for their continuous support through the trial. References Bhatt S, Weiss D, Cameron E, Bisanzio D, Mappin B, Dalrymple U, et al. The effect of malaria control on Plasmodium falciparum in Africa between 2000 and 2015. Nature. 2015;526 7572:207–11. WHO. World Malaria report. World Health Organisation, Geneva. 2023. Koenker H, Yukich J, Erskine M, Opoku R, Sternberg E, Kilian A. How many mosquito nets are needed to maintain universal coverage: an update. Malaria Journal. 2023;22 1:200; doi: 10.1186/s12936-023-04609-z . https://doi.org/10.1186/s12936-023-04609-z. Bertozzi-Villa A, Bever CA, Koenker H, Weiss DJ, Vargas-Ruiz C, Nandi AK, et al. Maps and metrics of insecticide-treated net access, use, and nets-per-capita in Africa from 2000–2020. Nat Commun. 2021;12 1:3589; doi: 10.1038/s41467-021-23707-7 . Kilian A, Obi E, Mansiangi P, Abílio AP, Haji KA, Blaufuss S, et al. Variation of physical durability between LLIN products and net use environments: summary of findings from four African countries. Malaria Journal. 2021;20 1:26; doi: 10.1186/s12936-020-03549-2 . https://doi.org/10.1186/s12936-020-03549-2. WHO. Guidelines for monitoring the durability of long-lasting insecticidal mosquito nets under operational conditions. Geneva, Switzerland: World Health Organization. 2011. WHO. Guidelines for malaria vector control. Geneva, Switzerland: World Health Organization. 2024. Mosha JF, Kulkarni MA, Lukole E, Matowo NS, Pitt C, Messenger LA, et al. Effectiveness and cost-effectiveness against malaria of three types of dual-active-ingredient long-lasting insecticidal nets (LLINs) compared with pyrethroid-only LLINs in Tanzania: a four-arm, cluster-randomised trial. Lancet. 2022;399 10331:1227–41; doi: 10.1016/S0140-6736(21)02499-5 . https://www.ncbi.nlm.nih.gov/pubmed/35339225 . Accrombessi M, Cook J, Dangbenon E, Yovogan B, Akpovi H, Sovi A, et al. Efficacy of pyriproxyfen-pyrethroid long-lasting insecticidal nets (LLINs) and chlorfenapyr-pyrethroid LLINs compared with pyrethroid-only LLINs for malaria control in Benin: a cluster-randomised, superiority trial. Lancet. 2023;401 10375:435–46; doi: 10.1016/s0140-6736(22)02319-4 . AMP. Alliance for malaria prevention; mass campagn tracker. https://allianceformalariapreventioncom/mass-campaign-tracker/?_sfm_mc_date_of_import=20221015 . 2023;Accessed 28th October 2023. Organization WH: Determination of fabric strength of long-lasting insecticidal nets: report of a WHO consultation, Geneva, 20–22 August 2014. World Health Organization; 2015. WHO. Guidelines for laboratory and field testing of long-lasting insecticidal nets. Geneva, Switzerland: World Health Organization. 2013. Oxborough RM, N'Guessan R, Jones R, Kitau J, Ngufor C, Malone D, et al. The activity of the pyrrole insecticide chlorfenapyr in mosquito bioassay: towards a more rational testing and screening of non-neurotoxic insecticides for malaria vector control. Malar J. 2015;14:124; doi: 10.1186/s12936-015-0639-x . https://www.ncbi.nlm.nih.gov/pubmed/25879231 . Ngufor C, Agbevo A, Fagbohoun J, Fongnikin A, Rowland M. Efficacy of Royal Guard, a new alpha-cypermethrin and pyriproxyfen treated mosquito net, against pyrethroid-resistant malaria vectors. Scientific Reports. 2020;10 1:12227; doi: 10.1038/s41598-020-69109-5 . https://doi.org/10.1038/s41598-020-69109-5. Ngufor C, N'Guessan R, Fagbohoun J, Todjinou D, Odjo A, Malone D, et al. Efficacy of the Olyset Duo net against insecticide-resistant mosquito vectors of malaria. Sci Transl Med. 2016;8 356:356ra121; doi: 10.1126/scitranslmed.aad3270 . https://www.ncbi.nlm.nih.gov/pubmed/27629488 . Accrombessi M, Cook J, Ngufor C, Sovi A, Dangbenon E, Yovogan B, et al. Assessing the efficacy of two dual-active ingredients long-lasting insecticidal nets for the control of malaria transmitted by pyrethroid-resistant vectors in Benin: study protocol for a three-arm, single-blinded, parallel, cluster-randomized controlled trial. BMC Infect Dis. 2021;21 1:194; doi: 10.1186/s12879-021-05879-1 . https://www.ncbi.nlm.nih.gov/pubmed/33607958 . Ngufor C, Fongnikin A, Fagbohoun J, Agbevo A, Syme T, Ahoga J, et al. Evaluating the attrition, fabric integrity and insecticidal durability of two dual active ingredient nets (Interceptor® G2 and Royal® Guard): methodology for a prospective study embedded in a cluster randomized controlled trial in Benin. Malaria Journal. 2023;22 1:276; doi: 10.1186/s12936-023-04708-x . https://doi.org/10.1186/s12936-023-04708-x. Accrombessi M, Akogbeto MC, Dangbenon E, Akpovi H, Sovi A, Yovogan B, et al. Malaria Burden and Associated Risk Factors in an Area of Pyrethroid-Resistant Vectors in Southern Benin. Am J Trop Med Hyg. 2022;107 3:681–8; doi: 10.4269/ajtmh.22-0190 . Yovogan B, Sovi A, Padonou GG, Adoha CJ, Akinro B, Chitou S, et al. Pre-intervention characteristics of the mosquito species in Benin in preparation for a randomized controlled trial assessing the efficacy of dual active-ingredient long-lasting insecticidal nets for controlling insecticide-resistant malaria vectors. PLoS One. 2021;16 5:e0251742; doi: 10.1371/journal.pone.0251742 . https://www.ncbi.nlm.nih.gov/pubmed/34014982 . Mutunga JM, Anderson TD, Craft DT, Gross AD, Swale DR, Tong F, et al. Carbamate and pyrethroid resistance in the akron strain of Anopheles gambiae. Pestic Biochem Physiol. 2015;121:116–21; doi: 10.1016/j.pestbp.2015.03.001 . Myers A, Fagbohoun J, Houetohossou G, Ndombidje B, Govoetchan R, Todjinou D, et al. Identifying suitable methods for evaluating the sterilizing effects of pyriproxyfen on adult malaria vectors: a comparison of the oviposition and ovary dissection methods. Malaria Journal. 2024;23 1:164; doi: 10.1186/s12936-024-04983-2 . https://doi.org/10.1186/s12936-024-04983-2. CHRISTOPHERS SR. The development of the egg follicle in anophelines. Paludism. 1911;2:73–88. Syme T, N’dombidjé B, Gbegbo M, Todjinou D, Ariori V, De Vos P, et al. PermaNet Dual, a new deltamethrin-chlorfenapyr mixture net, shows improved efficacy against pyrethroid-resistant Anopheles gambiae sensu lato in southern Benin. Scientific Reports. 2023;13 1:12232; doi: 10.1038/s41598-023-39140-3 . https://doi.org/10.1038/s41598-023-39140-3. Kim S, Piccinini D, Mensah E, Lynch M. Using a Human-Centered Design Approach to Determine Consumer Preferences for Long-Lasting Insecticidal Nets in Ghana. Glob Health Sci Pract. 2019;7 2:160–70; doi: 10.9745/ghsp-d-18-00284 . Gnanguenon V, Azondekon R, Oke-Agbo F, Beach R, Akogbeto M. Durability assessment results suggest a serviceable life of two, rather than three, years for the current long-lasting insecticidal (mosquito) net (LLIN) intervention in Benin. BMC Infectious Diseases. 2014;14 1:69; doi: 10.1186/1471-2334-14-69 . https://doi.org/10.1186/1471-2334-14-69. Ahogni I, Aïkpon R, Ossè R, Dagnon J, Govoetchan R, Attolou R, et al. Field durability of Yorkool® LN nets in the Benin Republic. Advances in Entomology. 2019;8 01:72–92. Koenker H, Yukich JO. Effect of user preferences on ITN use: a review of literature and data. Malaria Journal. 2017;16 1:233; doi: 10.1186/s12936-017-1879-8 . https://doi.org/10.1186/s12936-017-1879-8. Lukole E, Cook J, Mosha JF, Messenger LA, Rowland M, Kleinschmidt I, et al. Protective efficacy of holed and aging PBO-pyrethroid synergist-treated nets on malaria infection prevalence in north-western Tanzania. PLOS Glob Public Health. 2022;2 10:e0000453; doi: 10.1371/journal.pgph.0000453 . Gichuki PM, Kamau L, Njagi K, Karoki S, Muigai N, Matoke-Muhia D, et al. Bioefficacy and durability of Olyset(®) Plus, a permethrin and piperonyl butoxide-treated insecticidal net in a 3-year long trial in Kenya. Infect Dis Poverty. 2021;10 1:135; doi: 10.1186/s40249-021-00916-2 . Raharinjatovo J, Dabiré RK, Esch K, Soma DD, Hien A, Camara T, et al. Physical and insecticidal durability of Interceptor(®), Interceptor(®) G2, and PermaNet(®) 3.0 insecticide-treated nets in Burkina Faso: results of durability monitoring in three sites from 2019 to 2022. Malar J. 2024;23 1:173; doi: 10.1186/s12936-024-04989-w . Accrombessi M, Cook J, Dangbenon E, Sovi A, Yovogan B, Assongba L, et al. Effectiveness of pyriproxyfen-pyrethroid and chlorfenapyr-pyrethroid long-lasting insecticidal nets (LLINs) compared with pyrethroid-only LLINs for malaria control in the third year post-distribution: a secondary analysis of a cluster-randomised controlled trial in Benin. Lancet Infect Dis. 2024; doi: 10.1016/S1473-3099(24)00002-1 . https://www.ncbi.nlm.nih.gov/pubmed/38401551 . Additional Declarations No competing interests reported. Supplementary Files Supplementaryinformation.docx Cite Share Download PDF Status: Published Journal Publication published 07 Oct, 2024 Read the published version in Parasites & Vectors → Version 1 posted Editorial decision: Revision requested 28 Aug, 2024 Reviews received at journal 21 Aug, 2024 Reviews received at journal 20 Aug, 2024 Reviewers agreed at journal 04 Aug, 2024 Reviewers agreed at journal 01 Aug, 2024 Reviewers agreed at journal 31 Jul, 2024 Reviewers agreed at journal 31 Jul, 2024 Reviewers agreed at journal 31 Jul, 2024 Reviewers agreed at journal 30 Jul, 2024 Reviewers agreed at journal 30 Jul, 2024 Reviewers invited by journal 30 Jul, 2024 Editor assigned by journal 24 Jul, 2024 Submission checks completed at journal 24 Jul, 2024 First submitted to journal 22 Jul, 2024 You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. 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Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-4782261","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":335850118,"identity":"98e99a28-1499-4100-b93c-c19134192ec6","order_by":0,"name":"Corine Ngufor","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAABBklEQVRIiWNgGAWjYJCCAxCK8QEDQ4UFgwFMWIKwFmag4jMSDAZsRGhhgGthbCNCC39778PDBRUMefIRyYyPK+dJ2JvLdycw/KhhSJzZgF2LxJnjBodnnGEoNryRzGx4dptE4s423g2MPccYEmfjsMVAIo3hMG8bQ+LGGfnHJBu3SSQYHOPdwMDbwJA4D6+WfyAtyWySjXMk7EFaGP8S1AJUMF8CpKVBgnEDUAszSASXwyTOHGM4zHNMInEDz2NmwwYQ41juhsMyxySMcXmfv72N+TNPjU3i/PZkxocNNTb2BofPbnz4psZGdsYBHNZALWMwQFZwgKiIlMfhjFEwCkbBKBgFDAB3cFdDGKjDYgAAAABJRU5ErkJggg==","orcid":"","institution":"London School of Hygiene and Tropical Medicine (LSHTM)","correspondingAuthor":true,"prefix":"","firstName":"Corine","middleName":"","lastName":"Ngufor","suffix":""},{"id":335850119,"identity":"2beac034-dc4b-43b7-a4af-761ef2cdd063","order_by":1,"name":"Josias Fagbohoun","email":"","orcid":"","institution":"Centre de Recherches Entomologiques de Cotonou (CREC)","correspondingAuthor":false,"prefix":"","firstName":"Josias","middleName":"","lastName":"Fagbohoun","suffix":""},{"id":335850120,"identity":"bb9d55ee-41d1-4229-b4f1-198b6f443915","order_by":2,"name":"Augustin Fongnikin","email":"","orcid":"","institution":"Centre de Recherches Entomologiques de Cotonou (CREC)","correspondingAuthor":false,"prefix":"","firstName":"Augustin","middleName":"","lastName":"Fongnikin","suffix":""},{"id":335850121,"identity":"78e1b015-e476-45c0-9c79-05b3a9026d99","order_by":3,"name":"Juniace Ahoga","email":"","orcid":"","institution":"Centre de Recherches Entomologiques de Cotonou (CREC)","correspondingAuthor":false,"prefix":"","firstName":"Juniace","middleName":"","lastName":"Ahoga","suffix":""},{"id":335850122,"identity":"87d852aa-25a8-4aa6-814d-44b6e2496cff","order_by":4,"name":"Thomas Syme","email":"","orcid":"","institution":"London School of Hygiene and Tropical Medicine (LSHTM)","correspondingAuthor":false,"prefix":"","firstName":"Thomas","middleName":"","lastName":"Syme","suffix":""},{"id":335850123,"identity":"94a8313d-22d3-441f-981e-c69f20e54dbf","order_by":5,"name":"Idelphonse Ahogni","email":"","orcid":"","institution":"Centre de Recherches Entomologiques de Cotonou (CREC)","correspondingAuthor":false,"prefix":"","firstName":"Idelphonse","middleName":"","lastName":"Ahogni","suffix":""},{"id":335850125,"identity":"540b935c-5964-45d2-9645-8e2a58d9408a","order_by":6,"name":"Manfred Accrombessi","email":"","orcid":"","institution":"London School of Hygiene and Tropical Medicine (LSHTM)","correspondingAuthor":false,"prefix":"","firstName":"Manfred","middleName":"","lastName":"Accrombessi","suffix":""},{"id":335850126,"identity":"e594455b-19ef-43d8-aa33-faf908c29829","order_by":7,"name":"Natacha Protopopoff","email":"","orcid":"","institution":"London School of Hygiene and Tropical Medicine (LSHTM)","correspondingAuthor":false,"prefix":"","firstName":"Natacha","middleName":"","lastName":"Protopopoff","suffix":""},{"id":335850127,"identity":"d42700fb-faff-4bb2-a6ac-5e9605b14ff8","order_by":8,"name":"Jackie Cook","email":"","orcid":"","institution":"London School of Hygiene and Tropical Medicine (LSHTM)","correspondingAuthor":false,"prefix":"","firstName":"Jackie","middleName":"","lastName":"Cook","suffix":""},{"id":335850128,"identity":"86d7c9f3-5444-4019-9b51-246cbf0dcfc9","order_by":9,"name":"Edouard Dangbenon","email":"","orcid":"","institution":"Centre de Recherches Entomologiques de Cotonou (CREC)","correspondingAuthor":false,"prefix":"","firstName":"Edouard","middleName":"","lastName":"Dangbenon","suffix":""},{"id":335850132,"identity":"234fb0d3-9fae-4240-933a-0d659eab0b73","order_by":10,"name":"Arthur Sovi","email":"","orcid":"","institution":"London School of Hygiene and Tropical Medicine (LSHTM)","correspondingAuthor":false,"prefix":"","firstName":"Arthur","middleName":"","lastName":"Sovi","suffix":""},{"id":335850135,"identity":"bcaca2b6-cb28-4a5c-8a38-f70fb8e2ae84","order_by":11,"name":"Marie Baes","email":"","orcid":"","institution":"Centre Wallon de Recherches Agronomiques (CRA-W)","correspondingAuthor":false,"prefix":"","firstName":"Marie","middleName":"","lastName":"Baes","suffix":""},{"id":335850137,"identity":"68ce11b6-2c91-46e9-8a53-2b9b743360ff","order_by":12,"name":"Olivier Pigeon","email":"","orcid":"","institution":"Centre Wallon de Recherches Agronomiques (CRA-W)","correspondingAuthor":false,"prefix":"","firstName":"Olivier","middleName":"","lastName":"Pigeon","suffix":""},{"id":335850140,"identity":"aeb5cc91-d89e-4703-ab3a-91c94072d7aa","order_by":13,"name":"Damien Todjinou","email":"","orcid":"","institution":"Centre de Recherches Entomologiques de Cotonou (CREC)","correspondingAuthor":false,"prefix":"","firstName":"Damien","middleName":"","lastName":"Todjinou","suffix":""},{"id":335850143,"identity":"aecb1eba-64e1-4b26-8793-e0987a6a92bc","order_by":14,"name":"Renaud Govoetchan","email":"","orcid":"","institution":"London School of Hygiene and Tropical Medicine (LSHTM)","correspondingAuthor":false,"prefix":"","firstName":"Renaud","middleName":"","lastName":"Govoetchan","suffix":""},{"id":335850148,"identity":"46b51f64-b68f-4504-94d0-b1f87ffc218e","order_by":15,"name":"Germain Gil Padonou","email":"","orcid":"","institution":"Centre de Recherches Entomologiques de Cotonou (CREC)","correspondingAuthor":false,"prefix":"","firstName":"Germain","middleName":"Gil","lastName":"Padonou","suffix":""},{"id":335850151,"identity":"a3d03262-86fb-4fdc-9f07-4bcdd7192373","order_by":16,"name":"Martin Akogbeto","email":"","orcid":"","institution":"Centre de Recherches Entomologiques de Cotonou (CREC)","correspondingAuthor":false,"prefix":"","firstName":"Martin","middleName":"","lastName":"Akogbeto","suffix":""}],"badges":[],"createdAt":"2024-07-22 13:34:01","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-4782261/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-4782261/v1","draftVersion":[],"editorialEvents":[{"content":"https://doi.org/10.1186/s13071-024-06504-1","type":"published","date":"2024-10-07T15:57:31+00:00"}],"editorialNote":"","failedWorkflow":false,"files":[{"id":62142261,"identity":"fbbbd38d-ba67-4a8b-8905-2481ef08c36c","added_by":"auto","created_at":"2024-08-09 17:40:14","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":903992,"visible":true,"origin":"","legend":"\u003cp\u003eMap of study area of cluster randomized controlled trial showing ITN durability assessment clusters. \u003cem\u003eTen clusters were randomly selected from each study arm.\u003c/em\u003e\u003c/p\u003e","description":"","filename":"floatimage1.png","url":"https://assets-eu.researchsquare.com/files/rs-4782261/v1/1f906f205b41ce9517a359f2.png"},{"id":62142258,"identity":"14bb1e0f-374d-406b-9378-ad69574dc8a9","added_by":"auto","created_at":"2024-08-09 17:40:13","extension":"jpeg","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":440717,"visible":true,"origin":"","legend":"\u003cp\u003eProportionate hole index of study nets at each survey timepoint.\u003c/p\u003e","description":"","filename":"floatimage2.jpeg","url":"https://assets-eu.researchsquare.com/files/rs-4782261/v1/742b0fc072356dcdd40e0747.jpeg"},{"id":62142256,"identity":"b53156dc-5620-4b82-bfa1-6d1306d85be2","added_by":"auto","created_at":"2024-08-09 17:40:13","extension":"png","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":38275,"visible":true,"origin":"","legend":"\u003cp\u003eReasons for attrition of study nets at each survey timepoint. \u003cem\u003eAttrition was classified as a) due to wear and tear (physical damage, b) due to the net being given away, stolen, sold or used in another location (removal) and c) due to the net being used for other purposes (repurposed).\u003c/em\u003e\u003c/p\u003e","description":"","filename":"OnlineFigure3reasonsforITNloss.png","url":"https://assets-eu.researchsquare.com/files/rs-4782261/v1/557969b765c4d50b87885efa.png"},{"id":62142253,"identity":"80515b95-e16c-4a68-ab24-8d6eb468f2df","added_by":"auto","created_at":"2024-08-09 17:40:13","extension":"png","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":28530,"visible":true,"origin":"","legend":"\u003cp\u003eProportion of study nets hanging over sleeping places at each survey time point.\u003c/p\u003e","description":"","filename":"OnlineFigure4ITNhangingrate.png","url":"https://assets-eu.researchsquare.com/files/rs-4782261/v1/d3658a4dde6de5f404026a68.png"},{"id":62142259,"identity":"483fecf6-aae6-4fca-8d41-c74a3bc47919","added_by":"auto","created_at":"2024-08-09 17:40:14","extension":"png","order_by":5,"title":"Figure 5","display":"","copyAsset":false,"role":"figure","size":28108,"visible":true,"origin":"","legend":"\u003cp\u003eSusceptibility of pyrethroid-resistant \u003cem\u003eAn coluzzii \u003c/em\u003eAkron strain to insecticides applied on study nets. Approximately 100 mosquities were exposed to each insecticide at each timepoint.\u003c/p\u003e","description":"","filename":"OnlineFigure5Akronsusceptibility.png","url":"https://assets-eu.researchsquare.com/files/rs-4782261/v1/98fabe4d4db4d41b3754e526.png"},{"id":62142624,"identity":"735089e6-b543-4e58-aaa7-5a22c37f102f","added_by":"auto","created_at":"2024-08-09 17:48:14","extension":"png","order_by":6,"title":"Figure 6","display":"","copyAsset":false,"role":"figure","size":35376,"visible":true,"origin":"","legend":"\u003cp\u003eProportion of ITNs that passed WHO efficacy criteria in laboratory bioassays for each active ingredient tested. \u003cem\u003eInterceptor® was tested against the susceptible Kisumu strain for alphacypermethrin bioefficacy in cone bioassays, Royal Guard® was tested against the susceptible Kisumu strain for alphacypermethrin bioefficacy in cone bioassays and against blood-fed pyrethroid-resistant Akron strain for pyriproxyfen bioefficacy in cone tested while Interceptor® G2 was tested against the pyrethroid-resistant Akron strain in tunnel tests. Each bar represents a sample size of 30 mosquito nets. Bars bearing the same letter label are not significantly different (p\u0026gt;0.05, chi-square test)\u003c/em\u003e\u003c/p\u003e","description":"","filename":"OnlineFigure6ITNpassrate.png","url":"https://assets-eu.researchsquare.com/files/rs-4782261/v1/e94222a1a923e3cbc67614fc.png"},{"id":62142255,"identity":"a82c1bbf-d081-48ee-aa99-7fff9eed1fb9","added_by":"auto","created_at":"2024-08-09 17:40:13","extension":"png","order_by":7,"title":"Figure 7","display":"","copyAsset":false,"role":"figure","size":30197,"visible":true,"origin":"","legend":"\u003cp\u003ePercentage retention of AI content of study nets over time\u003c/p\u003e","description":"","filename":"OnlineFigure7AIretentionrate.png","url":"https://assets-eu.researchsquare.com/files/rs-4782261/v1/99af1d04444fb7d76771fc4c.png"},{"id":66597593,"identity":"f89f7d88-b221-4a2b-8db2-6e1691b44cd0","added_by":"auto","created_at":"2024-10-14 16:11:05","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":2907969,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-4782261/v1/882cf8d2-8c7b-49fd-90de-4055b0d72301.pdf"},{"id":62142623,"identity":"195c8e2c-e3ee-4e9e-8ca1-0af21d4028f4","added_by":"auto","created_at":"2024-08-09 17:48:13","extension":"docx","order_by":9,"title":"","display":"","copyAsset":false,"role":"supplement","size":17541,"visible":true,"origin":"","legend":"","description":"","filename":"Supplementaryinformation.docx","url":"https://assets-eu.researchsquare.com/files/rs-4782261/v1/977553727a5130fc6f7d22dd.docx"}],"financialInterests":"No competing interests reported.","formattedTitle":"The physical and insecticidal durability of two dual active ingredient nets (Interceptor® G2 and Royal Guard®) in Benin, West Africa; results for a durability study embedded in a cluster randomised controlled trial","fulltext":[{"header":"Background","content":"\u003cp\u003eThe large-scale deployment of insecticide-treated nets (ITNs) via tri-annual mass campaigns is the main malaria prevention and control strategy deployed in most endemic countries in sub-Saharan Africa. While ITNs have played a major role in reducing the burden of malaria globally [\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e], their impact is threatened by their poor retention and use by householders, poor durability of the fabric and insecticide applied to them and the development of vector resistance to pyrethroids \u0026ndash; the main insecticide used on ITNs [\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e]. To optimize the impact of ITNs for malaria control, high levels of coverage of the target communities must be achieved, householders must retain and use them, and the nets should maintain their efficacy against mosquito vectors until the next campaign cycle [\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e]. By contrast, several studies have shown that ITNs are discarded more quickly than the 3 years presumed by country policies with most endemic African countries showing a median ITN retention time of \u0026lt;\u0026thinsp;2 years [\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e]. ITN retention rates vary widely from one community to another driven by several factors including the durability of the fabric, usage patterns and perceived efficacy by householders [\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e]. To help inform programmatic decision-making for procurements and replacement of worn-out nets, the WHO has established guidelines for investigating the durability of ITNs under operational conditions [\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e]. After distribution, ITNs are followed longitudinally to investigate their survivorship, fabric integrity and insecticidal activity using well-defined procedures.\u003c/p\u003e \u003cp\u003eSeveral studies have reported poor entomological performance of pyrethroid-only ITNs in areas where vectors are resistant to pyrethroids. Dual active ingredient nets treated with a mixture of a pyrethroid and a non-pyrethroid compound capable of providing enhanced control of pyrethroid-resistant vectors were recently developed to help mitigate this threat. Nets treated with pyrethroids and the pyrrole chlorfenapyr or the insect growth regulator pyriproxyfen were endorsed by the WHO in 2023 [\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e] after demonstrating improved public health value over 2 years of use in cRCT across Africa [\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e, \u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e]. Based on the findings from these trials, the WHO issued a strong recommendation for the deployment of pyrethroid-chlorfenapyr ITNs and a conditional recommendation for the deployment of pyrethroid-pyriproxyfen nets instead of pyrethroid-only nets in areas of pyrethroid resistance [\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e]. Following this endorsement, the proportion of these nets deployed in SSA is projected to increase substantially with pyrethroid-chlorfenapyr nets potentially replacing pyrethroid-only nets [\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e]. As the uptake of dual active ingredient nets increases, studies monitoring their durability should be performed in different settings to inform decision-making for their procurement and replacement by control programmes. WHO guidelines for assessing the attrition, fabric integrity, chemical content and insecticidal durability of ITNs under operational use [\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e, \u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e] were initially developed when pyrethroids were the only insecticides applied on ITNs and are being updated to cover new dual AI ITNs. This includes identifying standardised high throughput methods and suitable mosquito strains for testing the insecticidal durability of non-pyrethroid insecticides like chlorfenapyr and pyriproxyfen on nets. Unlike pyrethroids that knockdown and kill mosquitoes, chlorfenapyr is a pyrrole insecticide that acts on the insect mitochondria to slowly induce death [\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e] while pyriproxyfen is an insect growth regulator that sterilises adult female mosquitoes leading to a substantial reduction in offspring [\u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e, \u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eLike most malaria-endemic African countries, many ITN brands show poor durability in Benin. Indeed, a recent statistical inference study reported a low median ITN retention rate of ~\u0026thinsp;1.4 years for Benin, among the bottom six of the forty malaria-endemic African countries included in the study [\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e]. To investigate the durability of dual active ingredient nets in Benin, we nested a prospective cohort study in a cRCTs conducted in the Zou region of the country between 2020 and 2023 to compare the durability of a pyrethroid chlorfenapyr ITN (Interceptor\u0026reg; G2) and a pyrethroid-pyriproxyfen ITN (Royal Guard) to a pyrethroid-only ITN (Interceptor). We marked two cohorts of nets at baseline in 10 clusters in each arm of the cRCT and surveyed them every 6\u0026ndash;12 months to assess ITN attrition rate, fabric integrity, insecticidal efficacy and chemical content over 3 years of household use.\u003c/p\u003e"},{"header":"Materials and methods","content":"\u003cdiv id=\"Sec3\" class=\"Section2\"\u003e \u003ch2\u003eStudy area\u003c/h2\u003e \u003cp\u003eThe ITN durability study was performed in the Cove, Zagnanado, and Ouinhi Districts (COZO), of the Zou department of central Benin (7\u0026deg;11\u0026prime;N 1\u0026deg;59\u0026prime;E) between March 2020 and November 2023. The study was nested in a cRCT evaluating the efficacy of dual active ingredient nets for the control of clinical malaria compared to a pyrethroid-only net [\u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e, \u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e]. The study area consisted of 123 villages with approximately 54,000 households and a population size of 220,000 inhabitants. It has two rainy seasons (May-July and September-November) though malaria transmission occurs year-round. A baseline survey performed in 2019 prior to the cRCT showed a high malaria infection prevalence of 43.5% despite high ITN use (96%) [\u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e]. The vector population consists of both \u003cem\u003eAnopheles gambiae\u003c/em\u003e and \u003cem\u003eAnopheles coluzzii\u003c/em\u003e and is characterized by a high intensity of resistance to pyrethroids and susceptibility to chlorfenapyr and pyriproxyfen [\u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e]. The main economic activities carried out by the population are agriculture, fishing, hunting, trade, and hospitality.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec4\" class=\"Section2\"\u003e \u003ch2\u003eStudy arms\u003c/h2\u003e \u003cp\u003eThree different ITN types consisting of the 3 arms of the cRCT were evaluated in the durability study; two dual active ingredient nets (Interceptor\u0026reg; G2 and Royal Guard\u0026reg;) were compared to a standard pyrethroid-only ITN (Interceptor\u0026reg;). A description of the specifications of the three ITN types is provided below:\u003c/p\u003e \u003cp\u003e \u003col\u003e \u003cspan\u003e \u003cli\u003e \u003cp\u003eInterceptor\u0026reg; G2 (BASF AGRO B.V.), is a WHO-prequalified 100-denier, polyester ITN coated with a mixture of alpha-cypermethrin and chlorfenapyr at target concentrations of 100 mg/m\u003csup\u003e2\u003c/sup\u003e (\u0026plusmn;\u0026thinsp;25%) and 200 mg/m\u003csup\u003e2\u003c/sup\u003e (\u0026plusmn;\u0026thinsp;25%) respectively. The bursting strength of the fabric is \u0026ge;\u0026thinsp;405 kPa while the mass per unit area is 40 g/m\u0026sup2; (\u0026plusmn;\u0026thinsp;10%) for 100 denier yarn.\u003c/p\u003e \u003c/li\u003e \u003c/span\u003e \u003cspan\u003e \u003cli\u003e \u003cp\u003eRoyal Guard\u0026reg; (Disease Control Technologies, LLC, USA), is a WHO-prequalified 150-denier, polyethylene ITN incorporated with a mixture of alpha-cypermethrin and pyriproxyfen at target concentrations of 225 mg/m\u003csup\u003e2\u003c/sup\u003e (\u0026plusmn;\u0026thinsp;25%) and 225 mg/m\u003csup\u003e2\u003c/sup\u003e (\u0026plusmn;\u0026thinsp;25%) respectively. The bursting strength of the fabric is \u0026ge;\u0026thinsp;450 kPa while the mass per unit area is 45 g/m\u0026sup2; (\u0026plusmn;\u0026thinsp;10%) for 150 denier yarn.\u003c/p\u003e \u003c/li\u003e \u003c/span\u003e \u003cspan\u003e \u003cli\u003e \u003cp\u003eInterceptor\u0026reg; (BASF AGRO B.V.), is a WHO-prequalified 100-denier, polyester ITN coated with alpha-cypermethrin at target concentrations of 200 mg/m\u003csup\u003e2\u003c/sup\u003e (\u0026plusmn;\u0026thinsp;25%). The bursting strength of the fabric is \u0026ge;\u0026thinsp;405 kPa while the mass per unit area is 40 g/m\u0026sup2; (\u0026plusmn;\u0026thinsp;10%) for 100 denier yarn. Interceptor\u0026reg; is the control arm of the trial against which Interceptor\u0026reg; G2 and Royal Guard\u0026reg; are compared.\u003c/p\u003e \u003c/li\u003e \u003c/span\u003e \u003c/ol\u003e \u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec5\" class=\"Section2\"\u003e \u003ch2\u003eStudy design\u003c/h2\u003e \u003cp\u003e \u003cdiv class=\"BlockQuote\"\u003e \u003cp\u003eThe study design has been described in detail previously [\u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e]. Participating households were blinded to the type of ITN they received while field data collectors were blinded to the allocation of households to study arms. Ten out of 20 clusters of each study arm of the cRCT were randomly selected for the durability assessment (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e). Following ITN distribution, households were visited in these clusters to recruit and prospectively follow 2 separate cohorts of ITNs per arm (Cohorts 1 and 2) every 6\u0026ndash;12 months to monitor their physical and insecticidal durability over 36 months. Cohort 1 consisted of a total of 2,428 nets from 348\u0026ndash;391 randomly selected households in 5 clusters per study arm. These nets were followed for ITN survivorship and fabric integrity at 6-, 12-, 24-, 30- and 36 months post ITN distribution. Cohort 2 consisted of 1860 nets per study arm from 593 households from all 10 randomly selected clusters (~\u0026thinsp;60 households per cluster) per study arm that were withdrawn (and replaced with new nets) for assessment of insecticidal activity in laboratory bioassays and experimental hut trials, the content of each active ingredient and for other studies. Cohort 1 and Cohort 2 nets received separate identification numbers and were sampled from different households to prevent the risk of destructive sampling of nets intended for ITN survivorship studies (cohort 1).\u003c/p\u003e \u003c/div\u003e \u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec6\" class=\"Section2\"\u003e \u003ch2\u003eHousehold sensitisation and marking of study nets\u003c/h2\u003e \u003cp\u003eITNs were recruited for the durability study in the first month after ITN distribution from selected clusters of each arm of the cRCT using the ITN distribution list of the trial. Field workers visited selected households for each cohort of ITNs to mark study nets available in them. Using a wash-resistant marker, a unique code was written on the study net to indicate the study arm, cluster ID, household ID and the cohort to which it belonged. During this visit, the study team explained the durability study to the householders in their local language and assisted them in hanging up their nets if needed. Only nets that were hung up and in use at the start of the trial were included. The GPS coordinates and characteristics of each household included in the durability assessment were also recorded.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec7\" class=\"Section2\"\u003e \u003ch2\u003eITN attrition and fabric integrity (cohort 1)\u003c/h2\u003e \u003cp\u003eHouseholds in cohort 1 were visited at 6-, 12-, 24- and 36-months post ITN distribution and nets were assessed for attrition and fabric integrity at each time point. Attrition was assessed by recording the physical presence/absence of each net that was recruited in the household. Where a net was not found, the householder was asked about the reason for the loss of the net e.g given away, sold, stolen, worn out and disposed of etc. Attrition was classified into 3 categories; a) due to physical damage (wear and tear), b) due to the net being removed (given away, stolen, sold or used in another location) and c) due to the net being used for other purposes (repurposed). Nets that had never been used were recorded and excluded from the analysis. At each time point, all available cohort 1 ITNs of each type were assessed for fabric integrity (hole index) and condition. A minimum of 250 nets were assessed and to ensure this number, cohort 2 nets were also assessed for fabric integrity when available cohort 1 nets were insufficient. The survey team inspected the nets outside in broad daylight to determine the hole index using a portable frame over which the net was draped during the inspection. The nets were returned to the family right after the inspection.\u003c/p\u003e \u003cp\u003eThe number of holes and hole sizes on each ITN panel was measured using hole assessment sheets and classified into 4 sizes (size 1: 0.5-2cm, Size 2: 2\u0026ndash;10 cm, Size 3: 10-25cm, and size 4: \u0026gt;25cm). Physical integrity was measured as the proportionate hole index (pHI) which was calculated as pHI = (1 \u0026times; number of size 1 holes) + (23 \u0026times; number of size 2 holes) + (196 \u0026times; number of size 3 holes) + (576 \u0026times; number of size 4 holes). Nets were then categorized based on recommended cut-off points for pHI into \u0026ldquo;good\u0026rdquo; condition (pHI 0\u0026ndash;64), \u0026ldquo;acceptable\u0026rdquo; condition (pHI 65\u0026ndash;642) and \u0026ldquo;torn\u0026rdquo; (pHI 643+) defined in WHO guidelines [\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eTo determine the proportion of study nets that were in active use at each time point, we recorded the proportion of nets that were found hanging over sleeping places during each survey. Previous studies in Benin have indicated that householders usually have spare new ITNs from previous campaigns or routine distribution channels in their possession (unpublished data) which may affect the frequency with which the study nets are discarded. At 24 months, 362 participating households that had lost their study nets were further surveyed to identify the number, type and sources of non-study nets that they had replaced their study nets with. Householders were also administered a short questionnaire to determine what ITN fabric texture type (polyester vs. polyethylene) they preferred and to provide reasons why. They were shown examples of the two ITN fabric types and allowed to touch them before providing their responses.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec8\" class=\"Section2\"\u003e \u003ch2\u003eITN bioefficacy and chemical analysis (cohort 2)\u003c/h2\u003e \u003cp\u003e \u003cdiv class=\"BlockQuote\"\u003e \u003cp\u003eFor each ITN type a total of 120 nets belonging to cohort 2 were randomly selected and destructively sampled from households at 6, 12, 24 and 36-months post-distribution for laboratory and chemical analysis (Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e). They were replaced with new nets of the same type at each sampling point. Thirty nets of each ITN type withdrawn at each timepoint were subjected to laboratory bioassays (WHO cone bioassays and tunnel tests where necessary) to monitor entomological efficacy against mosquito vectors and to chemical analysis to monitor changes in alphacypermethrin, chlorfenapyr and pyriproxyfen content. Four to five net pieces measuring 30x30cm cut from each ITN were tested in laboratory bioassays. A similar number of net pieces were obtained from adjacent positions to those for laboratory bioassays and preserved at 4\u003csup\u003e0\u003c/sup\u003e C for chemical analysis.\u003c/p\u003e \u003c/div\u003e \u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab1\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 1\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eNumber of Interceptor\u0026reg; G2, Royal Guard\u0026reg; and Interceptor\u0026reg; ITNs tested for bioefficacy and chemical content\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"5\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003eMonths post ITN distribution\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eNo. of ITNs tested in lab bioassays\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eNo. of pieces per ITN\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003eTotal number of pieces for bioassays\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c5\"\u003e \u003cp\u003eNo. of pieces for chemical analysis\u003csup\u003ea\u003c/sup\u003e\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e30\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e150\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e150\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e12\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e30\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e120\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e120\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e24\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e30\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e120\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e120\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e36\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e30\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e200\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e120\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eTotal\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e\u003cb\u003e120\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e\u003cb\u003e590\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e\u003cb\u003e510\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cp\u003e \u003csup\u003e \u003cem\u003ea\u003c/em\u003e \u003c/sup\u003e \u003cem\u003eNet pieces preserved for chemical analysis were obtained from adjacent positions on the same ITNs cut for bioassays.\u003c/em\u003e \u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec9\" class=\"Section2\"\u003e \u003ch2\u003eMosquito strains for laboratory bioassays\u003c/h2\u003e \u003cp\u003eCone bioassays and tunnel tests were performed to monitor the bioefficacy of each AI in each ITN brand using laboratory-reared susceptible and pyrethroid-resistant strains of \u003cem\u003eAnopheles gambiae\u003c/em\u003e s.l.. All strains were maintained at CREC/LSHTM insectary in Cotonou, Benin. The characteristic of each strain is described below.\u003c/p\u003e \u003cp\u003e \u003cul\u003e \u003cli\u003e \u003cp\u003e \u003cem\u003eAn. gambiae\u003c/em\u003e sensu stricto Kisumu, an insecticide-susceptible reference strain originating from the Kisumu area in Kenya and was colonised at the CREC/LSHTM insectary.\u003c/p\u003e \u003c/li\u003e \u003cli\u003e \u003cp\u003e \u003cem\u003eAn. coluzzii\u003c/em\u003e Akron, a pyrethroid and carbamate resistant strain originating from Akron (9\u0026deg;19\u0026prime;N2\u0026deg;18\u0026prime;E), Southern Benin, and maintained at CREC/LSHTM insectary. Resistance is mediated by target site mutations (L1014F \u003cem\u003ekdr\u003c/em\u003e and \u003cem\u003eAce-1R\u003c/em\u003e) and overexpressed cytochrome P450 enzymes [\u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e20\u003c/span\u003e].\u003c/p\u003e \u003c/li\u003e \u003c/ul\u003e \u003c/p\u003e \u003cp\u003eWHO susceptibility bioassays were performed during each round of bioassays to confirm the susceptibility status of each mosquito strain to the insecticides used on the nets. At each time point, approximately 100 mosquitoes of each strain were exposed in batches of 25 in WHO bottle bioassays treated with alpha-cypermethrin (0.05%), chlorfenapyr (100\u0026micro;g) and pyriproxyfen (100\u0026micro;g). For alpha-cypermethrin and chlorfenapyr unfed 2\u0026ndash;5 days-old mosquitoes were exposed for 1 hour and mortality was recorded after 24h for alpha-cypemethrin and 72h after exposure to chlorfenapyr. For pyriproxyfen, blood-fed 5\u0026ndash;8 days old mosquitoes were exposed for 1 hour in treated bottles and survivors were dissected 3 days later to measure the proportional reduction in fertility relative to the control unexposed mosquitoes as described previously [\u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e21\u003c/span\u003e]. The bioassays were performed at a temperature of 27\u0026deg;C\u0026thinsp;\u0026plusmn;\u0026thinsp;2\u0026deg;C and a relative humidity of 75% \u0026plusmn; 10%.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec10\" class=\"Section2\"\u003e \u003ch2\u003eLaboratory bioassay methods\u003c/h2\u003e \u003cp\u003eIn line with the existing WHO guidelines [\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e, \u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e], ITN bioefficacy at each timepoint was expressed in terms of the proportion of ITNs passing pre-determined efficacy criteria for each active ingredient in cone bioassays or tunnel tests. Table \u003cspan refid=\"MOESM1\" class=\"InternalRef\"\u003eS1\u003c/span\u003e summarises the methods and strains used to assess the efficacy of each active ingredient in each ITN type. All bioassays were performed at 27\u0026thinsp;\u0026plusmn;\u0026thinsp;2\u0026deg;C and 75% \u0026plusmn; 10% relative humidity.\u003c/p\u003e \u003cp\u003e \u003cstrong\u003eBioefficacy of alphacypermethrin in Interceptor\u0026reg; and Royal Guard\u0026reg;\u003c/strong\u003e \u003cp\u003eFollowing WHO guidelines for testing the durability of the bioefficacy of pyrethroid-treated ITNs, the efficacy of alpha-cypermethrin in Interceptor\u0026reg; and Royal Guard\u0026reg; was monitored in 3-minute cone bioassays using unfed 3\u0026ndash;5 days old mosquitoes of the susceptible \u003cem\u003eAn gambiae\u003c/em\u003e Kisumu strain. At each time point, 40\u0026ndash;50 mosquitoes were exposed to each ITN in replicates of ~\u0026thinsp;5 mosquitoes per cone and 2 cones per ITN piece. ITNs that failed to achieve WHO efficacy criteria in these cone bioassays (pooled knock-down \u0026ge;\u0026thinsp;95% or pooled 24hrs mortality\u0026thinsp;\u0026ge;\u0026thinsp;80%) were subjected to tunnel tests. For each ITN that failed in cone bioassays, only one ITN piece (with cone bioassay mortality that is closest to the mean) was tested in tunnels. Approximately 100 unfed 5\u0026ndash;8 days old susceptible \u003cem\u003eAn gambiae\u003c/em\u003e Kisumu were exposed to each ITN piece in the tunnel tests and efficacy of alpha-cypermethrin in Interceptor\u0026reg; and Royal Guard\u0026reg; was measured in terms of mortality after 24hrs (\u0026ge;\u0026thinsp;80%) or blood-feeding inhibition (\u0026ge;\u0026thinsp;90%).\u003c/p\u003e \u003c/p\u003e \u003cp\u003e \u003cstrong\u003eBioefficacy of pyriproxyfen in Royal Guard\u0026reg;\u003c/strong\u003e \u003cp\u003eTo monitor the bioefficacy of pyriproxyfen in Royal Guard, blood-fed 5\u0026ndash;8 days old mosquitoes of the pyrethroid-resistant \u003cem\u003eAn coluzzii\u003c/em\u003e Akron strain were exposed for 3 minutes in cone bioassays and assessed for the impact on ovary development using dissection. Dissections were performed 72 hrs after exposure under a microscope and mosquitoes were classified as fertile or infertile following previously described SOPs [\u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e22\u003c/span\u003e]. A total of 80\u0026ndash;100 blood-fed mosquitoes were tested against each Royal Guard\u0026reg; ITN in replicates of 5 mosquitoes per cone and 4 cones per ITN piece and efficacy was measured for each ITN in terms of the proportional reduction in fertility relative to control unexposed mosquitoes. A cut off of \u0026ge;\u0026thinsp;50% reduction in fertility relative to the untreated control nets was applied to determine pass rates of Royal Guard\u0026reg; nets for pyriproxyfen bioefficacy. Only tests for which at least 30% of unexposed mosquitoes are found fertile were considered valid.\u003c/p\u003e \u003c/p\u003e \u003cp\u003e \u003cstrong\u003eBioefficacy of chlorfenapyr in Interceptor\u0026reg; G2\u003c/strong\u003e \u003cp\u003eThe bioefficacy of chlorfenapyr in Interceptor\u0026reg; G2 was assessed in tunnel tests using the pyrethroid-resistant Akron strain. To improve the efficiency of the tunnel test bioassays, only 1 ITN piece per whole Interceptor\u0026reg; G2 ITN was tested in tunnels. For each tunnel, a total of ~\u0026thinsp;100 unfed 5\u0026ndash;8 days old pyrethroid resistant \u003cem\u003eAn coluzzii\u003c/em\u003e Akron were exposed overnight and efficacy of Interceptor\u0026reg; G2 in tunnels was measured in terms of mosquito mortality after 72hrs (\u0026ge;\u0026thinsp;80%) or blood-feeding inhibition (\u0026ge;\u0026thinsp;90%).\u003c/p\u003e \u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec11\" class=\"Section2\"\u003e \u003ch2\u003eChemical analysis methods\u003c/h2\u003e \u003cp\u003eNet pieces preserved for chemical analysis at 0, 12, 24 and 36 months (510 pieces per ITN type) were wrapped in Aluminum foil and stored at 4\u003csup\u003e0\u003c/sup\u003eC (+/-2\u003csup\u003e0\u003c/sup\u003eC) and afterwards shipped to Centre Walloon de Recherches Agronomiques (CRA-W), Belgium, for detection of fabric weight and AI content. The methods used for AI extraction have been described elsewhere [\u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e, \u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e23\u003c/span\u003e]. Gas Chromatography with Flame Ionisation Detection (GC-FID) was used to determine the content of each AI. ITN pieces from the same net were pooled to provide a single chemical content reading per AI for each whole ITN per net type sampled at each time point.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec12\" class=\"Section2\"\u003e \u003ch2\u003eData management\u003c/h2\u003e \u003cp\u003eHousehold data collected during the census and ITN follow-up surveys were captured on electronic forms using smartphones installed with OpenDataKit (ODK) Collect while entomological data was recorded on data entry forms and double-entered pre-designed Excel databases. Throughout the study, electronic data was stored encrypted while paper forms were locked up in secured cabinets and were available only to study investigators and data management staff by passwords and keys. All personal data was anonymized using a unique identifier number for each participant and household to ensure confidentiality. At the end of the study, all electronic files and data entry forms have been respectively stored on the server and archive of the CREC-LSHTM GLP-certified Facility for 10 years.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec13\" class=\"Section2\"\u003e \u003ch2\u003eStatistical analysis\u003c/h2\u003e \u003cp\u003eData from the surveys at 6, 12, 24, 30 and 36 months was used to calculate attrition, functional survival and median survival time. Attrition was estimated at each time point as the proportion of study nets that were not found in households either due to physical damage, removal or repurposing relative to the number of nets distributed as a baseline after removing nets that were lost to follow-up. Functional survival was calculated at each survey time point as the proportion of nets in serviceable condition after excluding nets that were given away, sold or stolen. Median survival was calculated as the linear extrapolation of the survival values from either the 12- or 24-month rounds (whichever was \u0026lt;\u0026thinsp;85% survival) and the 36 months round to the y\u0026thinsp;=\u0026thinsp;50% line, using the following formula:\u003cdiv id=\"Equa\" class=\"Equation\"\u003e\u003cdiv format=\"TEX\" class=\"mathdisplay\" id=\"FileID_Equa\" name=\"EquationSource\"\u003e\n$$\\:Tm=t1+\\left(t2-t1\\right)*(p1-50)/(p1-p2)$$\u003c/div\u003e\u003c/div\u003e\u003c/p\u003e \u003cp\u003ewhere tm is the median survival time, t1 and t2 are the first and second timepoints in years and p1 and p2 are the proportions surviving to the first and second timepoints respectively in percent. Confidence intervals (CI) for this estimate were calculated by projecting the 95% CI from the survival estimates in the same way as described above. Hazard ratios (HRs) for the difference in functional survival and 95% confidence intervals were predicted using Cox proportional regression models. A chi-squared test was used to assess the proportion of nets of each ITN type passing the WHO criteria for alphacypermethrin, chlorfenapyr and pyriproxyfen bioefficacy based on combined cone and tunnel tests.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec14\" class=\"Section2\"\u003e \u003ch2\u003eEthical considerations\u003c/h2\u003e \u003cp\u003e \u003cstrong\u003eEthical approval\u003c/strong\u003e \u003cp\u003e was obtained from the ethics review boards of the Ministry of Health in Benin (N\u0026deg;6/30/MS/DC/DRFMT/CNERS/SA), the institutional review board of the London School of Hygiene and Tropical Medicine (N\u0026deg;16,237), and the WHO Research Ethics Review Committee (ERC.0003153). The cRCT is registered on clinicaltrials.gov (NCT03931473) and the study protocol was published before the start of the trial [\u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e]. Heads of households selected for the durability study gave informed consent prior to their participation. The consent form was written in French and explained to them in their local language. Where the individual was unable to read or write, their fingerprint was taken, and a signature obtained from a witness to the informed consent procedure. All personal data was anonymised prior to data processing. Approval for use of guinea pigs for tunnel tests was obtained from the LSHTM Animal Welfare Ethics Review Board (Ref: 2020-01). The methods described in this paper were carried out following relevant guidelines and regulations.\u003c/p\u003e \u003c/p\u003e \u003c/div\u003e"},{"header":"Results","content":"\u003cdiv id=\"Sec16\" class=\"Section2\"\u003e \u003ch2\u003eITN survivorship, attrition rate and fabric integrity\u003c/h2\u003e \u003cdiv id=\"Sec17\" class=\"Section3\"\u003e \u003ch2\u003eITN survivorship\u003c/h2\u003e \u003cp\u003eA total of 2,428 ITNs were recruited at baseline consisting of 792 Interceptor, 820 Royal Guard\u0026reg; and 816 Interceptor\u0026reg; G2. Table\u0026nbsp;\u003cspan refid=\"Tab2\" class=\"InternalRef\"\u003e2\u003c/span\u003e provides details of the number of nets that were available at each time point and the ITN functional survival rate calculated as the proportion of nets that were found in serviceable condition. Functional survival declined across all ITN types over time and had reduced to \u0026lt;\u0026thinsp;20% at the 36-month follow-up. The fastest decline in functional survival was observed with Royal Guard\u0026reg; (38% at 24 months and 6% at 36 months). Median ITN survival time was highest with Interceptor\u0026reg; (2.3 years, 95% CI 2.2\u0026ndash;2.4 years, p\u0026thinsp;\u0026lt;\u0026thinsp;0.05, Table\u0026nbsp;\u003cspan refid=\"Tab3\" class=\"InternalRef\"\u003e3\u003c/span\u003e). Royal Guard\u0026reg; also showed a significantly lower median survival time relative to Interceptor\u0026reg; [1.6 years (1.4\u0026ndash;1.8 years) vs. 2.3 years (2.2\u0026ndash;2.4 years); HR\u0026thinsp;=\u0026thinsp;1.49, 95% CI\u0026thinsp;=\u0026thinsp;1.36\u0026ndash;1.66, p\u0026thinsp;\u0026lt;\u0026thinsp;0.001] and to Interceptor\u0026reg; G2 [1.6 years (1.4\u0026ndash;1.8 years) vs. 2.1 years (2.0-2.2 years); HR\u0026thinsp;=\u0026thinsp;1.33, 95% CI\u0026thinsp;=\u0026thinsp;1.20\u0026ndash;1.47, p\u0026thinsp;\u0026lt;\u0026thinsp;0.001].\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab2\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 2\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eFunctional survivorship of ITNs\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"6\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c6\" colnum=\"6\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eITN types\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eInterceptor\u0026reg;\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003eRoyal Guard\u0026reg;\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c5\"\u003e \u003cp\u003eInterceptor\u0026reg; G2\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c6\"\u003e \u003cp\u003eAll ITNs\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eITNs marked at baseline\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e792\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e816\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e820\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e2428\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\" morerows=\"4\" rowspan=\"5\"\u003e \u003cp\u003e\u003cb\u003e6 months\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eITNs available\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e696\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e635\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e698\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e2029\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e% Attrition (95% CI)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e12.1 (9.7\u0026ndash;14.4)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e22.2 (19.0-25.1)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e14.9 (12.2\u0026ndash;17.3)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e16.4 (14.8\u0026ndash;17.9)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eITNs in serviceable condition\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e680\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e607\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e662\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e1948\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eITNs given away\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e110\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e178\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e109\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e397\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e% Functional survival (95% CI)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e99.7 (98.9\u0026ndash;99.9)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e94.5 (92.5\u0026ndash;96.2)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e93.6 (91.6\u0026ndash;95.3)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e95.3 (94.9\u0026ndash;96.7)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\" morerows=\"4\" rowspan=\"5\"\u003e \u003cp\u003e\u003cb\u003e12 months\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eITNs available\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e587\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e465\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e573\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e1625\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e% Attrition (95% CI)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e25.9 (22.3\u0026ndash;28.9)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e43.0 (38.5\u0026ndash;46.4)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e30.1 (26.4\u0026ndash;33.3)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e33.1 (30.8\u0026ndash;34.9)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eITNs in serviceable condition\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e553\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e428\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e515\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e1496\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eITNs given away\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e216\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e278\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e201\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e695\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e% Functional survival (95% CI)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e96 (94.1\u0026ndash;97.5)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e79.0 (75.3\u0026ndash;82.3)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e83.7 (80.6\u0026ndash;86.6)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e86.3 (84.6\u0026ndash;87.9)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\" morerows=\"4\" rowspan=\"5\"\u003e \u003cp\u003e\u003cb\u003e24 months\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eITNs available\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e420\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e276\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e359\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e1055\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e% Attrition (95% CI)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e47.0 (42.2\u0026ndash;50.5)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e66.2 (60.6\u0026ndash;69.4)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e56.2 (51.1\u0026ndash;59.6)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e56.5 (53.6\u0026ndash;58.5)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eITNs in serviceable condition\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e370\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e222\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e299\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e891\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eITNs given away\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e216\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e238\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e271\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e725\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e% Functional survival (95% CI)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e64.2 (60.2\u0026ndash;68.2)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e38.1 (33.2\u0026ndash;42.2)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e54.9 (50.6\u0026ndash;59.1)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e52.3 (49.9\u0026ndash;54.7)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\" morerows=\"4\" rowspan=\"5\"\u003e \u003cp\u003e\u003cb\u003e30 months\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eITNs available\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e278\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e139\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e236\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e653\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e% Attrition (95% CI)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e64.9 (59.3\u0026ndash;68.2)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e83.0 (76.7\u0026ndash;85.6)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e71.2 (65.4\u0026ndash;74.3)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e73.1 (69.7\u0026ndash;74.9)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eITNs in serviceable condition\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e192\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e104\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e161\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e457\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eITNs given away\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e395\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e236\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e433\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e1064\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e% Functional survival (95% CI)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e48.3 (43.3\u0026ndash;53.4)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e17.8 (14.8\u0026ndash;21.1)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e42 (37.0\u0026ndash;47.2)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e33.5 (31.0\u0026ndash;36.1)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\" morerows=\"4\" rowspan=\"5\"\u003e \u003cp\u003e\u003cb\u003e36 months\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eITNs available\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e154\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e60\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e165\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e165\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e% Attrition (95% CI)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e80.6 (74.3\u0026ndash;83.3)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e92.6 (86.0-94.4)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e79.9 (73.8\u0026ndash;82.6)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e93.2 (89.4\u0026ndash;94.2)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eITNs in serviceable condition\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e135\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e45\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e131\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e131\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eITNs given away\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e495\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e333\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e540\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e540\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e% Functional survival (95% CI)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e19.5 (16.6\u0026ndash;22.7)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e6.2 (4.6\u0026ndash;8.2)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e18.4 (15.7\u0026ndash;21.5)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e14.6 (13.2\u0026ndash;16.2)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab3\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 3\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eMedian survival times\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"4\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eMedian survival time (95% CI)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eHazard Ratio (95% CI)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003eP-value\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eInterceptor\u0026reg;\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e2.3 (2.2\u0026ndash;2.4)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eN/A\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eRoyal Guard\u0026reg;\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e1.6 (1.4\u0026ndash;1.8)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e1.49 (1.36\u0026ndash;1.66)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003ep\u0026thinsp;\u0026lt;\u0026thinsp;0.001\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eInterceptor\u0026reg; G2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e2.1 (2.0-2.3)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e1.13 (1.02\u0026ndash;1.26\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003ep\u0026thinsp;=\u0026thinsp;0.027\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eAll ITNs\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e2.1 (2.0-2.1)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eN/A\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eN/A\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv id=\"Sec18\" class=\"Section2\"\u003e \u003ch2\u003eITN fabric integrity and proportionate hole index of study nets\u003c/h2\u003e \u003cp\u003eFigure \u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003e shows the proportionate hole index of nets that were found and assessed for fabric integrity at each time point. The proportion of nets that were found in good and acceptable condition relative to the numbers distributed at baseline had declined substantially over time and was \u0026lt;\u0026thinsp;40% at 24 months post-distribution. At 36 months, less than 20% were found in good or acceptable conditions relative to the numbers distributed at baseline.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec19\" class=\"Section2\"\u003e \u003ch2\u003eReasons for ITN attrition\u003c/h2\u003e \u003cp\u003eThe most common reason for ITN attrition in the first 24 months of the study was that the nets had been used elsewhere or given away to relatives (Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003e). The proportion of ITNs that were discarded due to physical damage was \u0026lt;\u0026thinsp;10% at 6 months and increased to 25\u0026ndash;45% at 24 months. By the 36-month survey, ~\u0026thinsp;80% of ITNs had been discarded due to physical damage.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec20\" class=\"Section2\"\u003e \u003ch2\u003eNon-study nets in use and ITN preference survey\u003c/h2\u003e \u003cp\u003eApproximately 50\u0026ndash;80% of study nets that were found and assessed at each timepoint were hanging over sleeping places indicating active use of the nets (Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003e). For Interceptor\u0026reg; G2, this proportion was \u0026gt;\u0026thinsp;70% at all time points. With Interceptor, the proportion hanging was relatively lower (at 6 and 12 months (50\u0026ndash;60%) but increased substantially at later time points. Royal Guard\u0026reg; generally showed low hanging rates of 50\u0026ndash;60% across all time points indicating a lower use rate. Table\u0026nbsp;\u003cspan refid=\"Tab4\" class=\"InternalRef\"\u003e4\u003c/span\u003e shows the number of non-study nets that were found hanging in households in each study arm that were surveyed at 24 months post-distribution to investigate the replacement of study nets with other ITN types. A total of 761 non-study nets were found in 362 surveyed houses and 75% of these nets were PermaNet\u0026reg; 2.0 nets that had been distributed in the previous ITN mass campaign. The highest proportion of non-study nets in use was found in households in the Royal Guard\u0026reg; arm (52%) indicating a higher replacement of Royal Guard\u0026reg; nets relative to Interceptor\u0026reg; G2 (14.3%) and Interceptor\u0026reg; (33.5%) nets. Of a total of 300 heads of households surveyed for ITN fabric texture preference, 96% indicated a preference for polyester net fabric over polyethylene net fabric. The polyester fabric texture was perceived to be softer, cooler and less abrasive on the skin compared to the polyethylene fabric texture. About 60% of householders believed that the polyethylene nets shrunk in size after washing compared to 4% for polyester nets.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab4\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 4\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eProportion of non-study nets in use per study arm\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"5\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eRoyal Guard\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eInterceptor G2\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003eInterceptor\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c5\"\u003e \u003cp\u003eTOTAL\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eN HH surveyed\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e138\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e110\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e114\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e362\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eN non-study nets in use\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e397\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e109\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e255\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e\u003cb\u003e761\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e% non-study nets in use\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e52.2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e14.3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e33.5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e100\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec21\" class=\"Section2\"\u003e \u003ch2\u003eBioefficacy in laboratory bioassays\u003c/h2\u003e \u003cdiv id=\"Sec22\" class=\"Section3\"\u003e \u003ch2\u003eSusceptibility of test strains\u003c/h2\u003e \u003cp\u003eFigure \u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e5\u003c/span\u003e presents annual results obtained in susceptibility bioassays performed with mosquito strains (Kisumu and Akron) tested against the study nets in the laboratory bioassays. For the Akron strain, during each year of the study, mortality in alpha-cypermethrin-treated tube tests remained\u0026thinsp;\u0026lt;\u0026thinsp;50% while mortality in chlorfenapyr-treated bottles remained\u0026thinsp;\u0026gt;\u0026thinsp;90% showing that the strain maintained its resistance to pyrethroids and susceptibility to chlorfenapyr. The reduction in fertility of Akron mosquitoes exposed to pyriproxyfen in bottle bioassays was also \u0026gt;\u0026thinsp;90% during each year of testing showing susceptibility to the insecticide throughout the study. Mortality in further bioassays performed with 5X and 10X the diagnostic dose of alpha-cypermethrin was \u0026lt;\u0026thinsp;95% at all timepoints showing that Akron strain had a high intensity of pyrethroid resistance throughout the study. Susceptibility bioassays performed with the Kisumu strain also showed that the strain remained susceptible to all three insecticides through the course of the study.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec23\" class=\"Section3\"\u003e \u003ch2\u003eBioefficacy results with Interceptor\u0026reg;\u003c/h2\u003e \u003cp\u003eA total of 7,627 susceptible \u003cem\u003eAn gambiae\u003c/em\u003e Kisumu mosquitoes were exposed to Interceptor\u0026reg; nets in 3 min cone bioassays at baseline and at 12, 24 and 36 months after household use. Overall mosquito mortality declined from 76.8% at baseline to 58.3% at 24 months and 44.4% at 36 months (Table\u0026nbsp;\u003cspan refid=\"Tab5\" class=\"InternalRef\"\u003e5\u003c/span\u003e). About half of the nets tested in cone bioassays failed to achieve WHO criteria in cone bioassays and were thus tested in tunnel tests. Mosquito mortality in tunnel tests was 98\u0026ndash;100% up to 12 months but declined to 53.7% at 24 months before rising to 87.4% at 36 months. Overall blood-feeding inhibition in tunnels generally exceeded 90% except at 24 months when it was 79.7%. Mortality with control untreated ITN pieces did not exceed 5% at any time point. Blood-feeding inhibition in tunnel tests was \u0026gt;\u0026thinsp;75% at each time point. All 30 Interceptor\u0026reg; ITNs passed efficacy criteria in either cone bioassays or tunnel tests at baseline and 12 months though the numbers passing reduced to 19 at 24 months and later increased to 27 at 36 months.\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab5\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 5\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eResults with Interceptor\u0026reg; nets tested against the susceptible Kisumu strain in cone bioassays and tunnel tests at baseline, 12, 24 and 36 months post-distribution. Only nets that failed WHO criteria in cone bioassays were tested in tunnels. \u003cem\u003eValues along a row bearing the same letter superscript are not significantly different (p\u0026thinsp;\u0026gt;\u0026thinsp;0.05, t-test)\u003c/em\u003e\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"5\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003eTreatments\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eBaseline\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003e12 months\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003e24 months\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c5\"\u003e \u003cp\u003e36 months\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eN ITNs Tested\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e30\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e30\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e30\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e30\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colspan=\"5\" nameend=\"c5\" namest=\"c1\"\u003e \u003cp\u003e\u003cb\u003eCone bioassay results\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eN pieces tested\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e150\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e120\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e120\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e120\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eN exposed\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e1530\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e1233\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e2326\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e2538\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eN KD\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e1394\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e1187\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e1961\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e1963\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eN dead\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e1175\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e934\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e1355\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e1126\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003e% KD (95% CI)\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e91.1 (86.3\u0026ndash;92.5)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e96.3 (90.8\u0026ndash;97.4)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e84.3 (80.6\u0026ndash;85.8)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e77.3 (73.9\u0026ndash;78.9)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003e% Dead (95% CI)\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e76.8 (72.4\u0026ndash;78.9)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e75.8 (70.9\u0026ndash;78.2)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e58.3 (55.2\u0026ndash;60.3)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e44.4 (41.8\u0026ndash;46.3)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colspan=\"5\" nameend=\"c5\" namest=\"c1\"\u003e \u003cp\u003e\u003cb\u003eTunnel test results with failed nets from cone bioassays\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eN pieces tested\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e14\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e15\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e16\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eN exposed\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e1589\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e543\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e1519\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e1602\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eN dead\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e1564\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e543\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e815\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e1400\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eN blood-fed\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e95\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e240\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e102\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003e% dead (95% CI)\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e98.4 (93.5\u0026ndash;99.0)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e100 (96\u0026ndash;100)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e53.7 (50.0-56.2)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e87.4 (82.8\u0026ndash;89.0)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003e% Blood-fed\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e6 (4.8\u0026ndash;7.2)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0.2\u0026nbsp;(0-0.6)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e15.8 (13.8\u0026ndash;17.6)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e6.4 (5.2\u0026ndash;7.6)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003e% BFI\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e92.3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e99.7\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e79.7\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e91.8\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eN ITN passing\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e30/30\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e30/30\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e19/30\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e27/30\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv id=\"Sec24\" class=\"Section2\"\u003e \u003ch2\u003eBioefficacy results with Royal Guard\u0026reg;\u003c/h2\u003e \u003cp\u003eResults obtained in bioassays investigating the bioefficacy of Royal Guard\u0026reg; are presented in Table\u0026nbsp;\u003cspan refid=\"Tab6\" class=\"InternalRef\"\u003e6\u003c/span\u003e. To assess the bioefficacy of alpha-cypermethrin in Royal Guard, a total of 8,363 susceptible \u003cem\u003eAn gambiae\u003c/em\u003e Kisumu mosquitoes were exposed to Royal Guard\u0026reg; nets in 3-minute cone bioassays at baseline and at 12, 24 and 36 months post-distribution. Overall mosquito mortality was \u0026gt;\u0026thinsp;90% at all time points of testing. All ITNs passed WHO criteria for alpha-cypermethrin efficiency in cone bioassays hence tunnel tests were not performed. A total of 1,966 blood-fed pyrethroid-resistant \u003cem\u003eAn coluzzii\u003c/em\u003e Akron mosquitoes that survived exposure to Royal Guard\u0026reg; nets in 3 min cone bioassays at baseline and 12, 24 and 36 months were dissected to investigate the bioefficacy of pyriproxyfen. The overall reduction in fertility rate was 99.3% at baseline but declined substantially\u0026thinsp;\u0026lt;\u0026thinsp;40% at 12 and 24 months and was 24.3% at 36 months. At each time point, mortality with control untreated net pieces did not exceed 5% at each time point and fertility rates with control unexposed mosquitoes were \u0026gt;\u0026thinsp;50%. All 30 Royal Guard\u0026reg; ITNs passed the criteria for alpha-cypermethrin bioefficacy at all time points. For pyriproxyfen bioefficacy, the number of Royal Guard\u0026reg; ITNs that passed efficacy criteria (\u0026gt;\u0026thinsp;50% reduction in fertility relative to control) was 30 at baseline and decreased substantially from 13 at 12 months to only 4 at 36 months.\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab6\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 6\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eResults with Royal Guard\u0026reg; nets tested in cone bioassays against susceptible Kisumu and blood-fed pyrethroid-resistant Akron strains at baseline, 12, 24 and 36 months post-distribution. \u003cem\u003eValues along a row bearing the same letter superscript are not significantly different (p\u0026thinsp;\u0026gt;\u0026thinsp;0.05, t-test)\u003c/em\u003e\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"5\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003eTreatments\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eBaseline\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003e12 months\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003e24 months\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c5\"\u003e \u003cp\u003e36 months\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eN ITNs Tested\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e30\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e30\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e30\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e30\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colspan=\"5\" nameend=\"c5\" namest=\"c1\"\u003e \u003cp\u003e\u003cb\u003eCone bioassays with Kisumu to investigate alpha-cypermethrin bioefficacy\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eN pieces tested\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e150\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e120\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e120\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e120\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eN exposed\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e1491\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e2351\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e2326\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e2468\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eN KD\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e1491\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e2345\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e2324\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e2434\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eN dead\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e1491\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e2315\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e2182\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e2378\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003e% KD (95% CI)\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e100.0 (96\u0026ndash;100)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e99.7 (95.7\u0026ndash;99.9)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e99.9 (95.8\u0026ndash;100)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e98.6 (94.7\u0026ndash;99.1)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003e% Dead (95% CI)\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e100 (96\u0026ndash;100)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e98.5 (94.5\u0026ndash;99.0)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e93.8 (89.9\u0026ndash;100)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e96.4 (92.5\u0026ndash;97.1)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eN ITNs passing\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e30/30\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e30/30\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e30/30\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e30/30\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colspan=\"5\" nameend=\"c5\" namest=\"c1\"\u003e \u003cp\u003e\u003cb\u003eCone bioassays with blood-fed Akron to investigate pyriproxyfen bioefficacy\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eN pieces tested\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e150\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e120\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e120\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e120\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eN exposed\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e2803\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e1152\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e2438\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e2480\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eN dissected\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e143\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e217\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e873\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e950\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eN fertile\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e138\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e551\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e707\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eN Unfertile\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e142\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e79\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e322\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e243\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003e% Fertile (95% CI)\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e0.7 (0.4-1.0)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e63.6 (59.0-66.4)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e63 (59.9\u0026ndash;64.9)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e74.4 (71.0-76.1)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003e% Reduction in fertility relative to control\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e99.3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e35.3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e36.0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e24.3\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eN ITNs passing\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e30/30\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e13/30\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e11/30\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e4/30\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cdiv id=\"Sec25\" class=\"Section3\"\u003e \u003ch2\u003eBioefficacy results with Interceptor\u0026reg; G2\u003c/h2\u003e \u003cp\u003eA total of 13,092 pyrethroid-resistant \u003cem\u003eAn coluzzii\u003c/em\u003e Akron mosquitoes were exposed to Interceptor\u0026reg; G2 nets in tunnel tests through the course of the study. Overall mosquito mortality was 95.7% at baseline and declined\u0026thinsp;\u0026lt;\u0026thinsp;80% at subsequent time points (Table\u0026nbsp;\u003cspan refid=\"Tab7\" class=\"InternalRef\"\u003e7\u003c/span\u003e). Blood-feeding inhibition did not exceed 90% at any time point and had declined to \u0026lt;\u0026thinsp;45% from 24 months onwards. Mortality in tunnel tests with control untreated net pieces did not exceed 10% while blood-feeding was \u0026gt;\u0026thinsp;50%. All 30 Interceptor\u0026reg; G2 nets passed the criteria for chlorfenapyr bioefficacy in tunnel tests at baseline though this number reduced to 19 at 12 months and was 6 and 8 at 24 and 36 months respectively.\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab7\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 7\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eResults with Interceptor\u0026reg; G2 nets tested in tunnel tests against the pyrethroid-resistant Akron strain at baseline, 12, 24 and 36 months post-distribution.\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"5\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003eTreatments\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eBaseline\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003e12 months\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003e24 months\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c5\"\u003e \u003cp\u003e36 months\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eN ITNs Tested\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e30\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e30\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e30\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e30\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eN pieces tested\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e30\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e30\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e30\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e30\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eN exposed\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e3258\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e3308\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e3308\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e3218\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eN dead\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e3118\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e2715\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e1711\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e1938\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eN blood-fed\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e686\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e1028\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e1831\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e1512\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003e% dead (95% CI)\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e95.7 (92.6\u0026ndash;96.7)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e82.1 (79.0-83.4)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e51.7 (49.3\u0026ndash;53.4)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e60.2 (49.22\u0026ndash;53.4)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003e% Blood-fed\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e21.1 (19.5\u0026ndash;22.5)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e31.1(29.2\u0026ndash;32.7)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e55.4 (52.8\u0026ndash;57.1)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e47 (44.6\u0026ndash;48.7)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003e% BFI\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e73.7\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e61.2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e31.0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e41.5\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eN ITNs passing\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e30/30\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e19/30\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e6/30\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e8/30\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec26\" class=\"Section3\"\u003e \u003ch2\u003eProportion of ITNs passing WHO criteria\u003c/h2\u003e \u003cp\u003eThe percentages of ITNs of each type that passed efficacy criteria for each active ingredient at each time point are presented in Fig.\u0026nbsp;\u003cspan refid=\"Fig6\" class=\"InternalRef\"\u003e6\u003c/span\u003e. ITN pass rate for bioefficacy of alpha-cypermethrin in Interceptor\u0026reg; was 100% at baseline and at 12 months though it declined to 65% at 24 months and later increased to 90% at 36 months. Royal Guard\u0026reg; showed 100% ITN pass rate for the bioefficacy of alpha-cypermethrin throughout the study meanwhile less than 40% of Royal Guard\u0026reg; and Interceptor\u0026reg; G2 ITNs withdrawn at 24 months passed efficacy criteria for pyriproxyfen and chlorfenapyr respectively. The proportion of ITNs passing bioefficacy criteria for pyriproxyfen in Royal Guard\u0026reg; and chlorfenapyr in Interceptor\u0026reg; G2 were generally similar at each time point (p\u0026thinsp;\u0026gt;\u0026thinsp;0.05). The results therefore showed a faster decline in bioefficacy of the non-pyrethroid insecticide compared to alpha-cypermethrin.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec27\" class=\"Section3\"\u003e \u003ch2\u003eChanges in chemical content over time\u003c/h2\u003e \u003cp\u003eThe mean active ingredient content was within target expectations for each ITN type at baseline (Table\u0026nbsp;8). For both dual active ingredient nets, greater amounts of alpha-cypermethrin were retained compared to the non-pyrethroid (Fig.\u0026nbsp;\u003cspan refid=\"Fig7\" class=\"InternalRef\"\u003e7\u003c/span\u003e). Over 50% of alpha-cypemethrin was still available in Royal Guard\u0026reg; nets at 36 months while the content of pyriproxyfen had reduced to 26% of the target. A similar trend was observed with Interceptor\u0026reg; G2 though the nets had lost\u0026thinsp;\u0026gt;\u0026thinsp;85% of their chlorfenapyr content at 36 months.\u003c/p\u003e \u003cp\u003e \u003cstrong\u003eTable\u0026nbsp;8\u003c/strong\u003e \u003cp\u003eChemical content (g/kg) of insecticide-treated nets withdrawn at 12-, 24- and 36-months post-distribution.\u003c/p\u003e \u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003c/div\u003e \u003c/div\u003e\u003cp\u003e\u003cimg src=\"https://myfiles.space/user_files/58854_b38fc7f3db2c487f/58854_custom_files/img1723224907.png\" width=\"1016\" height=\"446\"\u003e\u003cbr\u003e\u003c/p\u003e"},{"header":"Discussion","content":"\u003cp\u003e\u003cdiv class=\"BlockQuote\"\u003e\u003cp\u003eThis study evaluated the attrition, fabric integrity and insecticidal durability of two dual AI ITNs (Interceptor\u0026reg; G2 and Royal Guard\u0026reg;) compared to a WHO-prequalified alpha-cypermethrin net (Interceptor\u0026reg;) as part of cRCT performed in the Zou department of Benin between 2020 to 2023. ITN durability studies are essential for planning their replacement and for making programmatic and procurement decisions.\u003c/p\u003e\u003cp\u003eIn terms of ITN survivorship, the overall proportion of study nets available in households had reduced to 52% after 24 months and only 15% of nets were still available after 36 months. Overall ITN median survival time was 2.0 years which falls substantially below the 3-year durability assumed by the Benin NMCP\u0026rsquo;s policy of triannual ITN campaign cycles. ITN attrition due to physical damage was generally low during the first 2 years (\u0026lt;\u0026thinsp;25%) but increased substantially at the end point of the study (~\u0026thinsp;80%) indicating a significant loss in physical integrity of the study nets after 24 months of operational age. These findings align with the statistical inference study that reported poor ITN retention rates of \u0026lt;\u0026thinsp;2 years in most communities in Africa [\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e]. Nevertheless, an ITN coverage survey performed as part of the cRCT at 24 months showed that the study nets were mostly replaced by extra nets that householders still had in their possession from previous campaigns thus maintaining an overall high ITN coverage of \u0026gt;\u0026thinsp;90% in the study area [\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e]. This finding highlights the need for strategies to optimise ITN quantification and allocation to ensure equitable access across target populations [\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e].\u003c/p\u003e\u003cp\u003eComparing ITN survivorship between ITN types, the study demonstrated a higher median survival time for Interceptor\u0026reg; (2.3 years) and Interceptor\u0026reg; G2 (2.1 years) compared to Royal Guard\u0026reg; (1.6 years). This was further supported by the lower proportion of Royal Guard\u0026reg; nets hanging over sleeping places compared to Interceptor\u0026reg; and Interceptor\u0026reg; G2 and their increased replacement with other non-study nets. These findings can be attributed to differences in fabric type between the study nets; Interceptor\u0026reg; and Interceptor\u0026reg; G2 are made of polyester fabric while Royal Guard\u0026reg; is made of polyethylene fabric. Indeed, the qualitative survey performed 24 months post-distribution showed that householders overwhelmingly preferred ITNs made of polyester fabric due to their softer texture compared to ITNs made from polyethylene fabric which may have driven the higher replacement of Royal Guard\u0026reg; nets mostly with spare polyester nets (mainly PermaNet\u0026reg; 2.0) from the previous ITN campaigns. This may have contributed to the lack of an improved epidemiological impact with Royal Guard\u0026reg; relative to Interceptor\u0026reg; in the cRCT [\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e]. ITN users\u0026rsquo; low preference for the polyethylene ITN fabric texture has been demonstrated in multiple studies in Africa [\u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e24\u003c/span\u003e]. While an earlier study evaluating the durability of a polyethylene net (Olyset\u0026reg; Plus) distributed in Benin in 2010 reported a median survival time of just 2 years [\u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e25\u003c/span\u003e], more recent durability studies with polyester ITNs in Benin have shown longer median survival times of 2.8 years [\u003cspan citationid=\"CR26\" class=\"CitationRef\"\u003e26\u003c/span\u003e]. Although it has been argued that householders tend to use the net types that are available to them and that ITN use at the population level may not be affected by the user\u0026rsquo;s fabric texture preference [\u003cspan citationid=\"CR27\" class=\"CitationRef\"\u003e27\u003c/span\u003e], the findings from our study indicate that householders in Benin would be inclined to discard polyethylene nets more quickly compared to polyester nets. This finding supports the Benin NMCP\u0026rsquo;s policy of excluding polyethylene nets from their mass ITN campaigns. Given that the polyethylene fabric texture is more suitable for the application of some non-pyrethroid compounds on ITNs, strategies to improve the softness of polyethylene texture used for ITNs may help improve their acceptability and use by householders.\u003c/p\u003e\u003cp\u003eThe laboratory bioassays showed better retention of the bioefficacy of the pyrethroid component in the dual AI ITNs over 3 years of operational use compared to the non-pyrethroid component. The proportion of ITNs passing predetermined efficacy criteria in bioassays had reduced to \u0026lt;\u0026thinsp;40% at 24 months of operational age for pyriproxyfen in Royal Guard\u0026reg; and chlorfenapyr in Interceptor\u0026reg; G2 while 100% of Royal Guard\u0026reg; nets passed efficacy criteria for the pyrethroid component throughout the study. This can be explained by the higher loss rate of the non-pyrethroid active ingredients from the dual AI nets relative to the pyrethroid AI. Studies have also shown a significantly higher loss of PBO (\u0026gt;\u0026thinsp;80%) compared to pyrethroids on pyrethroid-PBO ITNs as they age under operational conditions [\u003cspan citationid=\"CR28\" class=\"CitationRef\"\u003e28\u003c/span\u003e, \u003cspan citationid=\"CR29\" class=\"CitationRef\"\u003e29\u003c/span\u003e, \u003cspan citationid=\"CR30\" class=\"CitationRef\"\u003e30\u003c/span\u003e]. This suggests that pyrethroids are generally more durable on ITNs than non-pyrethroid compounds used on existing dual AI nets. This further highlights the need for more innovative technologies to improve the insecticidal durability of non-pyrethroid AIs on mosquito nets.\u003c/p\u003e\u003cp\u003eAs new non-pyrethroid AIs are applied to ITNs, the methods and strains used for monitoring their bioefficacy under operational conditions must align with their mode of action. In this study, we modified existing WHO bioassays to allow assessment of the delayed toxic effects of chlorfenapyr on Interceptor\u0026reg; G2 using tunnel tests and the sterilising effects of pyriproxyfen on Royal Guard\u0026reg; by dissecting the ovaries of exposed blood-fed females. The bioassays provided interpretable results that aligned with changes in the content of the non-pyrethroid AIs over time. Bioassays that did not meet predefined validity criteria i.e cut-offs for mortality, blood-feeding or fertility in control unexposed mosquitoes were very rare. The susceptibility data also showed that the pyrethroid-resistant \u003cem\u003eAn coluzzii\u003c/em\u003e Akron strain that was used for bioefficacy testing of the non-pyrethroids maintained its resistance status throughout the study. This suggests that the methods used for monitoring the bioefficacy of both non-pyrethroid AIs over time were appropriate and could therefore contribute to the development of new WHO guidelines for investigating the bioefficacy of WHO-prequalified dual AI ITNs under long-term community use.\u003c/p\u003e\u003cp\u003eWhile the laboratory bioassays demonstrate how the bioefficacy of each ITN type changed over time, they do not provide a direct comparison between the ITN types given that different methods and mosquito strains had to be used to monitor changes in bioefficacy of each AI over time. Experimental hut trials were thus performed in parallel against wild free-flying pyrethroid-resistant malaria vectors in the Cove hut station with study nets withdrawn from households at 12, 24 and 36 months of operational age (unpublished data). The hut trial results have shown the superiority of Interceptor\u0026reg; G2 nets over other dual AI ITN types though the improved impact relative to Interceptor\u0026reg; had declined significantly with 24- and 36-months nets. This is supported by the substantial reduction in the proportion of Interceptor\u0026reg; G2 nets passing criteria for chlorfenapyr bioefficacy in the laboratory bioassays after 24 months in the present study relative to Interceptor\u0026reg; nets (\u0026lt;\u0026thinsp;30% \u003cem\u003evs\u003c/em\u003e 63\u0026ndash;90%). The reduced bioefficacy and chemical content of chlorfenapyr in Interceptor\u0026reg; G2 may therefore partly explain the loss of its improved epidemiological impact relative to Interceptor\u0026reg; in the third year of the cRCT [\u003cspan citationid=\"CR31\" class=\"CitationRef\"\u003e31\u003c/span\u003e]. Given the dependence of most malaria-endemic countries on triannual ITN campaigns for malaria prevention and control, innovative strategies and cost-effective interventions that can be deployed to improve vector control in the third-year post-ITN distribution are needed.\u003c/p\u003e\u003c/div\u003e\u003c/p\u003e"},{"header":"Conclusion","content":"\u003cp\u003eThis study demonstrated a median ITN survival time of 2.1 years for Interceptor\u0026reg; G2 and 1.6 years for Royal Guard\u0026reg; in communities in Benin. Royal Guard\u0026reg; nets were less used and discarded more quickly by householders partly due to their low preference for polyethylene nets relative to polyester nets. The insecticidal efficacy and content of the pyrethroid AI was more durable relative to the non-pyrethroid AIs in Interceptor\u0026reg; G2 and Royal Guard\u0026reg;. With Royal Guard\u0026reg;, all nets passed the bioefficacy criteria for the pyrethroid component at 36 months while only 14% passed the bioefficacy criteria for pyriproxyfen. With Interceptor\u0026reg; G2, only 25% of nets passed the bioefficacy criteria for chlorfenapyr at 36 months. The content of the non-pyrethroid insecticides at 36 months had reduced by 85% for chlorfenapyr in Interceptor\u0026reg; G2 and 73% for pyriproxyfen in Royal Guard\u0026reg; as opposed to 65% and 47% for the alphacypermethrin content respectively. The results corroborate the findings from the cRCT.\u003c/p\u003e"},{"header":"Abbreviations","content":"\u003cdiv class=\"DefinitionList\"\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003ePBO\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003ePiperonyl butoxide\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003eITN\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003eInsecticide-treated nets\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003eLLIN\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003eLong-lasting insecticidal nets\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003eWHO\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003eWorld Health Organization\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003ePQ\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003ePrequalification team\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003eAI\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003eActive ingredient\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003eGLP\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003eGood Laboratory Practice\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003ecRCT\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003eCluster randomised controlled trial\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003eSSA\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003eSub Saharan Africa\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003eNMCP\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003eNational Malaria Control Programme\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003eCREC\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003eCentre de Recherche Entomologique de Cotonou\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003eLSHTM\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003eLondon School of Hygiene \u0026amp; Tropical Medicine\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003ePAMVERC\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003ePan African Malaria Vector Research Consortium\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003c/div\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003cstrong\u003eEthical approval and consent to participate\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eEthical approval was obtained from the ethics review boards of the\u0026nbsp;Ministry of Health in Benin (N\u0026deg;6/30/MS/DC/DRFMT/CNERS/SA), the institutional review board of the London School of Hygiene and Tropical Medicine (N\u0026deg;16,237), and the WHO Research Ethics Review Committee (ERC.0003153). The cRCT is registered on clinicaltrials.gov (NCT03931473) and the study protocol was published before the start of the trial\u0026nbsp;[16].\u0026nbsp;Heads of households selected for the durability study gave informed consent prior to their participation. The consent form was written in French and explained to them in their local language. Where the individual was unable to read or write, their fingerprint was taken, and a signature obtained from a witness to the informed consent procedure. All personal data was anonymised prior to data processing.\u0026nbsp;Approval for use of guinea pigs for tunnel tests was obtained from the LSHTM Animal Welfare Ethics Review Board (Ref: 2020-01).\u0026nbsp;The\u0026nbsp;methods described in this paper were carried out following relevant guidelines and regulations.\u003c/p\u003e\n\u003cp\u003e\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConsent for publication\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eNot applicable\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eCompeting interests\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe authors declare that they have no competing interests.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eFunding\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThis study was supported by a grant to the London School of Hygiene and Tropical Medicine from Unitaid and The Global Fund through the Innovative Vector Control Consortium (IVCC). The third year of the trial was funded by the Net Transition Initiative of the Global Fund. The funders have no role in the study design, data collection and analysis and decision to publish this manuscript.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAuthors\u0026rsquo; contributions\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eC.N. designed the methods, was responsible for the overall conduct of the study and drafted the manuscript. A.F, and J.A. performed the field surveys with support from A.S. while E.D. supported data management. J.F. performed the laboratory bioassays supported by T.S. and R.G.. D.T. ensured the availability of test mosquitoes and performed the susceptibility bioassays. M.B. and O.P. performed the chemical analysis. C.N., A.F., J.F. and I.A. analysed the data and prepared the figures and tables. C.N., M.A., N.P., J.C., G.P. and M.C.A. were responsible for the management of the cluster randomized controlled trial and contributed to manuscript revision. All authors reviewed the manuscript.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAcknowledgements\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eWe thank Christen Fornadel of IVCC and Kate Kolaczinski of The Global Fund for project coordination. We also thank BASF and DCT for supplying the study nets and the community leaders and members of the Cove, Zagnanado and Ouinhi districts of the Zou region for their support and collaboration. We appreciate the National Malaria Control Programme of Benin for distributing the study nets and for their continuous support through the trial. \u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\u003cli\u003e\u003cspan\u003eBhatt S, Weiss D, Cameron E, Bisanzio D, Mappin B, Dalrymple U, et al. The effect of malaria control on Plasmodium falciparum in Africa between 2000 and 2015. Nature. 2015;526 7572:207\u0026ndash;11.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eWHO. World Malaria report. World Health Organisation, Geneva. 2023.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eKoenker H, Yukich J, Erskine M, Opoku R, Sternberg E, Kilian A. How many mosquito nets are needed to maintain universal coverage: an update. Malaria Journal. 2023;22 1:200; doi: \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1186/s12936-023-04609-z\u003c/span\u003e\u003cspan address=\"10.1186/s12936-023-04609-z\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e. https://doi.org/10.1186/s12936-023-04609-z.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eBertozzi-Villa A, Bever CA, Koenker H, Weiss DJ, Vargas-Ruiz C, Nandi AK, et al. Maps and metrics of insecticide-treated net access, use, and nets-per-capita in Africa from 2000\u0026ndash;2020. Nat Commun. 2021;12 1:3589; doi: \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1038/s41467-021-23707-7\u003c/span\u003e\u003cspan address=\"10.1038/s41467-021-23707-7\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eKilian A, Obi E, Mansiangi P, Ab\u0026iacute;lio AP, Haji KA, Blaufuss S, et al. Variation of physical durability between LLIN products and net use environments: summary of findings from four African countries. Malaria Journal. 2021;20 1:26; doi: \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1186/s12936-020-03549-2\u003c/span\u003e\u003cspan address=\"10.1186/s12936-020-03549-2\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e. https://doi.org/10.1186/s12936-020-03549-2.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eWHO. Guidelines for monitoring the durability of long-lasting insecticidal mosquito nets under operational conditions. Geneva, Switzerland: World Health Organization. 2011.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eWHO. Guidelines for malaria vector control. Geneva, Switzerland: World Health Organization. 2024.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eMosha JF, Kulkarni MA, Lukole E, Matowo NS, Pitt C, Messenger LA, et al. Effectiveness and cost-effectiveness against malaria of three types of dual-active-ingredient long-lasting insecticidal nets (LLINs) compared with pyrethroid-only LLINs in Tanzania: a four-arm, cluster-randomised trial. Lancet. 2022;399 10331:1227\u0026ndash;41; doi: \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1016/S0140-6736(21)02499-5\u003c/span\u003e\u003cspan address=\"10.1016/S0140-6736(21)02499-5\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://www.ncbi.nlm.nih.gov/pubmed/35339225\u003c/span\u003e\u003cspan address=\"https://www.ncbi.nlm.nih.gov/pubmed/35339225\" targettype=\"URL\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eAccrombessi M, Cook J, Dangbenon E, Yovogan B, Akpovi H, Sovi A, et al. Efficacy of pyriproxyfen-pyrethroid long-lasting insecticidal nets (LLINs) and chlorfenapyr-pyrethroid LLINs compared with pyrethroid-only LLINs for malaria control in Benin: a cluster-randomised, superiority trial. Lancet. 2023;401 10375:435\u0026ndash;46; doi: \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1016/s0140-6736(22)02319-4\u003c/span\u003e\u003cspan address=\"10.1016/s0140-6736(22)02319-4\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eAMP. Alliance for malaria prevention; mass campagn tracker. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://allianceformalariapreventioncom/mass-campaign-tracker/?_sfm_mc_date_of_import=20221015\u003c/span\u003e\u003cspan address=\"https://allianceformalariapreventioncom/mass-campaign-tracker/?_sfm_mc_date_of_import=20221015\" targettype=\"URL\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e. 2023;Accessed 28th October 2023.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eOrganization WH: Determination of fabric strength of long-lasting insecticidal nets: report of a WHO consultation, Geneva, 20\u0026ndash;22 August 2014. World Health Organization; 2015.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eWHO. Guidelines for laboratory and field testing of long-lasting insecticidal nets. Geneva, Switzerland: World Health Organization. 2013.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eOxborough RM, N'Guessan R, Jones R, Kitau J, Ngufor C, Malone D, et al. The activity of the pyrrole insecticide chlorfenapyr in mosquito bioassay: towards a more rational testing and screening of non-neurotoxic insecticides for malaria vector control. Malar J. 2015;14:124; doi: \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1186/s12936-015-0639-x\u003c/span\u003e\u003cspan address=\"10.1186/s12936-015-0639-x\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://www.ncbi.nlm.nih.gov/pubmed/25879231\u003c/span\u003e\u003cspan address=\"https://www.ncbi.nlm.nih.gov/pubmed/25879231\" targettype=\"URL\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eNgufor C, Agbevo A, Fagbohoun J, Fongnikin A, Rowland M. Efficacy of Royal Guard, a new alpha-cypermethrin and pyriproxyfen treated mosquito net, against pyrethroid-resistant malaria vectors. Scientific Reports. 2020;10 1:12227; doi: \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1038/s41598-020-69109-5\u003c/span\u003e\u003cspan address=\"10.1038/s41598-020-69109-5\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e. https://doi.org/10.1038/s41598-020-69109-5.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eNgufor C, N'Guessan R, Fagbohoun J, Todjinou D, Odjo A, Malone D, et al. Efficacy of the Olyset Duo net against insecticide-resistant mosquito vectors of malaria. Sci Transl Med. 2016;8 356:356ra121; doi: \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1126/scitranslmed.aad3270\u003c/span\u003e\u003cspan address=\"10.1126/scitranslmed.aad3270\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://www.ncbi.nlm.nih.gov/pubmed/27629488\u003c/span\u003e\u003cspan address=\"https://www.ncbi.nlm.nih.gov/pubmed/27629488\" targettype=\"URL\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eAccrombessi M, Cook J, Ngufor C, Sovi A, Dangbenon E, Yovogan B, et al. Assessing the efficacy of two dual-active ingredients long-lasting insecticidal nets for the control of malaria transmitted by pyrethroid-resistant vectors in Benin: study protocol for a three-arm, single-blinded, parallel, cluster-randomized controlled trial. BMC Infect Dis. 2021;21 1:194; doi: \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1186/s12879-021-05879-1\u003c/span\u003e\u003cspan address=\"10.1186/s12879-021-05879-1\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://www.ncbi.nlm.nih.gov/pubmed/33607958\u003c/span\u003e\u003cspan address=\"https://www.ncbi.nlm.nih.gov/pubmed/33607958\" targettype=\"URL\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eNgufor C, Fongnikin A, Fagbohoun J, Agbevo A, Syme T, Ahoga J, et al. Evaluating the attrition, fabric integrity and insecticidal durability of two dual active ingredient nets (Interceptor\u0026reg; G2 and Royal\u0026reg; Guard): methodology for a prospective study embedded in a cluster randomized controlled trial in Benin. Malaria Journal. 2023;22 1:276; doi: \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1186/s12936-023-04708-x\u003c/span\u003e\u003cspan address=\"10.1186/s12936-023-04708-x\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e. https://doi.org/10.1186/s12936-023-04708-x.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eAccrombessi M, Akogbeto MC, Dangbenon E, Akpovi H, Sovi A, Yovogan B, et al. Malaria Burden and Associated Risk Factors in an Area of Pyrethroid-Resistant Vectors in Southern Benin. Am J Trop Med Hyg. 2022;107 3:681\u0026ndash;8; doi: \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.4269/ajtmh.22-0190\u003c/span\u003e\u003cspan address=\"10.4269/ajtmh.22-0190\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eYovogan B, Sovi A, Padonou GG, Adoha CJ, Akinro B, Chitou S, et al. Pre-intervention characteristics of the mosquito species in Benin in preparation for a randomized controlled trial assessing the efficacy of dual active-ingredient long-lasting insecticidal nets for controlling insecticide-resistant malaria vectors. PLoS One. 2021;16 5:e0251742; doi: \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1371/journal.pone.0251742\u003c/span\u003e\u003cspan address=\"10.1371/journal.pone.0251742\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://www.ncbi.nlm.nih.gov/pubmed/34014982\u003c/span\u003e\u003cspan address=\"https://www.ncbi.nlm.nih.gov/pubmed/34014982\" targettype=\"URL\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eMutunga JM, Anderson TD, Craft DT, Gross AD, Swale DR, Tong F, et al. Carbamate and pyrethroid resistance in the akron strain of Anopheles gambiae. Pestic Biochem Physiol. 2015;121:116\u0026ndash;21; doi: \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1016/j.pestbp.2015.03.001\u003c/span\u003e\u003cspan address=\"10.1016/j.pestbp.2015.03.001\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eMyers A, Fagbohoun J, Houetohossou G, Ndombidje B, Govoetchan R, Todjinou D, et al. Identifying suitable methods for evaluating the sterilizing effects of pyriproxyfen on adult malaria vectors: a comparison of the oviposition and ovary dissection methods. Malaria Journal. 2024;23 1:164; doi: \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1186/s12936-024-04983-2\u003c/span\u003e\u003cspan address=\"10.1186/s12936-024-04983-2\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e. https://doi.org/10.1186/s12936-024-04983-2.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eCHRISTOPHERS SR. The development of the egg follicle in anophelines. Paludism. 1911;2:73\u0026ndash;88.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eSyme T, N\u0026rsquo;dombidj\u0026eacute; B, Gbegbo M, Todjinou D, Ariori V, De Vos P, et al. PermaNet Dual, a new deltamethrin-chlorfenapyr mixture net, shows improved efficacy against pyrethroid-resistant Anopheles gambiae sensu lato in southern Benin. Scientific Reports. 2023;13 1:12232; doi: \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1038/s41598-023-39140-3\u003c/span\u003e\u003cspan address=\"10.1038/s41598-023-39140-3\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e. https://doi.org/10.1038/s41598-023-39140-3.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eKim S, Piccinini D, Mensah E, Lynch M. Using a Human-Centered Design Approach to Determine Consumer Preferences for Long-Lasting Insecticidal Nets in Ghana. Glob Health Sci Pract. 2019;7 2:160\u0026ndash;70; doi: \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.9745/ghsp-d-18-00284\u003c/span\u003e\u003cspan address=\"10.9745/ghsp-d-18-00284\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eGnanguenon V, Azondekon R, Oke-Agbo F, Beach R, Akogbeto M. Durability assessment results suggest a serviceable life of two, rather than three, years for the current long-lasting insecticidal (mosquito) net (LLIN) intervention in Benin. BMC Infectious Diseases. 2014;14 1:69; doi: \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1186/1471-2334-14-69\u003c/span\u003e\u003cspan address=\"10.1186/1471-2334-14-69\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e. https://doi.org/10.1186/1471-2334-14-69.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eAhogni I, A\u0026iuml;kpon R, Oss\u0026egrave; R, Dagnon J, Govoetchan R, Attolou R, et al. Field durability of Yorkool\u0026reg; LN nets in the Benin Republic. Advances in Entomology. 2019;8 01:72\u0026ndash;92.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eKoenker H, Yukich JO. Effect of user preferences on ITN use: a review of literature and data. Malaria Journal. 2017;16 1:233; doi: \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1186/s12936-017-1879-8\u003c/span\u003e\u003cspan address=\"10.1186/s12936-017-1879-8\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e. https://doi.org/10.1186/s12936-017-1879-8.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eLukole E, Cook J, Mosha JF, Messenger LA, Rowland M, Kleinschmidt I, et al. Protective efficacy of holed and aging PBO-pyrethroid synergist-treated nets on malaria infection prevalence in north-western Tanzania. PLOS Glob Public Health. 2022;2 10:e0000453; doi: \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1371/journal.pgph.0000453\u003c/span\u003e\u003cspan address=\"10.1371/journal.pgph.0000453\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eGichuki PM, Kamau L, Njagi K, Karoki S, Muigai N, Matoke-Muhia D, et al. Bioefficacy and durability of Olyset(\u0026reg;) Plus, a permethrin and piperonyl butoxide-treated insecticidal net in a 3-year long trial in Kenya. Infect Dis Poverty. 2021;10 1:135; doi: \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1186/s40249-021-00916-2\u003c/span\u003e\u003cspan address=\"10.1186/s40249-021-00916-2\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eRaharinjatovo J, Dabir\u0026eacute; RK, Esch K, Soma DD, Hien A, Camara T, et al. Physical and insecticidal durability of Interceptor(\u0026reg;), Interceptor(\u0026reg;) G2, and PermaNet(\u0026reg;) 3.0 insecticide-treated nets in Burkina Faso: results of durability monitoring in three sites from 2019 to 2022. Malar J. 2024;23 1:173; doi: \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1186/s12936-024-04989-w\u003c/span\u003e\u003cspan address=\"10.1186/s12936-024-04989-w\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eAccrombessi M, Cook J, Dangbenon E, Sovi A, Yovogan B, Assongba L, et al. Effectiveness of pyriproxyfen-pyrethroid and chlorfenapyr-pyrethroid long-lasting insecticidal nets (LLINs) compared with pyrethroid-only LLINs for malaria control in the third year post-distribution: a secondary analysis of a cluster-randomised controlled trial in Benin. Lancet Infect Dis. 2024; doi: \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1016/S1473-3099(24)00002-1\u003c/span\u003e\u003cspan address=\"10.1016/S1473-3099(24)00002-1\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://www.ncbi.nlm.nih.gov/pubmed/38401551\u003c/span\u003e\u003cspan address=\"https://www.ncbi.nlm.nih.gov/pubmed/38401551\" targettype=\"URL\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":false,"highlight":"","institution":"","isAcceptedByJournal":true,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"parasites-and-vectors","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"parv","sideBox":"Learn more about [Parasites \u0026 Vectors](http://parasitesandvectors.biomedcentral.com/)","snPcode":"13071","submissionUrl":"https://submission.nature.com/new-submission/13071/3","title":"Parasites \u0026 Vectors","twitterHandle":"@bugbittentweets","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"em","reportingPortfolio":"BMC/SO AJ","inReviewEnabled":true,"inReviewRevisionsEnabled":true},"keywords":"Durability, attrition, fabric integrity, bioefficacy, Insecticide Treated Net, pyriproxyfen, chlorfenapyr, alpha-cypermethrin, dual active ingredients, Interceptor®, Interceptor® G2, Royal Guard®","lastPublishedDoi":"10.21203/rs.3.rs-4782261/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-4782261/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003ch2\u003eBackground:\u003c/h2\u003e \u003cp\u003eStudies evaluating the physical and insecticidal durability of dual active ingredient (AI) insecticide-treated nets (ITNs) are essential for making programmatic decisions for their deployment. We performed a prospective study embedded in a cluster randomised controlled trial (cRCT) to evaluate the attrition, fabric integrity, and insecticidal durability of Interceptor\u0026reg; G2 (alpha-cypermethrin-chlorfenapyr) and Royal Guard\u0026reg; (alphacypermethrin-pyriproxyfen), compared to Interceptor\u0026reg; (alpha-cypermethrin) in Benin.\u003c/p\u003e\u003ch2\u003eMethods\u003c/h2\u003e \u003cp\u003eA total of 2,428 study nets in 1,093 randomly selected households in 5 clusters per arm of cRCT were monitored for ITN attrition and fabric integrity every 6\u0026ndash;12 months post-distribution. Householders were further surveyed to investigate non-study net use and their preference for ITN fabric types used in the study nets. A second cohort 120 nets per ITN type withdrawn every 12 months were assessed for chemical content and insecticidal activity in laboratory bioassays. Alpha-cypermethrin bioefficacy was investigated in WHO cone bioassays and tunnel tests using susceptible \u003cem\u003eAnopheles gambiae\u003c/em\u003e Kisumu while chlorfenapyr and pyriproxyfen bioefficacy were investigated using the pyrethroid resistant \u003cem\u003eAn coluzzii\u003c/em\u003e Akron strain. Chlorfenapyr bioefficacy was assessed in tunnel tests while pyriproxyfen activity was assessed in cone bioassays as the reduction in fertility of blood-fed survivors using ovary dissection. Bioefficacy was expressed as the proportion of ITNs passing predetermined criteria i.e knock-down \u0026ge;\u0026thinsp;95% or 24hrs mortality\u0026thinsp;\u0026ge;\u0026thinsp;80% or reduction in fertility\u0026thinsp;\u0026ge;\u0026thinsp;50%.\u003c/p\u003e\u003ch2\u003eResults\u003c/h2\u003e \u003cp\u003eOverall ITN survivorship was 52% at 24 months and reduced to 15% at 36 months. Median ITN survival time was lower with Royal Guard\u0026reg; relative to Interceptor\u0026reg; (1.6 years \u003cem\u003evs\u003c/em\u003e. 2.3 years HR\u0026thinsp;=\u0026thinsp;1.49, 95% CI\u0026thinsp;=\u0026thinsp;1.36\u0026ndash;1.66, p\u0026thinsp;\u0026lt;\u0026thinsp;0.001) and Interceptor\u0026reg; G2 (1.6 years \u003cem\u003evs\u003c/em\u003e 2.1 years; HR\u0026thinsp;=\u0026thinsp;1.33, 95% CI\u0026thinsp;=\u0026thinsp;1.20\u0026ndash;1.47, p\u0026thinsp;\u0026lt;\u0026thinsp;0.001). Householders overwhelmingly preferred polyester nets relative to polyethylene nets (96%) and more Royal Guard\u0026reg; nets were replaced with spare polyester nets from previous campaigns. All Royal Guard\u0026reg; nets passed efficacy criteria for alphacypermethrin at all time points (100%) while ITN pass rates after 24 months had reduced to \u0026lt;\u0026thinsp;40% for pyriproxyfen and chlorfenapyr. The chemical content analysis showed a higher loss rate of the non-pyrethroid insecticides relative to the pyrethroids in each dual AI ITN; 74% vs 47% for Royal Guard\u0026reg; and 85% vs 63% for Interceptor\u0026reg; G2 at 36 months.\u003c/p\u003e\u003ch2\u003eConclusion\u003c/h2\u003e \u003cp\u003eThe median ITN survival time for Interceptor\u0026reg; G2 (2.1 years) and Royal Guard\u0026reg; (1.6 years) in Benin is substantially lower than the 3 years. Royal Guard\u0026reg; nets were discarded more quickly by householders partly due to their low preference for polyethylene nets. The insecticidal activity of the non-pyrethroid insecticides in both dual AI ITNs was short-lived compared to alpha-cypermethrin. The results corroborate the findings from the cRCT in Benin.\u003c/p\u003e","manuscriptTitle":"The physical and insecticidal durability of two dual active ingredient nets (Interceptor® G2 and Royal Guard®) in Benin, West Africa; results for a durability study embedded in a cluster randomised controlled trial","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2024-08-09 17:40:08","doi":"10.21203/rs.3.rs-4782261/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"decision","content":"Revision requested","date":"2024-08-28T12:10:22+00:00","index":"","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2024-08-21T14:08:54+00:00","index":"hide","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2024-08-20T22:06:02+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"208881142168276959152267985549977822029","date":"2024-08-04T23:13:39+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"253887755221172261970437889851563743095","date":"2024-08-01T13:03:12+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"271477994941376610267677028360754475892","date":"2024-07-31T19:55:56+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"253584608036679995506980968766613612041","date":"2024-07-31T15:55:37+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"226477226786503447422957959377549139441","date":"2024-07-31T07:53:29+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"94239529884639528937892778107132922276","date":"2024-07-31T01:36:12+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"67657894783700158034404214289964464270","date":"2024-07-30T18:01:10+00:00","index":"hide","fulltext":""},{"type":"reviewersInvited","content":"","date":"2024-07-30T17:58:49+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2024-07-24T08:09:25+00:00","index":"","fulltext":""},{"type":"checksComplete","content":"","date":"2024-07-24T08:01:54+00:00","index":"","fulltext":""},{"type":"submitted","content":"Parasites \u0026 Vectors","date":"2024-07-22T13:32:44+00:00","index":"","fulltext":""}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"parasites-and-vectors","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"parv","sideBox":"Learn more about [Parasites \u0026 Vectors](http://parasitesandvectors.biomedcentral.com/)","snPcode":"13071","submissionUrl":"https://submission.nature.com/new-submission/13071/3","title":"Parasites \u0026 Vectors","twitterHandle":"@bugbittentweets","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"em","reportingPortfolio":"BMC/SO AJ","inReviewEnabled":true,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"5a2d6eda-d622-48b3-8b3e-a69ec4116274","owner":[],"postedDate":"August 9th, 2024","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"published-in-journal","subjectAreas":[],"tags":[],"updatedAt":"2024-10-14T16:07:47+00:00","versionOfRecord":{"articleIdentity":"rs-4782261","link":"https://doi.org/10.1186/s13071-024-06504-1","journal":{"identity":"parasites-and-vectors","isVorOnly":false,"title":"Parasites \u0026 Vectors"},"publishedOn":"2024-10-07 15:57:31","publishedOnDateReadable":"October 7th, 2024"},"versionCreatedAt":"2024-08-09 17:40:08","video":"","vorDoi":"10.1186/s13071-024-06504-1","vorDoiUrl":"https://doi.org/10.1186/s13071-024-06504-1","workflowStages":[]},"version":"v1","identity":"rs-4782261","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-4782261","identity":"rs-4782261","version":["v1"]},"buildId":"qtupq5eGEP_6zYnWcrvyt","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}