Abstract
Background: Female genital schistosomiasis (FGS) is a chronic gynaecological disease
caused by the deposition of Schistosoma haematobium eggs in the female genital tract. It is
highly prevalent in sub-Saharan Africa (SSA), the region with the highest cervical cancer
incidence and mortality rates globally. Persistent infection with high risk (HR-) human
papilloma virus (HPV) is necessary for cervical cancer development. We aimed to determine
the cross-sectional association between FGS and HR-HPV genotypes in women across three
communities in Zambia.
Methods
Women aged 15-50, sexually active, not menstruating or pregnant, were recruited
at home by community health workers. Participants provided two cervicovaginal self-swabs,
a urine sample, collected HIV and Trichomonas vaginalis self-tests and completed a
questionnaire. At clinic follow-up, midwives collected two cervicovaginal swabs and
cervical images with point-of-care colposcopy (EVA System, MobileODT /i1). Swabs were
analysed for 14 HR-HPV types (GeneXpert /i1) and for Schistosoma DNA (ITS-2 qPCR).
Urine samples were analysed for Schistosoma ova by microscopy and for circulating anodic
antigen (CAA) to detect active infection. Visual FGS was defined as colposcopic
identification of specific genital lesions. Molecular FGS was defined as Schistosoma qPCR
positivecervicovaginal swabs.
Results
A total of 2,532 women (median age 28 years [IQR:22-36]) were recruited at home
and 67% (1,694/2,532) completed clinic follow-up. Prevalence of visual FGS, molecular
FGS, and HR-HPV were 35.2% [595/1,691], 6.5% [165/2,532], and 28.7% [690/2,401],
respectively. HIV seropositivity was 17.5% (443/2,530), with 91.2% (406/443) self-reporting
the use of antiretroviral therapy (ART). Risk factors crudely associated with HR-HPV
infection included younger age, marital status, higher number of pregnancies, molecular FGS
positivity, and urinary S. haematobium positivity detected using microscopy. There was
evidence of a weak association between molecular FGS and all HR-HPV (adjusted Odds
Ratio [aOR]=1.3, 95% Confidence Intervals [CI] 0.9-1.9). Women with molecular FGS were
significantly more likely to test positive for HR-HPV 16/18/45 (aOR=1.7, 95%CI 1.0-2.8).
No significant association was observed between visual FGS and HR-HPV infection (crude
[c] OR = 0.9, 95% CI 0.7-1.1).
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Lamberti et al. FGS and HR-HPV
3
Conclusions
To our knowledge, this is the first study to jointly screen for FGS and HR-HPV
in Zambia and to report an association between the most oncogenic HR-HPV types and
molecular FGS. These findings call for the need for integrating FGS and HR-HPV screening
strategies to address the dual burden in SSA.
Keywords
High-risk human papillomavirus, female genital schistosomiasis, cervical cancer,
Zambia, Neglected tropical diseases, sub-Saharan Africa, sexual and reproductive health
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Introduction
Female genital schistosomiasis (FGS) is a chronic and neglected gynaecological disease
estimated to affect 30-56 million women globally, mostly in sub-Saharan Africa (SSA) (1,2).
It is caused by the deposition of the eggs of Schistosoma (S.) haematobium, a waterborne
trematode, in the female genital tract (1,2). The egg-deposition is a consequence of
entrapment during egg migration from the pelvic venous plexus which induces an
inflammatory response leading to the formation of granulomas, and epithelial damage
presenting as characteristic cervicovaginal mucosal lesions (1,2). Untreated, FGS is
associated with sexual dysfunction and reproductive tract morbidity, including infertility,
dyspareunia and genital symptoms mimicking sexually transmitted infections (STIs) (2).
Despite its high prevalence and clinical burden, FGS remains largely underdiagnosed and
overlooked in schistosomiasis, and sexual and reproductive health programmes (1,2).
There are currently no guidelines for FGS screening, diagnosis, treatment, or case
management, and awareness is low among communities and healthcare providers in many
endemic settings (2,3,4). Conventional diagnosis involves collecting cervicovaginal images in
clinics using a colposcope (2, 3,4). Images are then analysed by gynaecologists and
classified as suggestive of ‘visual FGS if characteristic cervicovaginal mucosal findings,
including homogeneous sandy patches, grainy sandy patches, rubbery papules, or abnormal
blood vessels are observed (5). Visual diagnosis of FGS lesions requires expensive
equipment, advanced clinical infrastructures, and specialised training, which are often not
available in S. haematobium endemic settings (2,6). In addition, concordance between expert
reviewers is poor (Cohen’s kappa statistics=0.16), highlighting the low specificity and
Limitations
of visual FGS diagnosis on cervicovaginal images (6). Molecular testing using
polymerase chain reaction (PCR) to detect S. haematobium DNA in genital swabs
(‘molecular FGS’) offers a potentially more scalable and specific diagnostic method (3,7).
Genital samples can be collected in the clinic by a health worker or self-collected at home by
an individual, potentially increasing screening coverage (3,7).
Cervical cancer incidence and mortality is highest among women in SSA (8-10). Zambia has
the third highest incidence and mortality rates of cervical cancer in the world, with 65.5 new
cases and 43.4 cancer deaths per 100,000 women per year (11). Persistent infection with one
of the 12 high-risk (HR-) human papillomavirus (HPV) types (HPV types 16, 18, 31, 33, 35,
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39, 45, 51, 52, 56, 58, and 59) is the primary cause of cervical cancer globally (12). HPV16
and 18 are responsible for 70% of all cervical cancer cases, while HPV31, 33, 45, 52, and 58
contribute to an additional 20% of cases (12,13). HR-HPV is primarily sexually transmitted,
and risk factors include early sexual debut, greater number of lifetime sexual partners, high
parity, hormonal contraceptive use, and co-infection with other STIs (14). Women living with
HIV have a two-fold increased risk of acquiring HR-HPV (15), and a six-fold increased risk
of cervical cancer, compared to women without HIV (16). The recovery of cell-mediated
immunity following initiation of antiretroviral therapy (ART) does not necessarily remove
this risk, although early initiation of ART before significant immune depletion reduces the
risk of cervical cancer (17). The chronic genital inflammation caused by S. haematobium
eggs may facilitate HR-HPV acquisition, persistence and progression to cervical precancer,
yet this association requires further investigation (2,18).
The World Health Organization (WHO) has called for the elimination of cervical cancer by
2030, with targets including vaccinating 90% of girls by age 15; screening of 70% of women
twice by age 35 and 45 with high-performance test; and treating 90% of women with cervical
precancer and cancer (19). Zambia launched its national HPV vaccination programme in
2019 and is currently transitioning from visual inspection with acetic acid (VIA) to HPV
DNA-based screening for both the general population of women and women living with HIV,
due to its higher sensitivity and specificity to detect cervical precancer (20). HPV DNA
testing can be performed on provider- or self-collected sample (20). Self-sampling for HPV
screening has comparable sensitivity and specificity to clinician-collected samples when
tested using PCR (21,22). Molecular testing for FGS could be integrated into the cervical
cancer screening programmes and delivered at home for multi-pathogen community-based
screening (7,8). Understanding the epidemiological overlap between FGS and HR-HPV
infection is essential to inform integrated screening strategies (7).
Previous studies exploring the association of FGS and HPV in SSA showed mixed results
(2,18). A study in Zimbabwe among 236 women of reproductive age (15-49 years) found
evidence of an association between FGS, defined with the composite diagnosis of visual and
molecular methods, and HR-HPV infection (age-adjusted OR=1.9, 95%CI 1.1-3.6, p-
value=0.032) (23). Similarly, another cross-sectional study among 933 women in South
Africa found strong evidence of an association between visual FGS by colposcopy and any
HR-HPV infections (detected by GP5+/6+ HPV PCR test) (adjusted [a] OR: 1.71 95%
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CI:1.14-2.56, p=0.010) (24). In contrast, a study of 302 women in Madagascar, found no
evidence of an association between visual FGS and prevalence of any HPV infection (both
high and low risk genotypes diagnosed using the E7-multiplex genotyping PCR assay)
(OR=1.0, 95%CI 0.82-1.2) (25). A recent study in Tanzania, found no differences in rates of
HR-HPV infection between women with and without Schistosoma infection, detected by
circulating anodic antigen (CAA), an indirect measure of Schistosoma infection that does not
indicate genital involvement (26).
To our knowledge no study to date has evaluated the association between FGS diagnosed
using both visual and molecular diagnostic methods and individual HR-HPV genotypes. This
study aims to determine the risk factors for HR-HPV and the association of HR-HPV
prevalence and FGS diagnosed by visual and molecular diagnostic methods, in an ongoing
longitudinal cohort in Zambia ( Zipime-Weka-Schista study).
Methods
Study design and participants
The Zipime-Weka-Schista (Do-self-testing sister!) study is a four-year longitudinal cohort
study evaluating the performance and acceptability of multi-pathogen self-sampling for
genital infections among women in Zambia, (27). This analysis uses baseline data collected
between January 2022 and April 2023, across three sites (Livingstone, Sikoshwe, and
Chanyanya). Briefly, girls and women aged from 15 to 50 years old, non-pregnant, sexually
active, and who had been resident for at least a year in one of the study sites were eligible for
enrolment. Participants were randomly selected through community-based random sampling
and enrolled at home by trained Schista Community Workers (SCWs) (27). Further details
are described in elsewhere (27).
Samples collection
During the home visit, participants received study information, provided written informed
consent, completed a questionnaire administerd by a SCW, and self-collected two
cervicovaginal swabs and a urine specimen (27). One swab was stored in PrimeStore® MTM
molecular transport media (donated by Longhorn Vaccines and Diagnostics LLC, Bethesda,
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US) for the detection of Schistosoma DNA (S1 Text) (27). The second swab was used for
HR-HPV testing and was predominantly stored in PrimeStore® MTM molecular transport
media (80% of baseline samples), with a smaller subset stored in ThinPrep Cytopreserve®
solution (S1 Text). Urine was tested on the same day at the field laboratory for S.
haematobium egg-patent infection by urinary egg microscopy (S2 Text). A 2mL urine sample
was shipped to Leiden University Medical Centre (LUMC), The Netherlands for Schistosoma
CAA detection using the up-converting reporter particle lateral flow CAA test (UCAA hT417
format, CAA-levels >0.6 pg/mL were considered positive) (S3 Text) (28). Participants were
also offered HIV ( OraQuick® HIV Self-Test) and Trichomonas (T.) vaginalis self-tests
(OSOM® Trichomonas Rapid Test). For both self-tests, results were read by the SCW and
immediately shared with the participant. HIV-positive self-test results were confirmed on-site
using a point-of-care diagnostic test (Determine
TM) (27). Participants who tested positive for
HIV or T. vaginalis at home were referred to the clinic for treatment and linkage to care.
Following the home visit, enrolled participants who were not menstruating were invited for
the clinic follow-up (27). After speculum insertion, a midwife collected two cervicovaginal
swabs, a cervicovaginal lavage (CVL), and cervicovaginal images with a point-of-care
colposcope (EVA MobileODT®, Tel Aviv, Israel), which are saved to an online portal for
remote review. Similarly to the home visit, one cervicovaginal swab was stored in
PrimeStore® MTM molecular transport (donated by Longhorn Vaccines and Diagnostics
LLC, Bethesda, US) media and the second in Cytopreserve®. A CVL specimen was obtained
by flushing 10mL of normal saline across the cervix and vaginal walls for one minute using a
bulb syringe. The fluid was then collected from the posterior fornices with a pipette and
transferred into a centrifuge tube containing PrimeStore® MTM. The CVL sample was
stored at -20
oC on site (S1 Text).
Visual FGS
Colposcopic cervicovaginal images were independently evaluated remotely by two
experienced gynaecologists (BD and DK). In the case of disagreement between the two
reviewers, a third reviewer (IH) was asked to independently analyse the images of the
discordant case. Partcipant were defined as ‘visual FGS’ positive if at least two of the
reviewers independently identified at least one of the four lesion types; homogeneous yellow
sandy patches, grainy sandy patches, rubbery papules, or abnormal blood vessels, and as
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negative if none of these lesions were observed (5). Women with evidence of
schistosomiasis, ‘molecular FGS’ and/or ‘visual FGS’ were treated with 40mg/kg
praziquantel delivered as a single dose (30).
Molecular FGS
Cervicovaginal swabs stored in Primestore® MTM were processed at Zambart central
laboratory (Lusaka, Zambia) for the detection of Schistosoma DNA using Internal-
trasncribed-spacer-2 (ITS-2) by real-time PCR (ITS qPCR) (S4 Text). Total nucleic acid
(TNA) extraction (PrimeXtract™ Longhorn Vaccines & Diagnostics, USA) was performed
as per manufacturer’s instructions, using a simplified silica-based spin column extraction
process. qPCR was performed as previously reported and results were reported in cycle
threshold values (Ct-values) and considered positive if any C
t-value was observed and
negative if no C t-value was observed (3,29). Women were classified as ‘molecular FGS’
positive if either self- or provider-collected cervicovaginal swab tested positive for
Schistosoma DNA via qPCR.
HR-HPV detection
Self-collected cervicovaginal swabs stored in either PrimeStore® Molecular Transport
Medium (MTM) or in ThinPrep Cytopreserve® were tested for HR-HPV detection using a
multiplex real-time PCR assay (GeneXpert HPV®, Cepheid, Sunnyvale, CA, USA) which
simultaneously detects 14 HR-HPV types (HPV 16, 18, 45, 31, 33, 35, 52, 58, 51, 59, 39, 56,
66, 68), grouped into three channels: HPV type 16; HPV types 18 or 45 (or both); and any
other HR-HPV types. DNA extraction for samples stored in PrimeStore® Molecular
Transport Medium (MTM) was performed using a modified PrimeXtract™ spin column
protocol (S5 Text). For GeneXpert HPVanalysis, 50 µL of the extracted DNA was diluted in
1mL of normal saline and loaded into the GeneXpert cartridge, following the standard assay
protocol. A sample adequacy control (SAC) and a Probe Check Control (PCC) was also
provided in the cartride (S5 Text). If a test result on the self-collected swab was invalid, HR-
HPV testing was done using the healthcare provider-collected swab (S6 Text).
HR-HPV definitions
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Participants were classified as HR-HPV positive if positive for at least one of the 14 HR-
HPV types (HPV 16, 18, 45, 31, 33, 35,52,58,51,39, 56, 66, 68); HPV16/18/45 positive if
positive for the HPV type 16, and/or the HPV type 18 and/or 45 channels; and HPV16
positive if only the HPV type 16 channel was positive (S1 Figure). Samples were classified as
invalid if both the home-based self-collected swab and clinic-based provider-collected swab
returned invalid results (S6 Text). This classification allowed to distinguish HPV16 and
HPV18 and HPV45 from the other HR-HPV genotypes as they are the most oncogenic
genotypes (12,13). HR-HPV positive women were referred to a gynaecologist for colposcopy
and a two-quadrant cervical biopsy according to age and HIV status (27). All women with
cervical precancer were referred for management as per national guidelines (20).
Statistical analyses
Data were entered on hand-held electronic devices using Open Data Kit (ODK) and analysed
using Stata 17.0 (StataCorp, LP, College Station, US). Primary outcomes were detection of
any HR-HPV, HPV type 16 or 18 and/or 45 (HPV16/18/45) and HPV type 16 only. The
HPV16/18/45 outcome was defined by combining outputs from the HPV type 16, and the
HPV type 18 and/or 45 channels. The denominator throughout this analysis was all women
with valid HPV DNA test results. Descriptive statistics were used to summarise participants’
characteristics, stratified by HR-HPV status. Univariable logistic regression analyses were
used to estimate crude odds ratios (cOR) and 95% confidence intervals (CI) for the
associations between HR-HPV and potential risk factors. Potential risk factors were informed
by the published literature. Multivariable logistic regression models were used to estimate
adjusted odds ratios (aOR) and 95% CI for the associations between HR-HPV and factors
associated with HR-HPV in univariable analysis. (p-value<0.05). Covariates with missing
data or those applicable only to a subgroup were excluded. Multicollinearity was assessed
between variables in the final models.
Ethical considerations
The study was approved by the University of Zambia Biomedical Research Ethics Committee
(UNZABREC) (reference: 1858-2021), the National Health Research Authority (NHRA)
(Reference: 00012/24/09/2021), and the London School of Hygiene and Tropical Medicine
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(LSHTM) (reference: 25258). Ministry of Health and local superintendents approved the
study in September 2021.
Results
Figure 1 shows the study flow. At baseline, 2,532 women (median age: 28 years, interquartile
range [IQR] 22-36) were enrolled at home, and 67% (1,694/2,532) completed the clinic
follow-up after a median of two days (IQR: 1-11 days). Cervicovaginal swabs and urine
samples were collected from all women at enrolment. All urine samples were tested for S.
haematobium ova detection by microscopy, and 99.4% (2,517/2,532) were tested for
presence of CAA. Visual FGS status was available for 99.8% (1,691/1,694) of participants
who completed the clinic follow-up. HR-HPV DNA testing was performed on 98.3%
(2,488/2,532) of participants, and 96.5% (2,401/2,488) gave a valid HR-HPV result.
Molecular FGS diagnosis was available for all study participants (Figure 1). Data for both
HR-HPV and molecular FGS status were available for 94.8% (2,401/2,532) of participants,
and for HR-HPV and visual FGS in 96.7% (1,639/1,694) of clinic attendees.
Participant characteristics
Of 2,532 women, 165 (6.5%) tested positive for molecular FGS (median Ct-value= 35.1,
IQR:7.4-31.6) (Table 1). Visual FGS was identified in 35.2% (595/1,691) of participants,
(Table 1). Egg-patent S. haematobium infection was detected in 5.2% (132/2,532) of
participants (mean intensity: 4.8 eggs/10mL of urine; Standard deviation [SD]: 5.5).
Schistosoma CAA positivity was observerd in 15.4% (388/2,517) (median CAA
concentration=4.6 pg/mL; IQR 1.1-31.0) (Table 1). HIV prevalence was 17.5% (443/2,532),
with 91.6% (406/443) of self-reporting antiretroviral therapy (ART) use (Table 1). The
prevalence of T. vaginalis by rapid diagnostic test (RDT) was 10.3% (246/2,389) (Table 1).
Distribution of infection by age
The distribution of molecular FGS, visual FGS and HR-HPV infection by age is shown in
Figure 2 (S1 Table). The prevalence of molecular FGS was highest among adolescents aged
15-19 years (14.6%) and declined with age ( χ ² < 0.00) (Figure 2, S1 Table). In contrast,
prevalence of visual FGS increased with age, peaking among women aged 46-50 years
(53.4%) χ ² < 0.001) (Figure 2, S1 Table). HR-HPV prevalence declined significantly with age
(p-value<0.001). Compared to women aged 46-50 years, girls and women aged 15-25 years
old had higher risk of HR-HPV (15-19 years vs. 46-50 years; 36.0% vs. 20.6%; cOR =2.2,
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95%CI 1.3-3.5; 20-25 years vs. 46-50 years: 35.1% cOR=2.1, 95% CI 1.3-3.3) (Figure 2 and
Table 1).
Prevalence and risk factor analysis for prevalence of any HR-HPV
Prevalence of any HR-HPV genotypes was 28.7% (690/2,401) (Table 1). HR-HPV
prevalence declined significantly with age (p-value<0.001). Any HR-HPV prevalence was
higher among women with molecular FGS compared to those without (36.1% vs. 28.2%;
cOR= 1.5, 95%CI 1.0-2.0) (Table 1). No statistically significant difference was observed by
visual FGS status (visual FGS positive vs. negative 28.0% vs. 31.2%, cOR=0.9, 95%CI 0.7-
1.1), either overall or by lesion type (Table 1 and S2 Table). Women with urinary S.
haematobium by microscopy had a higher prevalence of any HR-HPV compared to those
without (40.2% vs. 28.1, cOR=1.7, 95%CI 1.2-2.5). However, this association was not
observed with Schistosoma infection by CAA (cOR=1.0, 95%CI 0.8-1.3) (Table 1). No
significant differences in HR-HPV prevalence were observed by HIV status (cOR=1.0,
95%CI 0.8-1.2) or T. vaginalis status (cOR= 1.2, 95%CI 0.9-1.6) (Table 1). After adjusting
for age, marital status, and number of pregnancies molecular FGS was not significantly
associated with any HR-HPV prevalence (aOR=1.3, 95% CI=0.9-1.9) (Figure 3). Women
aged 20-25 years had higher odds of HR-HPV infection compared to women aged >= 45
years (aOR=1.65, 95%CI 1.1-2.5). Married women had lower odds of HR-HPV infection
compared to single women (aOR=0.6, 95%CI 0.5-0.8) (Table 1, Figure 3. Due to
multicollinearity between ‘molecular FGS’ and urinary S. haematobium infection (r=0.56), a
separate model evaluated the association between urinary S. haematobium infection by
microscopy and infection with any HR-HPV (aOR=1.7, 95%CI 1.1–2.4) (S3 Table)
Prevalence and risk factor analysis for infection with high oncogenic types; HPV16, 18 and
45
HPV 16/18/45
Prevalence of infection with any of the HPV16/18/45 was 9.6% (231/2,401) (Table 2). In
univariable analysis, higher prevalence was observed among HIV-positive versus HIV-
negative women (12.5% [53/424] vs. 8.9% [166/1,864], cOR=1.5, 95%CI 1.1-2.0), and
among women with T. vaginalis compared to those without (14.6% [35/240] vs. 8.8%
[177/2,019], cOR=1.8, 95%CI 1.2-2.6) (Table 2). HPV16/18/45 prevalence was higher
among women with molecular FGS compared to those without (15.8% [25/158] vs. 9.2%
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[206/2,243], cOR=1.9, 95%CI 1.2-2.9), but no association was observed with visual FGS
(cOR=0.8, 95%CI 0.6-1.2) (Table 2, S4 Table). In adjusted analysis, molecular FGS
(aOR=1.7, 95%CI 1.0-2.8), HIV status (aOR=1.7, 95%CI 1.2-2.4), and T. vaginalis status
(aOR=1.5, 95%CI 1.0-2.2) were associated with increased odds of HPV16/18/45 infection
(Figure 4).In addition, single women had higher odds of HPV16/18/45 infection compared to
married women, (aOR=1.9, 95%1.4-2.9), and participants residing in Chanyanya were more
likely to be infected than those from Shikoswe (aOR=3.6, 95%CI 1.4-9.3) (Figure 4).
HPV16 only
HPV16 prevalence was 4.8% (114/2,401) (Table 3). HPV16 prevalence was higher among
single women compared to married women (6.6% [58/886] vs. 3.5% [46/1,329], cOR=2.0,
95%CI 1.3-2.9) (Table 3). Women with molecular FGS had higher HPV16 prevalence
compared to those without (8.2% [13/158] vs. 4.5% [101/2,243]; cOR=1.9, 95%CI 1.0-3.5)
(Table 3). No significant association was observed with visual FGS status (cOR=0.8, 95%CI
0.5-1.2), urinary S. haematobium status by microscopy (cOR=1.4, 95%CI 0.7-2.9),
Schistosoma status by CAA (cOR=1.2, 95%CI 0.8-2.0), HIV status (cOR=1.4, 95%CI 0.9-
2.2), or T. vaginalis status (cOR=1.4, 95%CI 0.8-2.5) (Table 3, S5 Table). After adjusting for
marital status and parity, women with molecular FGS had 1.8 higher odds of being HPV16
positive compared to those without (aOR=1.8, 95%CI 1.0-3.4) (Figure 5).
Discussion
To our knowledge, the Zipime-Weka-Schista study is the first to investigate the association
between HR-HPV and FGS, diagnosed using both visual and molecular methods, in a large
cohort of women with and without HIV in Zambia (27). We found a significant association
between women with FGS defined as DNA detected by qPCR from cervicovaginal swabs
(molecular FGS) and HPV16/18/45, the most frequently associated with cervical precancer
and cancer. In contrast, no significant association was found between visual FGS, diagnosed
using colposcopy, and HR-HPV infection. These findings highlight the need to recognize
FGS as a sexual and reproductive health (SRH) condition and to integrate FGS screening into
cervical cancer control programmes to improve early detection and reduce the dual burden of
diseases in S. haematobium endemic settings (7).
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13
Women with molecular FGS were almost 1.7 times more likely to test positive for
HPV16/18/45, the most oncogenic genotypes which contribute to the majority of cervical
precancer and cancer globally (12,13). To our knowledge, this is the first study to compare
molecular FGS with molecular detected HR-HPV infection from cervicovaginal self-swabs
for both infections. This finding suggests that FGS may play a role in the natural history of
cervical HPV infection. HPV infects the undifferentiated, proliferating basal cells of the
cervicovaginal epithelium through microabrasion, often resulting from co-existence of other
STIs or co-factors that compromise the epithelial barrier (31). The epithelial damage of the
anogenital mucosa caused by S. haematobium egg deposition in women with FGS may
facilitate HPV viral entry (18). Further, the chronic genital inflammation caused by the S.
haematobium egg deposition in the female genital tract may impair local immune responses,
promoting immune evasion and HR-HPV persistence (18,31). Although the cross-sectional
nature of this analysis does not allow to distinguish between incident and persistent HR-HPV
infections, the observed association between molecular FGS and HPV16/18/45 support the
hypothesis that FGS may contribute to HPV persistence. This aligns with findings from a
recent study in Tanzania that followed 96 HIV-negative women and found higher odds of
HR-HPV persistence at 9-12 months among women with Schistosoma infection, diagnosed
by CAA (32). This analysis did not assess for genital involvement of schistosome infection
but it supports the hypothesis that the schistosomiasis-related inflammation may contribute to
persistence of HR-HPV infection (32). Longitudinal data from the ongoing Zipime-Weka-
Schista study will further evaluate whether FGS promotes persistence or delays clearance of
HR-HPV (27).
Women with egg-patent urinary S. haematobium infection were more likely to have prevalent
HR-HPV infection, compared to those without. In contrast, no significant association was
observed between schistosomiasis detected by CAA and HR-HPV infection. This may reflect
the differences between diagnostic method (30). CAA is a highly sensitive diagnostic method
for active Schistosoma infection, detecting antigens released by live adult worms in the host’s
bloodstream (28). However, it does not provide information on egg deposition or differentiate
between species (28). The absence of an observed association between CAA and HR-HPV
but a positive association with egg-patent urinary schistosomiasis highlights the complexity
of active infection in the pathogenesis of HR-HPV in the presence of S.haematobium.
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14
In our study, visual FGS, diagnosed by colposcopy, was not associated with HR-HPV
prevalence. Previous studies on this association reported mixed results, likely due to
differences in outcome definitions, with one study including any HPV type (both high- and
low- risk genotypes) and the other any HR-HPV type (24,25). Although colposcopy is widely
used to assess FGS-related morbidity, its scalability in S. haematobium endemic settings is
limited by high cost, infrastructure requirements, and need for trained personnel (2,6).
Importantly, the mucosal changes in visual FGS positive women can be similar to changes
from other SRH, including cervical lesions caused by HPV, resulting in limited diagnostic
specificity (6,7). In our study, agreement between two expert reviewers in detecting visual
FGS was low, consistent with previous research in Zambia (6). This reinforces the limitation
of visual diagnosis for FGS and highlights the need for standardised, scalable diagnostic
Methods
(6). Emerging technologies such as computer vision, powered by artificial
intelligence (AI), are being explored to aid in the visual diagnosis of FGS (33,34,35).
Computer vision tools are in the later stages of validation for the automated detection of
cervical precancer and cancer in colposcopy images, potentially offering a point of
integration for visual diagnosis of both FGS and cervical cancer (36).
Prevalence of HR-HPV was highest among women young women 15-25 years old, consistent
with previous studies (37-40). Across our study population, prevalence of molecular FGS
decreased with increasing age and peaked among adolescents aged 15-19 years old. In
contrast, more older women (aged 41-50 years old) were positive for visual FGS . These
findings are consistent with previous studies (3, 4, 29, 42). The similar age distribution
supports possible opportunities to integrate FGS into cervical cancer control programmes (7).
This is particularly timely as Zambia transitions from VIA to HPV DNA-based cervical
screening programmes (20). For instance, existing self-collection platform and laboratory
infrastructures for cervical cancer screening could include molecular FGS testing in endemic
districts, improving earlier detection and more efficient use of resources (7). Younger women
are more susceptible to HR-HPV infection due to behavioural and biological factors,
including early sexual debut, multiple sexual partners, low contraception use, and cervical
ectopy (37-40). In S. haematobium endemic settings, women in this age group also tend to
have higher intensity of S. haematobium infection and higher rates of Schistosoma DNA
retrieval from the genital tract, likely due to increased vascularization which promotes
inflammation and parasite DNA shedding on the mucosal surface (3,29,42). In contrast, older
women typically show higher prevalence of visually diagnosed lesions from long-standing S.
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15
haematobium egg deposition or chronic infection, reflecting the cumulative burden of FGS
over time (3,29,42). This age-specific pattern suggests that, in S. haematobium endemic
settings, molecular FGS screening could be integrated with HPV vaccination and education
programmes targetting younger girls (aged 9-14 years old), while community-based
integrated HPV and molecular FGS screening can be introduced for women of reproductive
age eligible for cervical cancer screening (age 25 or 30 depending on HIV status) (19,20). For
older women (aged over 35 years), FGS screening can be integrated into existing cervical
cancer clinic-based screening and/or treatment programmes (19,20). These targeted age-
specific efforts offer an approach for addressing the dual burden FGS and cervical cancer
vulnerable populations.
Prevalence of any HR-HPV did not vary by HIV status, differing from previous studies
showing higher HR-HPV prevalence and persistence among women living with HIV (15).
This finding may reflect the high proportion of participants on ART and younger age in our
study population. ART has been reported to reduce HPV persistence and precancer and
cancer incidence, especially when initiated early following HIV acquisition and before
significant immune suppression (17). Yet, these benefits have primarily been demostranted in
monitored cohorts where women achieve sustained viral suppression through long-term ART
adherence and regular cervical cancer screening. In our community-based study, ART status
was self-reported, and baseline data on CD4+ T-cell count and HIV plasma viral load were
not available at the time of this analysis, limiting our ability to assess immune control and its
associations with HPV infection. Of note, we observed a 1.7-fold higher prevalence of the
most oncogenic HPV types 16/18/45 among women living with HIV compared to HIV
negative women, consistent with the literature (43,44,45).
With over 2,500 women recruited in the cohort, this is the largest study to date to evaluate
the association between HR-HPV prevalence and FGS, diagnosed using both molecular and
visual methods. The integrated nature of the study design, combining home and clinic-based
sampling with multiple diagnostic methods allowed for comprehensive screening for FGS
and SRH co-infections. The feasibility of this approach is reflected in the succesful
recruitment and diagnostic completeness obtained. There are some limitations worth noting.
Histological examination of cervical tissues for the detection of Schistosoma eggs was not
performed, limiting the ability to compare molecular and visual FGS diagnoses against a
Reference
standard, as both have imperfect sensitivity and specificity (2,6,46). The reliability
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16
of visual FGS diagnosis was limited by low agreement between two expert reviewers,
highlighting the need for standardised visual diagnostic methods. Implementation of
molecular FGS testing in routine clinical or programmatic setting is hindered by cost,
technical requirements, and the need for trained personnel. Moreover, variations in assay
design may affect comparability across laboratories for PCR testing. Although this study
accounted for HIV and T. vaginalis status, it did not address potential confounding by other
STIs, including Chlamydia trachomatis, Neisseria gonorrhoea, Mycoplasma genitalium,
Herpes simplex virus, syphilis, and bacterial vaginosis, all of which can affect cervical
inflammation and epithelial integrity (47). HIV status was self-reported for most participants
which may have introduced reporting bias. Data on CD4+ T-cell count, time on ART, ART
adherence and HIV plasma viral load among the study participants was not collected,
potentially introducing further confounding. Further, the cross-sectional design of this
analysis does not allow to distinguish between incident and persistent HR-HPV infections,
limiting causal inferences on the association between FGS and HR- HPV. Longitudinal data
from the ongoing Zipime-Weka-Schista study (27) will address some of these limitations in
future analyses.
This study contributes new evidence on the intersection of FGS, HR-HPV and SRH among
women of reproductive age living, highlighting a significant association between molecular
FGS and the most oncogenic HPV genotypes (HPV16/18/45). In line with the Sustainable
Development Goals and the WHO targets to eliminate cervical cancer and schistosomiasis,
our findings support the need for integrated strategies using highly specific, field-deployable,
and cost-effective diagnostic methods.
Declaration of interest
We declare no competing interests.
Acknowledgements
We would like to thank and acknowledge all the study participants and the communities in
Kafue and Livingstone for their engagement and support. We acknowledge the invaluable
contribution of Zipime-Weka-Schista community workers, field teams and midwives. We
also thank the wider Zipime-Weka-Schista Study team who contributed towards the design
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17
and implementation of the study and Isaac Mshanga for his work on community sensitization
and mobilization. We are grateful for our partners in Zambia, including the Ministry of
Health and District Health Management Teams, as well as the administrative support teams at
both Zambart and LSHTM. We gratefully acknowledge the team at the Leiden University
Medical Centre (LUMC) for performing the CAA analysis. We thank the ODK forum for
assistance with questionnaire construction and Chrissy Roberts (LSHTM) for his invaluable
support with 3D printing of teaching models.
Funding
The Zipime-Weka-Schista study is funded through a UKRI Future Leaders Fellowship (MR/
T041900/1) awarded to Professor AL Bustinduy. Professor E Webb received funding from
MRC Grant Reference MR/K012126/1. This award is jointly funded by the UK Medical
Research Council (MRC) and the UK Department for International Development (DFID)
under the MRC/DFID Concordat agreement and is also part of the EDCTP2 programmme
supported by the European Union. Olimpia Lamberti is funded by the Nagasaki University
‘Doctoral Program for World-leading Innovative and Smart Education’ for Global Health,
KENKYU SHIDO KEIHI.
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18
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Tables and figures for the manuscript “Association between female genital 217
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in Zambia: the Schista study” 219
220
221
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Figure 1: Zipime-Weka-Schista study flow diagram for participant recruitment at baseline 224
and screening of molecular FGS, visual FGS and HR-HPV. 225
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226
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is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity.(which was not certified by peer review)preprint
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A 227
228
B 229
230
Figure2: Distribution of positive diagnostic test results by age categories. A: Distribution of 231
molecular FGS and visual FGS by age groups. B: Prevalence of any HR-HPV infection, 232
HPV16/18/45 and HPV16 only by age categories. The corresponding data is presented in 233
Table 1 and S1 Table. 234
235
236
Table 1: Prevalence of any high-risk HPV (HR-HPV) stratified by socio-demographic 237
characteristics and co-infections, with univariable logistic regression estimates across the 238
study population (N = 2,401). 239
N (%) HR-HPV Neg
N (%)
HR-HPV Pos
N (%)
Crude OR
(95%CI)
p-value
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25
Total 2,532 (100) 1,711(71.3) 690 (28.7)
Socio-demographic characteristics
Age (years)
15-19 330 (13.0) 199 (64.0) 112 (36.0) 2.2 (1.3-3.5) <0.001
20-25 674 (26.6) 412 (64.9) 223 (35.1) 2.1 (1.3-3.3)
26-30 553 (21.8) 380 (72.1) 147 (27.9) 1.5 (0.9-2.4)
31-35 341 (13.5) 245 (75.9) 78 (24.2) 1.2 (0.8-2.0)
36-40 293 (11.6) 223 (80.2) 55 (19.8) 1.0 (0.6-1.6)
41-45 200 (7.9) 144 (75.4) 47 (24.6) 1.3 (0.7-2.1)
46-50 141 (5.6) 108 (79.4) 28 (20.6) Ref
Marital status
Single 330 (13.0) 559 (63.1) 327 (36.9) 2.0 (1.6-2.4) <0.001
Married 674 (26.6) 1,023 (77.0) 306 (23.0) Ref
Divorced/separated 553 (21.8) 92 (71.9) 36 (28.1) 1.3 (0.9-2.0)
Widowed 341 (13.5) 36 (63.2) 21 (36.8) 2.0 (1.1-3.4)
Education
No schooling 49 (1.9) 36 (78.3) 10 (21.7) Ref 0.21
Some/Completed primary
school
909 (35.9)
620 (72.6) 234 (27.4) 1.4 (0.7-2.8)
Some/completed secondary
school
1,344 (53.1) 898 (70.2) 381 (29.8) 1.5 (0.8-3.1)
Some/completed trade
school or degree
229 (9.1) 156 (70.6) 65 (29.4) 1.5 (0.7-3.2)
District of residence
Shikoshwe 1,176 (46.5) 818 (72.1) 316 (27.9) Ref 0.44
Livingstone 1,196 (47.2) 781 (70.4) 328 (29.6) 1.1 (0.9-1.3)
Chanyanya 160 (6.3) 112 (70.9) 46 (29.1) 1.1 (0.7-1.5)
Sexual and Reproductive health behaviours and outcomes
Number of sexual partners in the last 6 months
0 131 (5.2) 88 (69.8) 38 (30.2) Ref 0.49
1 2,144 (84.7) 1,457 (71.7) 574 (28.3) 0.9 (0.6-1.4)
2 152 (6.0) 96 (67.1) 47 (32.9) 1.1 (0.7-1.9)
2 or more 105 (4.2) 70 (69.3) 31 (30.7) 1.0 (0.6-1.8)
Age of sexual debut
20 years old 282 (11.2) 200 (75.8) 64 (24.2) 0.7 (0.5-1.0)
Time to conception of previous pregnancy
0-3 months 401 (19.2) 277 (74.1) 97 (25.9) Ref 0.4
4-6 months 95 (4.5) 66 (69.5) 29 (30.5) 1.3 (0.8-2.1)
10-12 months 1,038 (49.6) 722 (73.7) 258 (26.3) 1.0 (0.8-1.3)
I don’t remember 31 (1.5) 24 (80.0) 6 (20.0) 0.7 (0.3-1.8)
Pregnancy was unplanned 529 (25.3) 354 (70.0) 152 (30.0) 1.2 (0.9-1.7)
Number of pregnancies
Never pregnant 437 (17.3) 267 (64.3) 148 (35.7) 1.8 (1.4-2.5) <0.001
1 pregnancy 551 (21.8) 335 (64.6) 184 (35.5) 1.8 (1.4-2.5)
2 pregnancies 431 (17.0) 289 (71.0) 118 (29.0) 1.4 (1.0-1.9)
3 pregnancies 402 (15.9) 287 (74.4) 99 (25.7) 1.1 (0.8-1.6)
4 pregnancies 289 (11.4) 227 (82.3) 49 (17.8) 0.7 (0.5-1.1)
> 4 pregnancies 422 (16.7) 306 (76.9) 92 (23.1) Ref
Type of contraception used
None 10 (0.8%) 7 (77.8) 2 (22.2) Ref 0.41
Barrier method (condom,
diaphragm or IUD)
139 (11.4%) 101 (74.8) 34 (25.2) 1.2 (0.2-5.9)
Hormonal method
(implant, injectable or oral
pill)
999 (82.1%) 697 (71.7) 275 (28.3) 1.4 (0.3-6.7)
Sterilization method 1 (0.1%) 1 Not enough data
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26
Combination (hormonal
and barrier)
69 (5.7%) 46 (68.7) 21 (31.3) 1.6 (0.3-8.4)
Number of stillbirths
None 1,978 (94.5) 1,360 (72.6) 513 (27.4) Ref 0.006
One or more 116 (5.5) 351 (66.5) 177 (33.5) 1.3 (1.1-1.6)
Co-infections
HIV status
Negative 1,970 (77.8) 1,330 (71.4 ) 534 (28.7) Ref 0.74
Positive 443 (17.5) 304 (71.7) 120 (28.3) 1.0 (0.8-1.2)
Unknown 119 (4.7) 77 (68.1) 36 (31.9) 1.2 (0.8-1.8)
Self-reported antiretroviral therapy (ART) use among HIV-positive (Ntot=443)
No 38 (8.6) 20 (54.1) 17 (45.7) 2.3 (1.2-2.4) 0.02
Yes 405 (91.4) 284 (73.4) 103 (26.6) Ref
Trichomonas vaginalis status
Negative 2,143 (89.7) 1,444 (71.5) 575 (28.5) Ref 0.15
Positive 246 (10.3) 161 (67.1) 79 (32.9) 1.2 (0.9-1.6)
Molecular FGS1
Negative 2,366 (93.5) 1,610 (71.8) 633 (28.2) Ref 0.04
Positive 165 (6.5) 101 (63.9) 57 (36.1) 1.5 (1.0-2.0)
Median Ct (IQR) 35.1 (7.4-31.6) 35.7 (31.3-39.0) 35.1 (31.8-38.7)
Visual FGS by colposcopy2
Negative 1,096 (64.8) 729 (68.8) 331 (31.2) Ref 0.17
Positive 595 (35.2) 417 (72.0) 162 (28.0) 0.9 (0.7-1.1)
Schistosoma infection by Circulating Anodic Antigen (CAA)
Negative 2,129 (84.6) 1,437 (71.2) 580 (28.8) Ref 0.99
Positive 388 (15.4) 263 (71.3) 106 (28.7) 1.0 (0.8-1.3)
Median pg/mL3 (IQR) 4.6 (1.1-30.6) 3.4 (1.0-26.7) 10.2 (1.2-50.3)
S. haematobium by microscopy
Negative 2,400 (94.8) 1,635 (71.9) 639 (28.1) Ref 0.004
Positive 132 (5.2) 76 (59.8) 51 (40.2) 1.7 (1.2-2.5)
Mean egg-count (SD) per
10mL3
4.8 (5.5) 4.9 (4.8) 4.8 (6.7)
Percentages (%) in the first column are based on the total number of observations (N=2,532).
Percentages (%) on the second and third columns are calculated within each row total.
1Molecular FGS refers to PCR diagnosis of either home-based self-collected cervicovaginal swabs or clinic-based
provider-collected cervicovaginal swabs.
2 Visual FGS defined as a positive if confirmed by both reviewers 1 and 2, or in case of disagreement, by reviewer 3. The association
between the single visual FGS and HR-HPV infection are presented in S2 Table
3Mean egg count, CAA concentrations and PCR Ct-values are restricted to positive tests.
Abbreviations: AOR = Adjusted Odds Ratio, CI = Confidence Interval
240
241
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242
The regression model was adjusted for molecular FGS status, age, marital status and number of pregnancies. 243
Abbreviations: aOR= Adjusted odds ratios. 244
245
Figure 3: Multivariable logistic regression model parameter estimates with prevalence of any 246
HR-HPV as the dependent variable across the study population (N=2,401). 247
248
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28
249
Table 2: Prevalence of HPV16/18/45 stratified by socio-demographic characteristics and co-250
infections, with univariable logistic regression estimates across the study population (N = 251
2,401). 252
HPV16/18/45 Neg N
(%)
HPV16/18/45 Pos N
(%)
Crude OR
(95%CI)
p-value
Total 2,170 (90.4) 231 (9.6)
Socio-demographic characteristics
Age (years)
15-19 279 (89.7) 32 (10.3) 2.1 (0.91-4.9) 0.09
20-25 569 (89.6) 66 (10.4) 2.1 (1.0-4.8)
26-30 472 (89.6) 55 (10.4) 2.1 (1.0-4.8)
31-35 291 (90.1) 32 (9.9) 2.0 (0.9-4.7)
36-40 260 (93.5) 18 (6.5) 1.3 (0.5-3.1)
41-45 170 (89.0) 21 (11.0) 2.3 (0.9-5.1)
46-50 129 (94.9) 7 (5.2) Ref
Marital status
Single 770 (86.9) 116 (13.1) 1.9 (1.5-2.6) 0.001
Married 1,233 (92.8) 96 (7.2) Ref
Divorced/
separated
113 (88.3) 15 (11.7) 1.7 (1.0-3.0)
Widowed 53 (93.0) 4 (7.0) 1.0 (0.3-2.7)
Education
No schooling 44 (95.7) 2 (4.4) Ref 0.87
Some/Completed primary
school
769 (90.1) 85 (9.9) 2.4 (0.6-10.2)
Some/completed secondary
school
1,157 (90.5) 122 (9.5) 2.3 (0.6-9.7)
Some/completed trade school
or degree
199 (90.1) 22 (10.0) 2.4 (0.6-10.7)
District of residence
Shikoshwe 1,047 (92.3) 87 (7.7) Ref <0.001
Livingstone 990 (89.3) 119 (10.7) 1.4 (1.1-1.9)
Chanyanya 133 (84.2) 25 (15.8) 2.3 (1.4-3.7)
Sexual and Reproductive health behaviours and outcomes
Number of sexual partners in the last 6 months
0 115 (91.3%) 11 (8.7%) Ref 0.60
1 1,836 (90.4%) 195 (9.6%) 1.1 (0.6-2.1)
2 129 (90.2%) 14 (9.8%) 1.1 (0.5-2.6)
More than 2 90 (89.1%) 11 (10.9%) 1.3 (0.5-3.0)
Age of sexual debut
20 years old 239 (90.5%) 25 (9.5%) 0.8 (0.5-1.3)
Time to conception of previous pregnancy
0-3 months 350 (93.6) 24 (6.4) Ref 0.26
4-6 months 85 (89.5) 10 (10.5) 1.7 (0.8-3.7)
10-12 months 891 (90.9) 89 (9.1) 1.5 (0.9-2.3)
I don’t remember 29 (93.3) 2 (6.7) 1.0 (0.2-4.6)
Pregnancy was unplanned 452 (89.3) 54 (10.7) 1.7 (1.1-2.9)
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29
Type of contraception used
None 78 (86.7%) 12 (13.3%) Ref 0.50
Barrier method (condom,
diaphragm or IUD)
22 (91.7%) 2 (8.3%) 0.6 (0.1-2.8)
Hormonal method (implant,
injectable or oral pill)
254 (90.1%) 28 (9.9%) 0.7 (0.3-1.5)
Sterilization method+ 1 (100%) 0 Not enough data
Combination (hormonal and
barrier)
681 (90.3%) 73 (9.7%) 0.7 (0.4-1.3)
Number of pregnancies
Never pregnant 363 (87.5) 52 (12.5) 1.9 (1.1-3.4) 0.01
1 pregnancy 469 (90.4) 50 (9.6) 1.4 (0.8-2.5)
2 pregnancies 361 (88.7) 46 (11.3) 1.7 (1.0-3.0)
3 pregnancies 355 (92.0) 31 (8.0) 1.2 (0.7-2.1)
4 pregnancies 257 (93.1) 19 (6.9) 1.2 (0.7-2.2)
> 4 pregnancies 365 (91.7) 33 (8.3) Ref
Number of stillbirths
None 1,708 (91.1) 166 (8.9) Ref 0.02
One or more 463 (87.7) 65 (12.3) 1.4 (1.1-2.0)
Co-infections
Molecular FGS1
Negative 2,037 (90.8) 206 (9.2) Ref 0.007
Positive 133 (84.2) 25 (15.8) 1.9 (1.2-2.9)
Visual FGS by colposcopy2
Negative 947 (89.3) 113 (10.7) Ref 0.28
Positive 527 (91.0) 52 (9.0) 0.8 (0.6-1.2)
HIV status
Negative 1,698 (91.1) 166 (8.9) Ref 0.07
Positive 371 (87.5) 53 (12.5) 1.5 (1.1-2.0)
Unknown 101 (89.4) 12 (10.6) 1.2 (0.7-2.3)
Self-reported antiretroviral therapy (ART) use among HIV-positive
No 30 (81.1) 7 (18.9) 1.8 (0.7-4.2) 0.22
Yes 341 (88.1) 46 (11.9) Ref
Trichomonas (T.) vaginalis status (Ntot=1,556)
Negative 1,842 (91.2) 177 (8.8) Ref 0.004
Positive 205 (85.4) 35 (14.6) 1.8 (1.2-2.6)
S. haematobium by Circulating Anodic Antigen (CAA) (Ntot=1,685)
Negative 1,829 (90.7) 188 (9.3) Ref 0.22
Positive 327 (88.6) 42 (11.4) 1.2 (0.9-1.8)
S. haematobium by urine microscopy (Ntot=1,691)
Negative 2,063 (90.7) 211 (9.3) Ref 0.02
Positive 107 (84.3) 20 (15.8) 1.8 (1.1-3.0)
Percentages (%) on the second and third columns are calculated within each row total. 253
1Molecular FGS refers to PCR diagnosis of either home-based self-collected cervicovaginal swabs or clinic-based provider-254
collected cervicovaginal swabs. 255
2 Visual FGS defined as a positive if confirmed by both reviewers 1 and 2, or in case of disagreement, by reviewer 3. The 256
association between the single visual FGS and infection with HPV16/18/45 are presented in S4 Table 257
Abbreviations: AOR = Adjusted Odds Ratio, CI = Confidence Interval 258
259
260
261
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262
263
The model was adjusted for molecular FGS status, HIV status, T. vaginalis status, district of residence, marital 264
status and number of pregnancies. Abbreviations: aOR=Adjusted Odds Ratio, CI=Confidence Intervals. 265
Figure 4: Multivariable logistic regression model parameter estimates for prevalence of HPV16/18/45 266
as the dependent variable in the study population (N=2,401). 267
268
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31
Table 3: Prevalence of HPV16 only stratified by socio-demographic characteristics and co-269
infections, with univariable logistic regression estimates across the study population (N = 270
2,401). 271
HPV16 Neg
N (%)
HPV16 Pos
N (%)
Crude OR (95%CI) p-value
Total 2,287 (95.3) 114 (4.8)
Socio-demographic characteristics
Age (years)
15-19 296 (95.2) 15 (4.8) 1.1 (0.4-2.9) 0.50
20-25 602 (94.8) 33 (5.2) 1.2 (0.5-2.9)
26-30 504 (95.6) 23 (4.4) 1.0 (0.4-2.5)
31-35 302 (93.5) 21 (6.5) 1.5 (0.6-3.8)
36-40 271 (97.5) 7 (2.5) 0.6 (0.2-1.7)
41-45 182 (95.3) 9 (4.7) 1.1 (0.4-3.1)
46-50 130 (95.6) 6 (4.4) Ref
Marital status
Single 828 (93.5) 58 (6.6) 2.0 (1.3-2.9) 0.03
Married 1,283 (96.5) 46 (3.5) Ref
Divorced/
separated
120 (93.8) 8 (6.3) 1.9 (0.9-4.0)
Widowed 55 (96.5) 2 (3.5) 1.0 (0.2-4.3)
Education
No schooling 45 (97.8) 1 (2.2) Ref 0.38
Some/Completed primary school 815 (95.4) 39 (4.6) 2.2 (0.3-16.0)
Some/completed secondary school 1,218 (95.2) 61 (4.8) 2.3 (0.3-16.6)
Some/completed trade school or
degree
208 (94.1) 13 (5.9) 2.8 (0.4-22.1)
District of residence
Shikoshwe 1,091 (96.2) 43 (3.8) Ref 0.055
Livingstone 1,047 (94.4) 62 (5.6) 1.5 (1.0-2.2)
Chanyanya 149 (94.3) 9 (5.7) 1.5 (0.7-3.2)
Sexual and Reproductive Health Behaviours and Outcomes
Number of sexual partners in the last 6 months
0 118 (94.4%) 7 (5.6%) Ref 0.94
1 1,937 (95.4%) 94 (4.6%) 0.8 (0.4-1.8)
2 134 (93.7%) 9 (6.3%) 1.1 (0.4-3.2)
More than 2 97 (96.0%) 4 (4.0%) 0.7 (0.2-2.5)
Age of sexual debut
20 years-old 257 (97.4%) 7 (2.7%) 0.5 (0.2-1.2)
Time to conception
0-3 months 363 (97.1) 11 (2.9) Ref 0.28
4-6 months 90 (94.7) 5 (5.3) 1.8 (0.6-5.4)
10-12 months 938 (95.7) 42 (4.3) 1.5 (0.8-2.9)
I don’t remember 28 (93.3) 2 (6.7) 2.4 (0.5-11.2)
Pregnancy was unplanned 476 (94.1) 30 (5.9) 2.1 (1.0-4.2)
Type of contraception used
None 84 (93.3%) 6 (6.7%) Ref 0.72
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32
Barrier method (condom,
diaphragm or IUD)
23 (95.8%) 1 (4.2%) 0.6 (0.07-5.3)
Hormonal method (implant,
injectable or oral pill)
268 (95.4%) 13 (4.6%) 0.7 (0.2-1.8)
Sterilization method+ 1 (100%) No data
Combination (hormonal and
barrier)
714 (94.7%) 40 (5.3%) 0.8 (0.32-1.9)
Number of pregnancies
Never pregnant 391 (94.2) 24 (5.8) 1.7 (0.9-3.3) 0.04
1 pregnancy 493 (95.0) 26 (5.0) 1.4 (0.7-2.8)
2 pregnancies 380 (93.4) 27 (6.6) 1.9 (1.0-3.8)
3 pregnancies 373 (96.6) 13 (3.4) 1.0 (0.4-2.1)
4 pregnancies 266 (96.4) 10 (3.6) 1.0 (0.5-2.4)
> 4 pregnancies 384 (96.5) 14 (3.5) Ref
Number of stillbirths
None 1,789 (95.5) 84 (4.5) Ref 0.25
One or more 498 (94.3) 30 (5.7) 1.3 (0.8-2.0)
Co-infections
Molecular FGS1
Negative 2,142 (95.5) 101 (4.5) Ref 0.04
Positive 145 (91.8) 13 (8.2) 1.9 (1.0-3.5)
Visual FGS by point-of-care colposcopy2
Negative 1,003 (94.6) 57 (5.4) Ref 0.27
Positive 555 (95.9) 24 (4.2) 0.8 (0.5-1.2)
HIV status
Negative 1,782 (95.6) 82 (4.4) Ref 0.15
Positive 399 (94.1) 25 (5.9) 1.4 (0.9-2.2)
Unknown 106 (93.8) 7 (6.2) 1.4 (0.6-3.2)
Self-reported antiretroviral therapy (ART) use among HIV-positive
No 35 (94.6) 2 (5.4) Ref 0.89
Yes 364 (94.1) 23 (5.9) 1.1 (0.3-4.9)
Trichomonas (T.) vaginalis status (Ntot=1,556)
Negative 1,927 (95.4) 92 (4.6) Ref 0.25
Positive 225 (93.8) 15 (6.2) 1.4 (0.8-2.5)
S. haematobium by Circulating Anodic Antigen (CAA) (Ntot=1,685)
Negative 1,924 (95.4) 93 (4.6) Ref 0.42
Positive 348 (94.3) 21 (5.7) 1.2 (0.8-2.0)
S. haematobium by urine microscopy (Ntot=1,691)
Negative 2,168 (95.3) 106 (4.7) Ref 0.40
Positive 119 (93.7) 8 (6.3) 1.4 (0.7-2.9)
Percentages (%) on the second and third columns are calculated within each row total.
1 Molecular FGS refers to PCR diagnosis of either home-based self-collected cervicovaginal swabs or clinic-based provider-collected
cervicovaginal swabs.
2 Visual FGS defined as a positive if confirmed by both reviewers 1 and 2, or in case of disagreement, by reviewer 3. The associa tion
between the single visual FGS and infection with HPV16 are presented in S5 Table
Abbreviations: AOR = Adjusted Odds Ratio, CI = Confidence Interval
272
273
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274
The logistic regression model was adjusted for molecular FGS status, marital status and number of pregnancies. 275
Abbreviations: aOR= Adjusted odds ratio, CI= Confidence Intervals 276
Figure 5: Multivariable logistic regression model parameter estimates for prevalence of 277
HPV16 as the dependent variable in the study population (N=2,401). 278
279
280
281
282
283
284
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