Assessment of porcine reproductive and respiratory syndrome virus (PRRSV) farm surface contamination through environmental sampling

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PRRSV can be present on surfaces for prolonged periods, and under certain conditions of temperature, humidity and type of surface, remain viable outside the host. In the United States, the yearly epidemic of PRRSV typically begins in the fall. During the fall of 2020, the variant L1C.5 emerged and rapidly spread throughout southern Minnesota, which generated questions regarding possible transmission routes. This study aimed to investigate whether PRRSV could be detected on surfaces inside and outside pig barns housing L1C.5 variant PRRSV-positive pigs to illustrate the potential for indirect transmission of PRRSV. Results All (n = 26) samples from PRRSV-negative farm tested negative. Nineteen (13%) out of 143 samples from positive farms yielded positive RT-PCR results. Positive samples originated primarily from exhaust fan cones and doorknobs, followed by anteroom floor and mortality carts/sleds. Virus isolation attempted on two samples did not yield positive results. Conclusions PRRSV contamination can occur on surfaces inside and outside pig barns that are in frequent contact with farm personnel. Although virus isolation attempts were negative, our results illustrate the potential for PRRSV to be transmitted indirectly through contaminated materials or farm personnel. The study supports the implementation of biosecurity practices by farm personnel to prevent the introduction of PRRSV into farms and the prevention of PRRSV transmission between farms. PRRS environmental sampling surfaces contamination Background Porcine reproductive and respiratory syndrome (PRRS) is an endemic and costly disease affecting swine in the United States (U.S.) and throughout the world ( 1 , 2 ). The causative agent of the disease is a 15kb single-stranded positive-sense RNA virus belonging to the Arteriviridae family and Arterivirus genus ( 3 , 4 ). The PRRS virus (PRRSV) can be classified into two species, Betaarterivirus suid 1 (PRRSV-1) or Betaarterivirus suid 2 (PRRSV-2) ( 5 ). In the breeding herd, PRRS is characterized by reproductive failure, increased abortions, stillbirths, mummies, premature farrowing, and weak-born piglets. PRRSV also causes respiratory disease characterized by interstitial pneumonia which may result in mortality and poor growth performance ( 6 ). PRRSV can be directly transmitted between infected and susceptible animals through saliva, nasal and oral secretions, feces, urine, semen, and mammary gland secretions. Secretions containing infectious PRRSV can also contaminate inanimate objects which contribute to the indirect transmission of PRRSV ( 7 , 8 ). However, the ability of PRRSV to transmit indirectly depends on environmental conditions such as temperature (-10 to 20°C), pH (6.5 to 7.5), and humidity (17 to 73%), type of virus variant, type of surface, and exposure to chemicals (detergents and lipid solvents) ( 3 , 4 , 6 , 9 – 18 ). Indirect transmission in pigs may occur with exposure to contaminated fomites such as boots, coveralls, needles, and transport vehicles ( 10 , 19 – 25 ), and aerosols ( 17 , 21 , 24 – 26 ). In the U.S. PRRS occurs seasonally with increased incidence typically beginning in October-November and receding into spring ( 29 , 40 ). During the fall of 2020, a new PRRSV variant classified as sub-lineage 1C (L1C.5) emerged in southern Minnesota, and multiple pig farms from various pig production companies were affected. Approximately 6 months later in the spring-summer of 2021, a second wave of PRRSV outbreaks was reported ( 41 ) which was atypical for U.S. PRRS herd infections. Furthermore, farms with robust biosecurity measures (e.g., air filtration, shower in-shower out, disinfection and drying (D&D) room, downtime, Danish entry system) and located in areas considered of low infection risk (i.e., low pig density) became positive with this variant. Because of the rapid transmission of this PRRSV variant throughout a wide geographic area and the absence of specific risk factors associated with this variant’s occurrence ( 32 ), it is hypothesized that farms are becoming infected through indirect routes breaching biosecurity that might differ for each farm. Because there is limited information on what surfaces may be more likely to be contaminated with PRRSV in swine farms, we sampled surfaces considered of high risk of contamination inside and outside farms housing PRRS-L1C.5 positive pigs to better understand the potential risk of PRRSV dissemination from infected premises. Methods Study design This cross-sectional study was conducted during the summer-fall of 2021 and spring of 2022 in which eight farms were conveniently selected. Farm eligibility criteria included: 1) breeding or growing pig farms representative of modern pig production practices in the U.S., 2) laboratory confirmation by RT-PCR and ORF5 sequencing that pigs were infected with PRRSV L1C.5 variant, 3) pigs were in the early stages of the outbreak (i.e., 4 to 5 weeks post-estimated virus introduction), and 4) farms located in the Midwestern U.S. In addition, one PRRSV negative (i.e., PRRSV naïve, AASV Breeding herd classification status 4) farm located in the epicenter of the outbreak and in a high pig-dense area was identified and included in the study as a negative control. Sample size and surfaces The study was designed to assess whether PRRSV RNA could be detected on different surfaces of pig farms through RT-PCR. Given that, there were no available protocols for assessing viral contamination in pig farms, a sampling methodology was developed in conjunction with practicing veterinarians. A maximum of 29 samples per farm were collected. This sample size allowed a 95% confidence level in detecting at least one positive sample when the prevalence of positive surfaces was estimated to be at least 10%. Surfaces included for sampling were not in direct contact with pigs and were chosen based on the likelihood of contamination (Table 1 ), materials present at the farm (e.g., rubber, concrete, plastic, wood, metal cloth) (18,42–45) and risk that these surfaces could then be in contact with farm personnel. Table 1 Sampling approach to detect PRRSV on surfaces from United States Midwestern pig farms housing PRRSV-positive pigs. Sampling areas Number of Samples Breeding farm Growing/finishing farm Employee vehicles Exterior door handles 6 to 12* 2 to 4* Pedals and footrest 9 3 Car exterior surfaces (roof, trunk, door facing the farm) 3 3 Main Entrance doorknobs Exterior and interior doorknobs of the farm’s main entrance door 1 1 Both doorknobs of the door used to bring mortality out of the barn 1 1 Anteroom Floor directly in front of the main door 1 1 Floor closest to the bench or shower door 1 1 D&D Room Floor inside the D&D room area directly in front of the exterior door Both doorknobs of the exterior door of the room 1 1 1 1 Exhaust fan housing Fan housing and fan louvers/shutters 3 2 Loading chute Edge (that comes in contact with the trailer) of the loading ramp. 1 1 Particle deposition Aluminum foil in 4 locations around the farm (North, South, West, and East) 30 meters away from the barn. 4 4 Other Mortality sled or cart 1 1 *Quantity depended on the number of vehicles present during the sampling day. Environmental sample collection Investigators wore disposable protective suits (Tyvek®, Dupont™, Wilmington, DE) and plastic boot covers upon arrival at the farm site and before getting out of the vehicle. Hands were cleaned with disinfectant wipes (e.g., Lysol®, Reckitt Benckiser Group, Slough, England) between samples. A clean set of nitrile rubber gloves was worn before collecting each sample. Samples were collected using a previously validated environmental sampling protocol for PRRSV (46,47). Briefly, under clean laboratory conditions a sterile gauze or dry cloth (Swiffer®, P&G, Cincinnati, OH) was placed inside a new resealable plastic bag (Ziploc®, S.C. Johnson, Racine, WI) and moistened with 20 mL of phosphate-buffered saline (PBS) solution. Using new disposable nitrile rubber gloves, the cloth was removed from the resealable bag at the farm, the surface was wiped and the cloth was placed back into the original bag and sealed. The bag, together with the cloth, were squeezed and the excess fluid was poured into a sterile plastic falcon tube (Corning Falcon®, Thermo Fisher Scientific Inc., Waltham, MA). Samples were labeled with a specific identifier according to the surface wiped, farm identification number and placed into a refrigerated container. Samples were collected using a 2-step approach. First, four locations around the pig barn representing the cardinal points were chosen. At each of these locations, a sheet of aluminum foil paper (1m x 0.3m) was placed on the ground 30 m away from the barn. The aluminum foil paper was then wiped with the sampling gauze 60 minutes after placement. Second, outside the barns and in the anteroom flooring, surface samples were then collected by wiping a 0.30 m x 0.30 m area of the surface (e.g., floor) or the whole surface (e.g., doorknobs, door handles, car pedals). Sample testing Samples were transported to the University of Minnesota Veterinary Diagnostic Laboratory (UMN-VDL) for PRRSV RT-PCR testing. Based on UMN-VDL protocols, samples below an RT-PCR cycle threshold (Ct) value of 40 were considered positive. Virus isolation (VI) was attempted on MARC-145 and porcine alveolar macrophages (PAM) from samples yielding a Ct value below 30. Results A total of 169 environmental samples were collected from all 8 farms, 75 from three breeding herds, and 94 from growing pig farms (i.e., nursery or wean-to-market farms). The number of samples collected on each farm was affected by the presence or absence of specific sampling surfaces (e.g., two-door vehicles instead of four-door, absence of D&D room, absence of vehicles during visit). From the negative control breeding farm, all 26 samples yielded RT-PCR negative results. In six out of the seven farms housing PRRSV-positive pigs, at least one surface yielded an RT-PCR-positive result. Of the 143 samples obtained from positive farms, 19 (13.2%) samples yielded RT-PCR positive results with Ct values ranging between 25.4 and 37.0 (Table 2 ). Of the 19 positive samples, 15 (79%) originated from non-porous surfaces such as plastic or metal whereas 4 (21%) from porous materials such as concrete. Eight (42%) out of the 19 positive samples originated from exhaust fan cones in four farms and had a Ct value ranging from 30.3 to 37.0. The main door entry doorknobs or the doorknobs of the door leading to the mortality disposal corridor at three farms tested RT-PCR positive with Ct values ranging between 34.2 and 36.4. The remaining positive samples, eight, originated from surfaces from the anteroom floor and mortality carts/sleds with Ct values ranging from 25.4 to 35.4. None of the foil paper particle deposition samples tested positive for PRRSV. Two samples originated from mortality sleds had a Ct value below 30 and were further tested by virus isolation on MARC-145 and PAM cells, yielding negative results. Table 2 Proportion and cycle threshold values of PRRSV RT-PCR positive samples by site, and location within farm. Farm ID Farm type Herd size Proportion of positive samples Location of each positive sample PRRSV RT-PCR Cycle threshold (Ct) values 1* Breeding* 1500 0/26 (0%) -- -- 2 Breeding 900 2/26 (8%) Exhaust fan cone 30.3 Exhaust fan cone 37.0 3 Nursery/Finisher 2400–4800 1/23 (4%) Exhaust fan cone 35.9 4 Breeding 2678 0/23 (0%) -- -- 5 Nursery 6600 5/23 (22%) Exhaust fan cone 34.0 Exhaust fan cone 34.4 Exhaust fan cone 36.0 Anteroom floor next to the bench's dirty side 35.4 Mortality doorknob 36.4 6 Nursery 2400 1/15 (7%) Main entrance doorknob 34.2 7 Wean-to-market 2400 2/18 (11%) Mortality loading chute internal floor 31.7 Mortality sled** 25.4 8 Wean-to-market 2400 8/15 (53%) Exhaust fan cone 32.3 Exhaust fan cone 34.8 Mortality loading chute internal doorknob 35.0 Anteroom floor closest to the side of the line of separation to pens 33.6 Mortality sled #1** 28.7 Mortality sled #2 handle 33.3 Mortality sled #2 33.7 Outside barn entrance floor 31.5 *Negative control farm, **Samples submitted for virus isolation Discussion Our study confirmed that detecting PRRSV RNA from surfaces in farms undergoing a PRRSV L1C.5 variant outbreak was possible. The surfaces were not in direct contact with pigs and represented surfaces that employees frequently come in contact with (e.g., doorknobs and anteroom flooring). Our results highlight the importance of barn entry and exit processes directed at limiting the contact of personnel with contaminated surfaces. Even though efforts were made to assess whether the virus was viable by virus isolation, none of the tested samples yielded positive results. Viability data of swine viruses on surfaces exists for influenza A virus (IAV) and porcine epidemic diarrhea virus (PEDV), concluding that these can remain viable longer on nonporous surfaces when compared to porous surfaces (48,49). Failure to detect viable virus could be the result of damaged RNA due to factors such as UV-light exposure, desiccation, time of exposure, humidity, and temperature ( 3 , 4 , 6 , 9 , 11 , 41 ). In addition, it was not known for how long these viral particles had been present on these surfaces prior to sample collection, which ultimately could have limited the probability of detecting virus. Almost half (42%) of the RT-PCR positive results originated from exhaust fan cones which indicated that virus particles originating from animals became airborne and were expelled from the barn through the exhaust fans and some were deposited on the cone surface. This information suggests that biocontainment of PRRSV can be complex and environmental contamination can occur in the immediate vicinity of the affected farms. Even though our study detected viral RNA on exhaust fan cone surfaces, our particle deposition sampling did not yield positive results. This conflicting result could be due to a dilution effect, or dispersion over greater distances because of wind gusts during sampling or limited sampling time. Furthermore, viral particles on exhaust fan cone surfaces had accumulated for a longer time and had higher proximity with infected pigs when compared to our aluminum foil particle deposition approach which ultimately may have led to the virus being detected. Detecting PRRSV RNA on surfaces that farm personnel contact frequently was revealing. Surfaces such as the anteroom floor or doorknobs had positive RT-PCR results which can be the result of farm personnel likely contaminating these surfaces through footwear, dirty gloves, or hands. The detection of viral RNA on the floor closest to the bench in the anteroom is concerning from a biocontainment perspective. This finding could be the result of employees either bringing the virus into the farm through contaminated footwear or contaminated footwear being moved across the bench from the clean side towards the dirty side of the bench. Another possibility is that airborne virus could have settled on these surfaces. In the case of doorknobs, employees can easily contaminate their hands or gloves during pig or equipment handling and subsequently transfer the virus to doorknobs. Otake, (2002) and Pitkin et al., (2009) were able to detect PRRSV by RT-PCR in samples obtained from coveralls, boots, hands, feed bags, cable snare, and blood-testing supplies; however, viable virus was not recovered. Therefore, our results agree with previous reports and continue to highlight the fact that the virus can potentially be transported by farm personnel out of the barns which becomes a risk for PRRSV dissemination. Findings from this study underscore the importance of biocontainment during PRRSV outbreaks. Detecting viral RNA on samples outside the barn (e.g., exhaust fan cones, mortality sled, anteroom floor, outside the barn floor) indicates that the virus is potentially being carried outside the barn which may ultimately lead to increased risk to neighboring farms. The mortality sled being contaminated with PRRSV during an outbreak or weeks after may be expected because its surfaces come in direct contact with blood, secretions, and excretions containing high viral loads. These surfaces may be considered a source of virus but also highlight the need for a better understanding of the risks related to mortality management, especially processes related to dead animal removal from the barn and dead pig transport to the mortality pick-up location. Additional data is needed to assess the presence and PRRSV viability on the surface of the mortality sled and mortality pick-up locations under different environmental conditions. As with any research study, our study has limitations. Our sampling protocol was designed using current environmental sampling knowledge and likely our sample size may have led us to underestimate the detection of the virus on surfaces. In addition, the protocol was calculated to originally collect a minimum of 209 samples, and only 169 samples were collected, mostly from the lack of presence of the targeted areas, which can affect the power of the study. Another limitation is the fact that even though we knew the population of pigs housed in these barns was undergoing an outbreak we did not know the extent of viral shedding by the animals at the time of collection, which can play a role in environmental contamination. Conclusions In summary, the detection of PRRSV genetic material on surfaces on the inside and outside areas of a farm housing PRRSV-positive pigs is possible using targeted surface sampling. This exploratory study provides evidence that biocontainment efforts to prevent the spread of PRRSV from infected farms are necessary. Declarations Ethics approval and consent to participate: Not applicable Consent for publication: Not applicable Competing interests: The authors declare that they have no competing interests. Funding: This project was funded by the University of Minnesota Swine Disease Eradication Center (SDEC). Author Contribution CMM: Writing – original draft, Formal Analysis; MK: Writing – review & editing; MT: Conceptualization, Funding acquisition, Writing – review & editing; LB: Conceptualization, Writing - review & editing; CS: Writing - review & editing; BR: Writing - review & editing; PY: Conceptualization, Writing - review & editing; BL: Writing - review & editing; MA: Conceptualization, Writing - review & editing; KO: Writing - review & editing; MS: Writing - review & editing; CAC: Conceptualization, Funding acquisition, Writing – review & editing. All authors reviewed the manuscript. 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Cite Share Download PDF Status: Published Journal Publication published 27 Sep, 2024 Read the published version in Porcine Health Management → Version 1 posted Editorial decision: Revision requested 11 Aug, 2024 Reviews received at journal 10 Aug, 2024 Reviewers agreed at journal 26 Jul, 2024 Reviewers invited by journal 23 Jul, 2024 Editor assigned by journal 22 Jul, 2024 Submission checks completed at journal 22 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. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. We do this by developing innovative software and high quality services for the global research community. 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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-4784873","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":338692221,"identity":"6cbcd371-4137-4b92-a34a-ae119a5705d3","order_by":0,"name":"Claudio Marcello Melini","email":"","orcid":"","institution":"University of Minnesota","correspondingAuthor":false,"prefix":"","firstName":"Claudio","middleName":"Marcello","lastName":"Melini","suffix":""},{"id":338692222,"identity":"79f717f8-0020-46bc-889a-11981a4fe72b","order_by":1,"name":"Mariana Kikuti","email":"","orcid":"","institution":"University of Minnesota","correspondingAuthor":false,"prefix":"","firstName":"Mariana","middleName":"","lastName":"Kikuti","suffix":""},{"id":338692223,"identity":"f5a52bc8-0978-48e4-a4ad-a4cda3898f68","order_by":2,"name":"Laura Bruner","email":"","orcid":"","institution":"Swine Vet Center","correspondingAuthor":false,"prefix":"","firstName":"Laura","middleName":"","lastName":"Bruner","suffix":""},{"id":338692224,"identity":"21c1b5c2-a058-46ff-889c-7d87e32bdc48","order_by":3,"name":"Matt Allerson","email":"","orcid":"","institution":"Holden Farms Inc","correspondingAuthor":false,"prefix":"","firstName":"Matt","middleName":"","lastName":"Allerson","suffix":""},{"id":338692225,"identity":"85cb56c9-ba76-4394-9f37-c4002e9e7ad6","order_by":4,"name":"Katie O’Brien","email":"","orcid":"","institution":"Holden Farms Inc","correspondingAuthor":false,"prefix":"","firstName":"Katie","middleName":"","lastName":"O’Brien","suffix":""},{"id":338692226,"identity":"c4aff97b-66ce-4b07-9d83-cc00f585d670","order_by":5,"name":"Chase Stahl","email":"","orcid":"","institution":"Fairmont Vet Clinic","correspondingAuthor":false,"prefix":"","firstName":"Chase","middleName":"","lastName":"Stahl","suffix":""},{"id":338692227,"identity":"7d4b0009-6859-4399-869a-facb2881260d","order_by":6,"name":"Brian Roggow","email":"","orcid":"","institution":"Fairmont Vet Clinic","correspondingAuthor":false,"prefix":"","firstName":"Brian","middleName":"","lastName":"Roggow","suffix":""},{"id":338692228,"identity":"bc7207ad-af8b-4915-a185-7dde6b441f3a","order_by":7,"name":"Paul Yeske","email":"","orcid":"","institution":"Swine Vet Center","correspondingAuthor":false,"prefix":"","firstName":"Paul","middleName":"","lastName":"Yeske","suffix":""},{"id":338692229,"identity":"c28a7be4-ee9c-4336-808f-ec5d253660d2","order_by":8,"name":"Brad Leuwerke","email":"","orcid":"","institution":"Swine Vet Center","correspondingAuthor":false,"prefix":"","firstName":"Brad","middleName":"","lastName":"Leuwerke","suffix":""},{"id":338692230,"identity":"03b7c779-e9ba-4836-b014-f99bba9b6457","order_by":9,"name":"Mark Schwartz","email":"","orcid":"","institution":"University of Minnesota","correspondingAuthor":false,"prefix":"","firstName":"Mark","middleName":"","lastName":"Schwartz","suffix":""},{"id":338692231,"identity":"bd496578-571a-42b9-8ee0-8c96df5a855f","order_by":10,"name":"Montserrat Torremorell","email":"","orcid":"","institution":"University of Minnesota","correspondingAuthor":false,"prefix":"","firstName":"Montserrat","middleName":"","lastName":"Torremorell","suffix":""},{"id":338692232,"identity":"e0765f9f-d746-4094-89b8-9cb3c9deb20b","order_by":11,"name":"Cesar A. Corzo","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAAl0lEQVRIiWNgGAWjYNCCCgglQYKWMyRrYWwjRQt/e+/jDx/nHY42Z2A+eJuHGC0SZ44bGM7cdjh3ZwNbsjVRWgwk0hiSeYFaNhzgMZMmWsth3jkgLfzfiNbC2MzbALaFjTgtEmeOMTPOOJaeu+Ewm7HlHGK08Le3MX/4UGOdu+F488Mbb4jRggDMpCkfBaNgFIyCUYAPAABVoC6O9Xj8BgAAAABJRU5ErkJggg==","orcid":"","institution":"University of Minnesota","correspondingAuthor":true,"prefix":"","firstName":"Cesar","middleName":"A.","lastName":"Corzo","suffix":""}],"badges":[],"createdAt":"2024-07-23 01:39:19","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-4784873/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-4784873/v1","draftVersion":[],"editorialEvents":[{"content":"https://doi.org/10.1186/s40813-024-00387-5","type":"published","date":"2024-09-27T15:58:00+00:00"}],"editorialNote":"","failedWorkflow":false,"files":[{"id":65628077,"identity":"7b38cc60-b9ef-4b9b-a843-224c63e48975","added_by":"auto","created_at":"2024-09-30 16:17:40","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":492956,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-4784873/v1/22c22bec-8233-4e58-9278-608332366c23.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"Assessment of porcine reproductive and respiratory syndrome virus (PRRSV) farm surface contamination through environmental sampling","fulltext":[{"header":"Background","content":"\u003cp\u003ePorcine reproductive and respiratory syndrome (PRRS) is an endemic and costly disease affecting swine in the United States (U.S.) and throughout the world (\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e, \u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e). The causative agent of the disease is a 15kb single-stranded positive-sense RNA virus belonging to the \u003cem\u003eArteriviridae\u003c/em\u003e family and \u003cem\u003eArterivirus\u003c/em\u003e genus (\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e, \u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e). The PRRS virus (PRRSV) can be classified into two species, \u003cem\u003eBetaarterivirus suid 1\u003c/em\u003e (PRRSV-1) or \u003cem\u003eBetaarterivirus suid 2\u003c/em\u003e (PRRSV-2) (\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e). In the breeding herd, PRRS is characterized by reproductive failure, increased abortions, stillbirths, mummies, premature farrowing, and weak-born piglets. PRRSV also causes respiratory disease characterized by interstitial pneumonia which may result in mortality and poor growth performance (\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e).\u003c/p\u003e \u003cp\u003ePRRSV can be directly transmitted between infected and susceptible animals through saliva, nasal and oral secretions, feces, urine, semen, and mammary gland secretions. Secretions containing infectious PRRSV can also contaminate inanimate objects which contribute to the indirect transmission of PRRSV (\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e, \u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e). However, the ability of PRRSV to transmit indirectly depends on environmental conditions such as temperature (-10 to 20\u0026deg;C), pH (6.5 to 7.5), and humidity (17 to 73%), type of virus variant, type of surface, and exposure to chemicals (detergents and lipid solvents) (\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e, \u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e, \u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e, \u003cspan additionalcitationids=\"CR10 CR11 CR12 CR13 CR14 CR15 CR16 CR17\" citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e). Indirect transmission in pigs may occur with exposure to contaminated fomites such as boots, coveralls, needles, and transport vehicles (\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e, \u003cspan additionalcitationids=\"CR20 CR21 CR22 CR23 CR24\" citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e25\u003c/span\u003e), and aerosols (\u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e, \u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e21\u003c/span\u003e, \u003cspan additionalcitationids=\"CR25\" citationid=\"CR24\" class=\"CitationRef\"\u003e24\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR26\" class=\"CitationRef\"\u003e26\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eIn the U.S. PRRS occurs seasonally with increased incidence typically beginning in October-November and receding into spring (\u003cspan citationid=\"CR29\" class=\"CitationRef\"\u003e29\u003c/span\u003e, \u003cspan citationid=\"CR40\" class=\"CitationRef\"\u003e40\u003c/span\u003e). During the fall of 2020, a new PRRSV variant classified as sub-lineage 1C (L1C.5) emerged in southern Minnesota, and multiple pig farms from various pig production companies were affected. Approximately 6 months later in the spring-summer of 2021, a second wave of PRRSV outbreaks was reported (\u003cspan citationid=\"CR41\" class=\"CitationRef\"\u003e41\u003c/span\u003e) which was atypical for U.S. PRRS herd infections. Furthermore, farms with robust biosecurity measures (e.g., air filtration, shower in-shower out, disinfection and drying (D\u0026amp;D) room, downtime, Danish entry system) and located in areas considered of low infection risk (i.e., low pig density) became positive with this variant. Because of the rapid transmission of this PRRSV variant throughout a wide geographic area and the absence of specific risk factors associated with this variant\u0026rsquo;s occurrence (\u003cspan citationid=\"CR32\" class=\"CitationRef\"\u003e32\u003c/span\u003e), it is hypothesized that farms are becoming infected through indirect routes breaching biosecurity that might differ for each farm.\u003c/p\u003e \u003cp\u003eBecause there is limited information on what surfaces may be more likely to be contaminated with PRRSV in swine farms, we sampled surfaces considered of high risk of contamination inside and outside farms housing PRRS-L1C.5 positive pigs to better understand the potential risk of PRRSV dissemination from infected premises.\u003c/p\u003e"},{"header":"Methods","content":"\u003cp\u003eStudy design\u003c/p\u003e \u003cp\u003eThis cross-sectional study was conducted during the summer-fall of 2021 and spring of 2022 in which eight farms were conveniently selected. Farm eligibility criteria included: 1) breeding or growing pig farms representative of modern pig production practices in the U.S., 2) laboratory confirmation by RT-PCR and ORF5 sequencing that pigs were infected with PRRSV L1C.5 variant, 3) pigs were in the early stages of the outbreak (i.e., 4 to 5 weeks post-estimated virus introduction), and 4) farms located in the Midwestern U.S. In addition, one PRRSV negative (i.e., PRRSV na\u0026iuml;ve, AASV Breeding herd classification status 4) farm located in the epicenter of the outbreak and in a high pig-dense area was identified and included in the study as a negative control.\u003c/p\u003e \u003cp\u003eSample size and surfaces\u003c/p\u003e \u003cp\u003eThe study was designed to assess whether PRRSV RNA could be detected on different surfaces of pig farms through RT-PCR. Given that, there were no available protocols for assessing viral contamination in pig farms, a sampling methodology was developed in conjunction with practicing veterinarians. A maximum of 29 samples per farm were collected. This sample size allowed a 95% confidence level in detecting at least one positive sample when the prevalence of positive surfaces was estimated to be at least 10%. Surfaces included for sampling were not in direct contact with pigs and were chosen based on the likelihood of contamination (Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e), materials present at the farm (e.g., rubber, concrete, plastic, wood, metal cloth) (18,42\u0026ndash;45) and risk that these surfaces could then be in contact with farm personnel.\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\u003eSampling approach to detect PRRSV on surfaces from United States Midwestern pig farms housing PRRSV-positive pigs.\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=\"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 \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colspan=\"2\" morerows=\"1\" nameend=\"c2\" namest=\"c1\" rowspan=\"2\"\u003e \u003cp\u003eSampling areas\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colspan=\"2\" nameend=\"c4\" namest=\"c3\"\u003e \u003cp\u003eNumber of Samples\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eBreeding farm\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003eGrowing/finishing farm\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colspan=\"4\" nameend=\"c4\" namest=\"c1\"\u003e \u003cp\u003eEmployee vehicles\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eExterior door handles\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e6 to 12*\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e2 to 4*\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003ePedals and footrest\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e9\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e3\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eCar exterior surfaces (roof, trunk, door facing the farm)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e3\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colspan=\"4\" nameend=\"c4\" namest=\"c1\"\u003e \u003cp\u003eMain Entrance doorknobs\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eExterior and interior doorknobs of the farm\u0026rsquo;s main entrance door\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\u003e1\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eBoth doorknobs of the door used to bring mortality out of the barn\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\u003e1\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colspan=\"4\" nameend=\"c4\" namest=\"c1\"\u003e \u003cp\u003eAnteroom\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eFloor directly in front of the main door\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\u003e1\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eFloor closest to the bench or shower door\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\u003e1\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colspan=\"4\" nameend=\"c4\" namest=\"c1\"\u003e \u003cp\u003eD\u0026amp;D Room\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eFloor inside the D\u0026amp;D room area directly in front of the exterior door\u003c/p\u003e \u003cp\u003eBoth doorknobs of the exterior door of the room\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e1\u003c/p\u003e \u003cp\u003e1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e1\u003c/p\u003e \u003cp\u003e1\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colspan=\"4\" nameend=\"c4\" namest=\"c1\"\u003e \u003cp\u003eExhaust fan housing\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eFan housing and fan louvers/shutters\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e2\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colspan=\"4\" nameend=\"c4\" namest=\"c1\"\u003e \u003cp\u003eLoading chute\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eEdge (that comes in contact with the trailer) of the loading ramp.\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\u003e1\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colspan=\"4\" nameend=\"c4\" namest=\"c1\"\u003e \u003cp\u003eParticle deposition\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eAluminum foil in 4 locations around the farm (North, South, West, and East) 30 meters away from the barn.\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e4\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colspan=\"4\" nameend=\"c4\" namest=\"c1\"\u003e \u003cp\u003eOther\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eMortality sled or cart\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\u003e1\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*Quantity depended on the number of vehicles present during the sampling day.\u003c/p\u003e \u003cp\u003eEnvironmental sample collection\u003c/p\u003e \u003cp\u003eInvestigators wore disposable protective suits (Tyvek\u0026reg;, Dupont\u0026trade;, Wilmington, DE) and plastic boot covers upon arrival at the farm site and before getting out of the vehicle. Hands were cleaned with disinfectant wipes (e.g., Lysol\u0026reg;, Reckitt Benckiser Group, Slough, England) between samples. A clean set of nitrile rubber gloves was worn before collecting each sample. Samples were collected using a previously validated environmental sampling protocol for PRRSV (46,47). Briefly, under clean laboratory conditions a sterile gauze or dry cloth (Swiffer\u0026reg;, P\u0026amp;G, Cincinnati, OH) was placed inside a new resealable plastic bag (Ziploc\u0026reg;, S.C. Johnson, Racine, WI) and moistened with 20 mL of phosphate-buffered saline (PBS) solution. Using new disposable nitrile rubber gloves, the cloth was removed from the resealable bag at the farm, the surface was wiped and the cloth was placed back into the original bag and sealed. The bag, together with the cloth, were squeezed and the excess fluid was poured into a sterile plastic falcon tube (Corning Falcon\u0026reg;, Thermo Fisher Scientific Inc., Waltham, MA). Samples were labeled with a specific identifier according to the surface wiped, farm identification number and placed into a refrigerated container.\u003c/p\u003e \u003cp\u003eSamples were collected using a 2-step approach. First, four locations around the pig barn representing the cardinal points were chosen. At each of these locations, a sheet of aluminum foil paper (1m x 0.3m) was placed on the ground 30 m away from the barn. The aluminum foil paper was then wiped with the sampling gauze 60 minutes after placement. Second, outside the barns and in the anteroom flooring, surface samples were then collected by wiping a 0.30 m x 0.30 m area of the surface (e.g., floor) or the whole surface (e.g., doorknobs, door handles, car pedals).\u003c/p\u003e \u003cp\u003eSample testing\u003c/p\u003e \u003cp\u003eSamples were transported to the University of Minnesota Veterinary Diagnostic Laboratory (UMN-VDL) for PRRSV RT-PCR testing. Based on UMN-VDL protocols, samples below an RT-PCR cycle threshold (Ct) value of 40 were considered positive. Virus isolation (VI) was attempted on MARC-145 and porcine alveolar macrophages (PAM) from samples yielding a Ct value below 30.\u003c/p\u003e"},{"header":"Results","content":"\u003cp\u003eA total of 169 environmental samples were collected from all 8 farms, 75 from three breeding herds, and 94 from growing pig farms (i.e., nursery or wean-to-market farms). The number of samples collected on each farm was affected by the presence or absence of specific sampling surfaces (e.g., two-door vehicles instead of four-door, absence of D\u0026amp;D room, absence of vehicles during visit).\u003c/p\u003e \u003cp\u003eFrom the negative control breeding farm, all 26 samples yielded RT-PCR negative results. In six out of the seven farms housing PRRSV-positive pigs, at least one surface yielded an RT-PCR-positive result. Of the 143 samples obtained from positive farms, 19 (13.2%) samples yielded RT-PCR positive results with Ct values ranging between 25.4 and 37.0 (Table\u0026nbsp;\u003cspan refid=\"Tab2\" class=\"InternalRef\"\u003e2\u003c/span\u003e). Of the 19 positive samples, 15 (79%) originated from non-porous surfaces such as plastic or metal whereas 4 (21%) from porous materials such as concrete. Eight (42%) out of the 19 positive samples originated from exhaust fan cones in four farms and had a Ct value ranging from 30.3 to 37.0. The main door entry doorknobs or the doorknobs of the door leading to the mortality disposal corridor at three farms tested RT-PCR positive with Ct values ranging between 34.2 and 36.4. The remaining positive samples, eight, originated from surfaces from the anteroom floor and mortality carts/sleds with Ct values ranging from 25.4 to 35.4. None of the foil paper particle deposition samples tested positive for PRRSV.\u003c/p\u003e \u003cp\u003eTwo samples originated from mortality sleds had a Ct value below 30 and were further tested by virus isolation on MARC-145 and PAM cells, yielding negative results.\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\u003eProportion and cycle threshold values of PRRSV RT-PCR positive samples by site, and location within farm.\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 \u003cp\u003eFarm ID\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eFarm type\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eHerd\u003c/p\u003e \u003cp\u003esize\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003eProportion of positive samples\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c5\"\u003e \u003cp\u003eLocation of each positive sample\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c6\"\u003e \u003cp\u003ePRRSV RT-PCR Cycle threshold (Ct) values\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e1*\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eBreeding*\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e1500\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0/26 (0%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e--\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e--\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\" morerows=\"1\" rowspan=\"2\"\u003e \u003cp\u003e2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\" morerows=\"1\" rowspan=\"2\"\u003e \u003cp\u003eBreeding\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\" morerows=\"1\" rowspan=\"2\"\u003e \u003cp\u003e900\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\" morerows=\"1\" rowspan=\"2\"\u003e \u003cp\u003e2/26 (8%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003eExhaust fan cone\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e30.3\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003eExhaust fan cone\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e37.0\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eNursery/Finisher\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e2400\u0026ndash;4800\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e1/23 (4%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003eExhaust fan cone\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e35.9\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eBreeding\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e2678\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0/23 (0%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e--\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e--\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\" morerows=\"4\" rowspan=\"5\"\u003e \u003cp\u003e5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\" morerows=\"4\" rowspan=\"5\"\u003e \u003cp\u003eNursery\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\" morerows=\"4\" rowspan=\"5\"\u003e \u003cp\u003e6600\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\" morerows=\"4\" rowspan=\"5\"\u003e \u003cp\u003e5/23 (22%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003eExhaust fan cone\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e34.0\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003eExhaust fan cone\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e34.4\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003eExhaust fan cone\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e36.0\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003eAnteroom floor next to the bench's dirty side\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e35.4\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003eMortality doorknob\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e36.4\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eNursery\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e2400\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e1/15 (7%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003eMain entrance doorknob\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e34.2\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\" morerows=\"1\" rowspan=\"2\"\u003e \u003cp\u003e7\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\" morerows=\"1\" rowspan=\"2\"\u003e \u003cp\u003eWean-to-market\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\" morerows=\"1\" rowspan=\"2\"\u003e \u003cp\u003e2400\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\" morerows=\"1\" rowspan=\"2\"\u003e \u003cp\u003e2/18 (11%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003eMortality loading chute internal floor\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e31.7\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003eMortality sled**\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e25.4\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\" morerows=\"7\" rowspan=\"8\"\u003e \u003cp\u003e8\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\" morerows=\"7\" rowspan=\"8\"\u003e \u003cp\u003eWean-to-market\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\" morerows=\"7\" rowspan=\"8\"\u003e \u003cp\u003e2400\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\" morerows=\"7\" rowspan=\"8\"\u003e \u003cp\u003e8/15 (53%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003eExhaust fan cone\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e32.3\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003eExhaust fan cone\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e34.8\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003eMortality loading chute internal doorknob\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e35.0\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003eAnteroom floor closest to the side of the line of separation to pens\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e33.6\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003eMortality sled #1**\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e28.7\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003eMortality sled #2 handle\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e33.3\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003eMortality sled #2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e33.7\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003eOutside barn entrance floor\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e31.5\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003ctfoot\u003e \u003ctr\u003e\u003ctd colspan=\"6\"\u003e*Negative control farm, **Samples submitted for virus isolation\u003c/td\u003e\u003c/tr\u003e \u003c/tfoot\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e"},{"header":"Discussion","content":"\u003cp\u003eOur study confirmed that detecting PRRSV RNA from surfaces in farms undergoing a PRRSV L1C.5 variant outbreak was possible. The surfaces were not in direct contact with pigs and represented surfaces that employees frequently come in contact with (e.g., doorknobs and anteroom flooring). Our results highlight the importance of barn entry and exit processes directed at limiting the contact of personnel with contaminated surfaces.\u003c/p\u003e \u003cp\u003eEven though efforts were made to assess whether the virus was viable by virus isolation, none of the tested samples yielded positive results. Viability data of swine viruses on surfaces exists for influenza A virus (IAV) and porcine epidemic diarrhea virus (PEDV), concluding that these can remain viable longer on nonporous surfaces when compared to porous surfaces (48,49). Failure to detect viable virus could be the result of damaged RNA due to factors such as UV-light exposure, desiccation, time of exposure, humidity, and temperature (\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e, \u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e, \u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e, \u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e, \u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e, \u003cspan citationid=\"CR41\" class=\"CitationRef\"\u003e41\u003c/span\u003e). In addition, it was not known for how long these viral particles had been present on these surfaces prior to sample collection, which ultimately could have limited the probability of detecting virus.\u003c/p\u003e \u003cp\u003eAlmost half (42%) of the RT-PCR positive results originated from exhaust fan cones which indicated that virus particles originating from animals became airborne and were expelled from the barn through the exhaust fans and some were deposited on the cone surface. This information suggests that biocontainment of PRRSV can be complex and environmental contamination can occur in the immediate vicinity of the affected farms. Even though our study detected viral RNA on exhaust fan cone surfaces, our particle deposition sampling did not yield positive results. This conflicting result could be due to a dilution effect, or dispersion over greater distances because of wind gusts during sampling or limited sampling time. Furthermore, viral particles on exhaust fan cone surfaces had accumulated for a longer time and had higher proximity with infected pigs when compared to our aluminum foil particle deposition approach which ultimately may have led to the virus being detected.\u003c/p\u003e \u003cp\u003eDetecting PRRSV RNA on surfaces that farm personnel contact frequently was revealing. Surfaces such as the anteroom floor or doorknobs had positive RT-PCR results which can be the result of farm personnel likely contaminating these surfaces through footwear, dirty gloves, or hands. The detection of viral RNA on the floor closest to the bench in the anteroom is concerning from a biocontainment perspective. This finding could be the result of employees either bringing the virus into the farm through contaminated footwear or contaminated footwear being moved across the bench from the clean side towards the dirty side of the bench. Another possibility is that airborne virus could have settled on these surfaces. In the case of doorknobs, employees can easily contaminate their hands or gloves during pig or equipment handling and subsequently transfer the virus to doorknobs. Otake, (2002) and Pitkin et al., (2009) were able to detect PRRSV by RT-PCR in samples obtained from coveralls, boots, hands, feed bags, cable snare, and blood-testing supplies; however, viable virus was not recovered. Therefore, our results agree with previous reports and continue to highlight the fact that the virus can potentially be transported by farm personnel out of the barns which becomes a risk for PRRSV dissemination.\u003c/p\u003e \u003cp\u003eFindings from this study underscore the importance of biocontainment during PRRSV outbreaks. Detecting viral RNA on samples outside the barn (e.g., exhaust fan cones, mortality sled, anteroom floor, outside the barn floor) indicates that the virus is potentially being carried outside the barn which may ultimately lead to increased risk to neighboring farms. The mortality sled being contaminated with PRRSV during an outbreak or weeks after may be expected because its surfaces come in direct contact with blood, secretions, and excretions containing high viral loads. These surfaces may be considered a source of virus but also highlight the need for a better understanding of the risks related to mortality management, especially processes related to dead animal removal from the barn and dead pig transport to the mortality pick-up location. Additional data is needed to assess the presence and PRRSV viability on the surface of the mortality sled and mortality pick-up locations under different environmental conditions.\u003c/p\u003e \u003cp\u003eAs with any research study, our study has limitations. Our sampling protocol was designed using current environmental sampling knowledge and likely our sample size may have led us to underestimate the detection of the virus on surfaces. In addition, the protocol was calculated to originally collect a minimum of 209 samples, and only 169 samples were collected, mostly from the lack of presence of the targeted areas, which can affect the power of the study. Another limitation is the fact that even though we knew the population of pigs housed in these barns was undergoing an outbreak we did not know the extent of viral shedding by the animals at the time of collection, which can play a role in environmental contamination.\u003c/p\u003e"},{"header":"Conclusions","content":"\u003cp\u003eIn summary, the detection of PRRSV genetic material on surfaces on the inside and outside areas of a farm housing PRRSV-positive pigs is possible using targeted surface sampling. This exploratory study provides evidence that biocontainment efforts to prevent the spread of PRRSV from infected farms are necessary.\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003e \u003cstrong\u003eEthics approval and consent to participate:\u003c/strong\u003e \u003cp\u003eNot applicable\u003c/p\u003e \u003c/p\u003e \u003cp\u003e \u003cstrong\u003eConsent for publication:\u003c/strong\u003e \u003cp\u003eNot applicable\u003c/p\u003e \u003c/p\u003e\u003cp\u003e \u003ch2\u003eCompeting interests:\u003c/h2\u003e \u003cp\u003eThe authors declare that they have no competing interests.\u003c/p\u003e \u003c/p\u003e\u003ch2\u003eFunding:\u003c/h2\u003e \u003cp\u003eThis project was funded by the University of Minnesota Swine Disease Eradication Center (SDEC).\u003c/p\u003e\u003ch2\u003eAuthor Contribution\u003c/h2\u003e\u003cp\u003eCMM: Writing \u0026ndash; original draft, Formal Analysis; MK: Writing \u0026ndash; review \u0026amp; editing; MT: Conceptualization, Funding acquisition, Writing \u0026ndash; review \u0026amp; editing; LB: Conceptualization, Writing - review \u0026amp; editing; CS: Writing - review \u0026amp; editing; BR: Writing - review \u0026amp; editing; PY: Conceptualization, Writing - review \u0026amp; editing; BL: Writing - review \u0026amp; editing; MA: Conceptualization, Writing - review \u0026amp; editing; KO: Writing - review \u0026amp; editing; MS: Writing - review \u0026amp; editing; CAC: Conceptualization, Funding acquisition, Writing \u0026ndash; review \u0026amp; editing. All authors reviewed the manuscript.\u003c/p\u003e\u003ch2\u003eAcknowledgments:\u003c/h2\u003e \u003cp\u003eThe authors would like to thank producers and swine veterinarians who participated in this study.\u003c/p\u003e\u003ch2\u003eAvailability of data and materials:\u003c/h2\u003e \u003cp\u003eThe dataset used and/or analyzed during the current study is available from the corresponding author upon reasonable request.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\u003cli\u003e\u003cspan\u003eHolck J, Polson D. The financial impact of PRRS virus. The porcine reproductive and respiratory syndrome compendium. 2nd ed. Des Moines, Iowa: National Pork Board; 2003.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eHoltkamp DJ, Kliebenstein JB, Neumann EJ. Assessment of the economic impact of porcine reproductive and respiratory syndrome virus on United States pork producers. 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An experimental model to evaluate the role of transport vehicles as a source of transmission of porcine reproductive and respiratory syndrome virus to susceptible pigs. Can J Vet Res. 2004;(68):128\u0026ndash;33.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eOtake S. Transmission of porcine reproductive and respiratory syndrome virus by fomites (boots and coveralls). J Swine Health Prod. 2002;10(2).\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eOtake S, Dee SA, Jacobson L, Torremorell M, Pijoan C. Evaluation of aerosol transmission of porcine reproductive and respiratory syndrome virus under controlled field conditions. Vet Rec. 2002;(150):804\u0026ndash;8.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003ePitkin A, Deen J, Dee S. Further assessment of fomites and personnel as vehicles for the mechanical transport and transmission of porcine reproductive and respiratory syndrome virus. Can J Vet Res. 2009;(73):298\u0026ndash;302.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eThompson M, Schulz-Dalquist L, Cano JP. Indirect transmission of PRRS virus in the farrowing rooms of a 6000-sow \u0026shy;herd. In: AASV Annual Meeting: Integrating Science, Welfare, and Economics in Practice. American Association of Swine Veterinarians; 2012. pp. 81\u0026ndash;2.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eThompson RW. Transmission of pathogens via transportation vehicles. In: 2001 Allen D Leman Swine Conference. Minnesota, USA: University of Minnesota; 2001.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eWills RW, Zimmerman JJ, Swenson SL, Yoon KJ, Hill HT, Bundy DS. Transmission of PRRSV by direct, close, or indirect contact. Swine Health Prod. 1997;5(6).\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eArruda AG, Tousignant S, Sanhueza J, Vilalta C, Poljak Z, Torremorell M, et al. Aerosol Detection and Transmission of Porcine Reproductive and Respiratory Syndrome Virus (PRRSV): What Is the Evidence, and What Are the Knowledge Gaps? Viruses. 2019;11(8):712.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eDee S, Otake S, Deen J. Use of a production region model to assess the efficacy of various air filtration systems for preventing airborne transmission of porcine reproductive and respiratory syndrome virus and Mycoplasma hyopneumoniae: Results from a 2-year study. Virus Res. 2010;154(1\u0026ndash;2):177\u0026ndash;84.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eKristensen CS, B\u0026oslash;tner A, Takai H, Nielsen JP, Jorsal SE. Experimental airborne transmission of PRRS virus. Vet Microbiol. 2004;99(3\u0026ndash;4):197\u0026ndash;202.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eOtake S, Dee SA, Jacobson L, Torremorell M, Pijoan C. 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An evaluation of ultraviolet light (UV254) as a means to inactivate porcine reproductive and respiratory syndrome virus on common farm surfaces and materials. Vet Microbiol. 2011;150(1\u0026ndash;2):96\u0026ndash;9.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eGarrido-Mantilla J, Alvarez J, Culhane M, Nirmala J, Cano JP, Torremorell M. Comparison of individual, group and environmental sampling strategies to conduct influenza surveillance in pigs. BMC Vet Res. 2019;15(1):61.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eVilalta C, Sanhueza J, Garrido J, Murray D, Morrison R, Corzo CA, et al. Indirect assessment of porcine reproductive and respiratory syndrome virus status in pigs prior to weaning by sampling sows and the environment. Vet Microbiol. 2019;237:108406.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eGreatorex JS, Digard P, Curran MD, Moynihan R, Wensley H, Wreghitt T et al. Survival of Influenza A(H1N1) on Materials Found in Households: Implications for Infection Control. Cowling BJ, editor. PLoS ONE. 2011;6(11):e27932.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eThomas PR, Karriker LA, Acvpm D, Ramirez A, Acvpm D, Zhang J et al. Evaluation of time and temperature sufficient to inactivate porcine epidemic diarrhea virus in swine feces on metal surfaces. J Swine Health Prod. 2015;23(2).\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eCutler TD, Wang C, Hoff SJ, Zimmerman JJ. Effect of temperature and relative humidity on ultraviolet (UV254) inactivation of airborne porcine respiratory and reproductive syndrome virus. Vet Microbiol. 2012;159(1\u0026ndash;2):47\u0026ndash;52.\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":"porcine-health-management","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"phmj","sideBox":"Learn more about [Porcine Health Management](http://porcinehealthmanagement.biomedcentral.com/)","snPcode":"40813","submissionUrl":"https://submission.nature.com/new-submission/40813/3","title":"Porcine Health Management","twitterHandle":"@animalplantsci","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"em","reportingPortfolio":"BMC/SO AJ","inReviewEnabled":true,"inReviewRevisionsEnabled":true},"keywords":"PRRS, environmental sampling, surfaces, contamination","lastPublishedDoi":"10.21203/rs.3.rs-4784873/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-4784873/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003ch2\u003eBackground\u003c/h2\u003e \u003cp\u003ePorcine reproductive and respiratory syndrome virus (PRRSV) can be transmitted indirectly between infected and susceptible pigs through the contamination of inanimate objects or aerosols. PRRSV can be present on surfaces for prolonged periods, and under certain conditions of temperature, humidity and type of surface, remain viable outside the host. In the United States, the yearly epidemic of PRRSV typically begins in the fall. During the fall of 2020, the variant L1C.5 emerged and rapidly spread throughout southern Minnesota, which generated questions regarding possible transmission routes. This study aimed to investigate whether PRRSV could be detected on surfaces inside and outside pig barns housing L1C.5 variant PRRSV-positive pigs to illustrate the potential for indirect transmission of PRRSV.\u003c/p\u003e\u003ch2\u003eResults\u003c/h2\u003e \u003cp\u003eAll (n\u0026thinsp;=\u0026thinsp;26) samples from PRRSV-negative farm tested negative. Nineteen (13%) out of 143 samples from positive farms yielded positive RT-PCR results. Positive samples originated primarily from exhaust fan cones and doorknobs, followed by anteroom floor and mortality carts/sleds. Virus isolation attempted on two samples did not yield positive results.\u003c/p\u003e\u003ch2\u003eConclusions\u003c/h2\u003e \u003cp\u003ePRRSV contamination can occur on surfaces inside and outside pig barns that are in frequent contact with farm personnel. Although virus isolation attempts were negative, our results illustrate the potential for PRRSV to be transmitted indirectly through contaminated materials or farm personnel. The study supports the implementation of biosecurity practices by farm personnel to prevent the introduction of PRRSV into farms and the prevention of PRRSV transmission between farms.\u003c/p\u003e","manuscriptTitle":"Assessment of porcine reproductive and respiratory syndrome virus (PRRSV) farm surface contamination through environmental sampling","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2024-08-16 21:03:08","doi":"10.21203/rs.3.rs-4784873/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"decision","content":"Revision requested","date":"2024-08-11T10:16:49+00:00","index":"","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2024-08-10T15:41:51+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"277263297575302362653437678715128343364","date":"2024-07-26T08:45:39+00:00","index":"hide","fulltext":""},{"type":"reviewersInvited","content":"","date":"2024-07-23T17:12:43+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2024-07-23T02:10:55+00:00","index":"","fulltext":""},{"type":"checksComplete","content":"","date":"2024-07-23T02:10:40+00:00","index":"","fulltext":""},{"type":"submitted","content":"Porcine Health Management","date":"2024-07-23T01:37:46+00:00","index":"","fulltext":""}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"porcine-health-management","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"phmj","sideBox":"Learn more about [Porcine Health Management](http://porcinehealthmanagement.biomedcentral.com/)","snPcode":"40813","submissionUrl":"https://submission.nature.com/new-submission/40813/3","title":"Porcine Health Management","twitterHandle":"@animalplantsci","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"em","reportingPortfolio":"BMC/SO AJ","inReviewEnabled":true,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"5cd876fc-c0eb-4f3c-8814-ad4a0105060d","owner":[],"postedDate":"August 16th, 2024","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"published-in-journal","subjectAreas":[],"tags":[],"updatedAt":"2024-09-30T16:11:15+00:00","versionOfRecord":{"articleIdentity":"rs-4784873","link":"https://doi.org/10.1186/s40813-024-00387-5","journal":{"identity":"porcine-health-management","isVorOnly":false,"title":"Porcine Health Management"},"publishedOn":"2024-09-27 15:58:00","publishedOnDateReadable":"September 27th, 2024"},"versionCreatedAt":"2024-08-16 21:03:08","video":"","vorDoi":"10.1186/s40813-024-00387-5","vorDoiUrl":"https://doi.org/10.1186/s40813-024-00387-5","workflowStages":[]},"version":"v1","identity":"rs-4784873","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-4784873","identity":"rs-4784873","version":["v1"]},"buildId":"qtupq5eGEP_6zYnWcrvyt","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}