Evolution of influenza A viruses in exhibition swine and transmission to humans, 2013-2015.

AIMS: Swine are a mixing vessel for the emergence of novel reassortant influenza A viruses (IAV). Interspecies transmission of swine-origin IAV poses a public health and pandemic risk. In the United States, the majority of zoonotic IAV transmission events have occurred in association with swine exposure at agricultural fairs. Accordingly, this human-animal interface necessitates mitigation strategies informed by understanding of interspecies transmission mechanisms in exhibition swine. Likewise, the diversity of IAV in swine can be a source for novel reassortant or mutated viruses that pose a risk to both swine and human health. METHODS AND RESULTS: In an effort to better understand those risks, here we investigated the epidemiology of IAV in exhibition swine and subsequent transmission to humans by performing phylogenetic analyses using full genome sequences from 272 IAV isolates collected from exhibition swine and 23 A(H3N2)v viruses from human hosts during 2013-2015. Sixty-seven fairs (24.2%) had at least one pig test positive for IAV with an overall estimated prevalence of 8.9% (95% CI: 8.3-9.6, Clopper-Pearson). Of the 19 genotypes found in swine, 5 were also identified in humans. There was a positive correlation between the number of human cases of a genotype and its prevalence in exhibition swine. Additionally, we demonstrated that A(H3N2)v viruses clustered tightly with exhibition swine viruses that were prevalent in the same year. CONCLUSIONS: These data indicate that multiple genotypes of swine-lineage IAV have infected humans, and highly prevalent IAV genotypes in exhibition swine during a given year are also the strains detected most frequently in human cases of variant IAV. Continued surveillance and rapid characterization of IAVs in exhibition swine can facilitate timely phenotypic evaluation and matching of candidate vaccine strains to those viruses present at the human-animal interface which are most likely to spillover into humans.

Sampling and recovery of infectious SARS-CoV-2 from high-touch surfaces by sponge stick and macrofoam swab.

Effective sampling for severe acute respiratory syndrome 2 (SARS-CoV-2) is a common approach for monitoring disinfection efficacy and effective environmental surveillance. This study evaluated sampling efficiency and limits of detection (LODs) of macrofoam swab and sponge stick sampling methods for recovering infectious SARS-CoV-2 and viral RNA (vRNA) from surfaces. Macrofoam swab and sponge stick methods were evaluated for collection of SARS-CoV-2 suspended in a soil load from 6-in2 coupons composed of four materials: stainless steel (SS), acrylonitrile butadiene styrene (ABS) plastic, bus seat fabric, and Formica. Recovery of infectious SARS-CoV-2 was more efficient than vRNA recovery on all materials except Formica (macrofoam swab sampling) and ABS (sponge stick sampling). Macrofoam swab sampling recovered significantly more vRNA from Formica than ABS and SS, and sponge stick sampling recovered significantly more vRNA from ABS than Formica and SS, suggesting that material and sampling method choice can affect surveillance results. Time since initial contamination significantly affected infectious virus recovery from all materials, with vRNA recovery showing limited to no difference, suggesting that SARS-CoV-2 vRNA can remain detectable after viral infectivity has dissipated. This study showed that a complex relationship exists between sampling method, material, time from contamination to sampling, and recovery of SARS-CoV-2. In conclusion, data show that careful consideration be used when selecting surface types for sampling and interpreting SARS-CoV-2 vRNA recovery with respect to presence of infectious virus.

Shortening Duration of Swine Exhibitions to Reduce Risk for Zoonotic Transmission of Influenza A Virus.

Reducing zoonotic influenza A virus (IAV) risk in the United States necessitates mitigation of IAV in exhibition swine. We evaluated the effectiveness of shortening swine exhibitions to <72 hours to reduce IAV risk. We longitudinally sampled every pig daily for the full duration of 16 county fairs during 2014-2015 (39,768 nasal wipes from 6,768 pigs). In addition, we estimated IAV prevalence at 195 fairs during 2018-2019 to test the hypothesis that <72-hour swine exhibitions would have lower IAV prevalence. In both studies, we found that shortening duration drastically reduces IAV prevalence in exhibition swine at county fairs. Reduction of viral load in the barn within a county fair is critical to reduce the risk for interspecies IAV transmission and pandemic potential. Therefore, we encourage fair organizers to shorten swine shows to protect the health of both animals and humans.

Residual antimicrobial coating efficacy against SARS-CoV-2.

AIMS: This study evaluated the residual efficacy of commercially available antimicrobial coatings or films against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) on non-porous surfaces. METHODS AND RESULTS: Products were applied to stainless steel or ABS plastic coupons and dried overnight. Coupons were inoculated with SARS-CoV-2 in the presence of 5% soil load. Recovered infectious SARS-CoV-2 was quantified by TCID50 assay. Tested product efficacies ranged from <1.0 to >3.0 log10 reduction at a 2-h contact time. The log10 reduction in recovered infectious SARS-CoV-2 ranged from 0.44 to 3 log10 reduction on stainless steel and 0.25 to >1.67 log10 on ABS plastic. The most effective products tested contained varying concentrations (0.5%-1.3%) of the same active ingredient: 3-(trihydroxysilyl) propyldimethyloctadecyl ammonium chloride. Products formulated with other quaternary ammonium compounds were less effective against SARS-CoV-2 in this test. CONCLUSIONS: The residual antimicrobial products tested showed varied effectiveness against SARS-CoV-2 as a function of product tested. Several products were identified as efficacious against SARS-CoV-2 on both stainless steel and ABS plastic surfaces under the conditions evaluated. Differences in observed efficacy may be due to variation in active ingredient formulation; efficacy is, therefore, difficult to predict based upon listed active ingredient and its concentration. SIGNIFICANCE AND IMPACT: This study highlights the formulation-specific efficacy of several products against SARS-CoV-2 and may inform future development of residual antiviral products for use on non-porous surfaces. The identification of antimicrobial coatings or films showing promise to inactivate SARS-CoV-2 suggests that these products may be worth future testing and consideration.

Efficacy of detergent-based cleaning methods against coronavirus MHV-A59 on porous and non-porous surfaces.

This study evaluated the efficacy of detergent-based surface cleaning methods against Murine Hepatitis Virus A59 (MHV) as a surrogate coronavirus for SARS-CoV-2. MHV (5% soil load in culture medium or simulated saliva) was inoculated onto four different high-touch materials [stainless steel (SS), Acrylonitrile Butadiene Styrene plastic (ABS), Formica, seat fabric (SF)]. Immediately and 2-hr post-inoculation, coupons were cleaned (damp wipe wiping) with and without pretreatment with detergent solution or 375 ppm hard water. Results identified that physical removal (no pretreatment) removed >2.3 log10 MHV on ABS, SS, and Formica when surfaces were cleaned immediately. Pretreatment with detergent or hard water increased effectiveness over wet wiping 2-hr post-inoculation; pretreatment with detergent significantly increased (p ≤ 0.05) removal of MHV in simulated saliva, but not in culture media, over hard water pretreatment (Formica and ABS). Detergent and hard water cleaning methods were ineffective on SF under all conditions. Overall, efficacy of cleaning methods against coronaviruses are material- and matrix-dependent; pre-wetting surfaces with detergent solutions increased efficacy against coronavirus suspended in simulated saliva. This study provides data highlighting the importance of incorporating a pre-wetting step prior to detergent cleaning and can inform cleaning strategies to reducing coronavirus surface transmission.

Efficacy of chemical disinfectants against SARS-CoV-2 on high-touch surface materials.

AIMS: This study aimed to provide operationally relevant severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) surface disinfection efficacy information. METHODS AND RESULTS: Three EPA-registered disinfectants (Vital Oxide, Peroxide, and Clorox Total 360) and one antimicrobial formulation (CDC bleach) were evaluated against SARS-CoV-2 on material coupons and were tested using Spray (no touch with contact time) and Spray & Wipe (wipe immediately post-application) methods immediately and 2 h post-contamination. Efficacy was evaluated for infectious virus, with a subset tested for viral RNA (vRNA) recovery. Efficacy varied by method, disinfectant, and material. CDC bleach solution showed low efficacy against SARS-CoV-2 (log reduction < 1.7), unless applied via Spray & Wipe. Additionally, mechanical wiping increased the efficacy of treatments against SARS-CoV-2. The recovery of vRNA post-disinfection suggested that vRNA may overestimate infectious virus remaining. CONCLUSIONS: Efficacy depends on surface material, chemical, and disinfection procedure, and suggests that mechanical wiping alone has some efficacy at removing SARS-CoV-2 from surfaces. We observed that disinfectant treatment biased the recovery of vRNA over infectious virus. SIGNIFICANCE AND IMPACT OF STUDY: These data are useful for developing effective, real-world disinfection procedures, and inform public health experts on the utility of PCR-based surveillance approaches.

Influenza Vaccination of Swine Reduces Public Health Risk at the Swine-Human Interface.

Influenza A viruses (IAV) in swine (IAV-S) pose serious risk to public health through spillover at the human-animal interface. Continued zoonotic transmission increases the likelihood novel IAV-S capable of causing the next influenza pandemic will emerge from this animal reservoir. Because current mitigation strategies are insufficient to prevent IAV zoonosis, we investigated the ability of swine vaccination to decrease IAV-S zoonotic transmission risk. We assessed postchallenge viral shedding in market-age swine vaccinated with either live-attenuated influenza virus (LAIV), killed influenza virus (KV), or sham vaccine (NV). We also assessed postchallenge transmission by exposing naive ferrets to pigs with contact types reflective of those experienced by humans in a field setting. LAIV and KV swine groups exhibited a nearly 100-fold reduction in peak nasal titer (LAIV mean, 4.55 log 50% tissue culture infectious dose [TCID50]/ml; KV mean, 4.53 log TCID50/ml) compared to NV swine (mean, 6.40 log TCID50/ml). Air sampling during the postchallenge period revealed decreased cumulative IAV in LAIV and KV study room air (LAIV, area under the concentration-time curve [AUC] of 57.55; KV, AUC = 24.29) compared to the NV study room (AUC = 86.92). Pairwise survival analysis revealed a significant delay in onset of infection among ferrets exposed to LAIV pigs versus NV pigs (rate ratio, 0.66; P = 0.028). Ferrets exposed to vaccinated pigs had lower cumulative virus titers in nasal wash samples (LAIV versus NV, P < 0.0001; KV versus NV, P= 0.3490) and experienced reduced clinical signs during infection. Our findings support the implementation of preexhibition influenza vaccination of swine to reduce the public health risk posed by IAV-S at agricultural exhibitions. IMPORTANCE Swine exhibited at agricultural fairs in North America have been the source of repeated zoonotic influenza A virus transmission, which creates a pathway for influenza pandemic emergence. We investigated the effect of using either live-attenuated influenza virus or killed influenza virus vaccines as prefair influenza vaccination of swine on zoonotic influenza transmission risk. Ferrets were exposed to the pigs in order to simulate human exposure in a field setting. We observed reductions in influenza A virus shedding in both groups of vaccinated pigs as well as the corresponding ferret exposure groups, indicating vaccination improved outcomes on both sides of the interface. There was also significant delay in onset of infection among ferrets that were exposed to live-attenuated virus-vaccinated pigs, which might be beneficial during longer fairs. Our findings indicate that policies mandating influenza vaccination of swine before fairs, while not currently common, would reduce the public health risk posed by influenza zoonosis.

Adoption of recommended hand hygiene practices to limit zoonotic disease transmission at agricultural fairs.

Rapid transmission and spread of infectious pathogens are enhanced by the agricultural fair environment, where large numbers of livestock and people from numerous backgrounds congregate for several days. The transmission of influenza A virus and zoonotic enteric pathogens to fairgoers is a considerable risk and has occurred several times over the past decade. In an effort to mitigate zoonotic disease transmission in these settings, public health guidelines and recommendations including hand sanitation stations have been implemented. While hand hygiene recommendations to prevent the spread of zoonotic disease are well communicated, it is hypothesized that the adoption of these recommendations by agricultural fairs and fairgoers is low. To test this hypothesis, hand hygiene data collected from 658 agricultural fairs between 2012 and 2019 was analyzed to determine frequency and function of hand sanitation stations at the fairs, as well as utilization of educational signage. In addition, an observational study was performed to calculate the proportion of fairgoers who use hand sanitation stations at the fair. Lastly, samples were taken from working hand sanitation stations present at the exits of livestock barns and tested for the presence of influenza A virus and antimicrobial resistant coliform bacteria. Hand sanitation stations were present at most fairs (77.4 %) as recommended, but only 142 out of 2021 (7.0 %) visitors were observed using the stations. Health risk signage was displayed at more than half of fairs while the proper wash procedure was displayed at less than half. No influenza A virus was detected on any of the hand sanitation stations, however antimicrobial resistant coliform bacteria were recovered from 75.5 % of the sampled hand sanitation stations. Fairs should employ educational material along with functional hand sanitation stations in order to promote hand hygiene at fairs. Stations should be maintained and cleaned often to ensure effectiveness, as hand hygiene continues to be recommended to fairgoers when exiting animal barns to reduce zoonotic disease transmission.

Assessing exhibition swine as potential disseminators of infectious disease through the detection of five respiratory pathogens at agricultural exhibitions.

Widespread geographic movement and extensive comingling of exhibition swine facilitates the spread and transmission of infectious pathogens. Nasal samples were collected from 2862 pigs at 102 exhibitions and tested for five pathogens. At least one pathogen was molecularly detected in pigs at 63 (61.8%) exhibitions. Influenza A virus was most prevalent and was detected in 498 (17.4%) samples. Influenza D virus was detected in two (0.07%) samples. More than one pathogen was detected in 165 (5.8%) samples. Influenza A virus remains a top threat to animal and human health, but other pathogens may be disseminated through the exhibition swine population.

Madin-Darby canine kidney cell sialic acid receptor modulation induced by culture medium conditions: Implications for the isolation of influenza A virus.

BACKGROUND: The influenza A virus (IAV) binds to α-2,3- and α-2,6-linked sialic acid (SA) receptors expressed by Madin-Darby canine kidney (MDCK) cells. The receptor distribution may therefore be important in regulating IAV propagation. Serum-free medium (SFM) avoids variability in conventional culture medium containing fetal bovine serum (FBS), which can have variable composition and may contain endotoxins. However, little is known about the distribution of SA receptors on cells maintained in SFM. OBJECTIVES: We assessed the influence of culture media on MDCK cell SA receptor distribution along with the effect of SA receptor distribution on IAV recovery. We hypothesized that SFM would increase the proportion of α-2,6-linked SA receptors present and alter isolate recovery. METHODS: Madin-Darby canine kidney cells were cultured in medium containing FBS and two SFMs. Cell surface distribution of α-2,6- and α-2,3-linked receptors was determined using flow cytometry. Recovery of swine- and avian-lineage IAVs from MDCK cells maintained in each medium was quantified as TCID50 . RESULTS: Madin-Darby canine kidney cells cultured in UltraMDCK SFM expressed both SA receptors and supported the growth of both swine- and avian-lineage IAVs. Cells maintained in other medium inconsistently expressed each receptor and the avian IAV grew to lower titers in cells cultured with FBS. CONCLUSIONS: Medium conditions altered the distribution of SA receptors present on MDCK cells and affected IAV recovery. Culture in UltraMDCK SFM resulted in cells expressing both receptors and IAVs grew to higher titers than in the other culture condition, indicating that this medium may be useful for culturing IAV from multiple species.

Complete Genome Sequence of an Influenza D Virus Strain Identified in a Pig with Subclinical Infection in the United States.

Influenza D virus was first described in 2011 from a pig with respiratory disease; however, recent evidence indicates that cattle are the major viral reservoir. Here, we describe the genome sequence of the eighth complete swine-origin influenza D virus deposited into GenBank, D/swine/Kentucky/17TOSU1262/2017, which was collected at a 2017 swine exhibition.

Porcine Epidemic Diarrhea Virus and Porcine Deltacoronavirus not Detected in Waterfowl in the North American Mississippi Migratory Bird Flyway in 2013.

Cloacal swab samples collected from 538 migratory waterfowl along the Mississippi Migratory Bird Flyway in 2013 were tested for porcine epidemic diarrhea virus and porcine deltacoronavirus. Neither virus was detected in any of the samples, indicating that waterfowl likely did not contribute to the rapid spread of these viruses within central US.

Evaluation of nonwoven fabrics for nasal wipe sampling for influenza A virus in swine.

Influenza A virus (IAV) is a zoonotic pathogen threatening animal and public health; therefore, detection and monitoring of IAV in animal populations are critical components of a surveillance program. Swine are important hosts of IAV, wherein the virus can undergo rapid evolution. Several methods (i.e., nasal swabs, nasal wipes, and oral fluids) have been used to collect samples from swine for IAV surveillance. We utilized nasal wipes made from cotton gauze and multiple, polyester or mixed polyester fabrics to compare performance in the molecular detection and isolation of IAV. In vitro experiments revealed that no polyester or mixed polyester fabric was superior to cotton gauze for molecular IAV detection; however, 3 polyester or mixed polyester fabrics yielded significantly more viable IAV than cotton. In a field trial, both cotton gauze and the polyester or mixed polyester fabric yielded similar proportions of IAV isolates from swine. The results indicate that cotton gauze remains a practical and useful material for swine nasal wipes.

Detection of influenza A virus from agricultural fair environment: Air and surfaces.

Agricultural fairs facilitate an environment conducive to the spread of influenza A virus with large numbers of pigs from various different locales comingling for several days (5-8 days). Fairs are also associated with zoonotic transmission of influenza A virus as humans have unrestricted contact with potentially infected swine throughout the fair's duration. Since 2005, the Centers for Disease Control and Prevention has reported 468 cases of variant influenza A virus, with most cases having had exposure to swine at agricultural fairs. Many mechanisms have been proposed as potential direct and indirect routes of transmission that may be enhancing intra- and inter-species transmission of influenza A virus at fairs. This study examines airborne respiratory droplets and portable animal-care items as potential routes of transmission that may be contributing to enhanced viral spread throughout the swine barn and the resulting variant cases of influenza A. Air samples were taken from inside swine barns at 25 fairs between the years 2013 and 2014. Influenza A virus was detected molecularly in 11 of 59 (18.6%) air samples, representing 4 of the 25 fairs. Viable H1N1 virus, matching virus recovered from swine at the fair, was recovered from the air at one fair in 2013. During the summer of 2016, 75 of 400 (18.8%) surface samples tested positive for molecular presence of influenza A virus and represented 10 of 20 fairs. Seven viral isolates collected from four fairs were recovered from the surfaces. Whole genome sequences of the viruses recovered from the surfaces are >99% identical to the viruses recovered from individual pigs at each respective fair. The detection and recovery of influenza A virus from both the air and surfaces found within the swine barn at agricultural fairs provide evidence for potential viral transmission through these routes, which may contribute to both intra- and inter-species transmission, threatening public health. These findings reinforce the need for new and improved mitigation strategies at agricultural fairs in order to reduce the risk to animal and public health.

Introduction, Evolution, and Dissemination of Influenza A Viruses in Exhibition Swine in the United States during 2009 to 2013.

The swine-human interface created at agricultural fairs, along with the generation of and maintenance of influenza A virus diversity in exhibition swine, presents an ongoing threat to public health. Nucleotide sequences of influenza A virus isolates collected from exhibition swine in Ohio (n = 262) and Indiana (n = 103) during 2009 to 2013 were used to investigate viral evolution and movement within this niche sector of the swine industry. Phylogenetic and Bayesian analyses were employed to identify introductions of influenza A virus to exhibition swine and study viral population dynamics. In 2013 alone, we identified 10 independent introductions of influenza A virus into Ohio and/or Indiana exhibition swine. Frequently, viruses from the same introduction were identified at multiple fairs within the region, providing evidence of rapid and widespread viral movement within the exhibition swine populations of the two states. While pigs moving from fair to fair to fair is possible in some locations, the concurrent detection of nearly identical strains at several fairs indicates that a common viral source was more likely. Importantly, we detected an association between the high number of human variant H3N2 (H3N2v) virus infections in 2012 and the widespread circulation of influenza A viruses of the same genotype in exhibition swine in Ohio fairs sampled that year. The extent of viral diversity observed in exhibition swine and the rapidity with which it disseminated across long distances indicate that novel strains of influenza A virus will continue to emerge and spread within exhibition swine populations, presenting an ongoing threat to humans. IMPORTANCE: Understanding the underlying population dynamics of influenza A viruses in commercial and exhibition swine is central to assessing the risk for human infections with variant viruses, including H3N2v. We used viral genomic sequences from isolates collected from exhibition swine during 2009 to 2013 to understand how the peak of H3N2v cases in 2012 relates to long-term trends in the population dynamics of pandemic viruses recently introduced into commercial and exhibition swine in the United States. The results of our spatial analysis underscore the key role of rapid viral dispersal in spreading multiple genetic lineages throughout a multistate network of agricultural fairs, providing opportunities for divergent lineages to coinfect, reassort, and generate new viral genotypes. The higher genetic diversity of genotypes cocirculating in exhibition swine since 2013 could facilitate the evolution of new reassortants, potentially with even greater ability to cause severe infections in humans or cause human-to-human transmission, highlighting the need for continued vigilance.

Inactivation of porcine epidemic diarrhea virus using heated water.

Porcine epidemic diarrhea virus (PEDV) is a very contagious swine pathogen that spreads easily via the fecal-oral route, notably from contaminated fomites. The present study investigated heated water as a method for rapid thermal inactivation of PEDV. Cell-culture adapted PEDV was treated with water at varying temperatures and viral titers were measured at multiple time points post-treatment. Viable PEDV was not recovered after a ten second or longer treatment with water heated to ≥76 °C; however, PEDV nucleic acid was detected in all samples regardless of treatment. Hot water decontamination could be considered in settings where chemical disinfection is impractical.

Nasal Wipes for Influenza A Virus Detection and Isolation from Swine.

Surveillance for influenza A viruses in swine is critical to human and animal health because influenza A virus rapidly evolves in swine populations and new strains are continually emerging. Swine are able to be infected by diverse lineages of influenza A virus making them important hosts for the emergence and maintenance of novel influenza A virus strains. Sampling pigs in diverse settings such as commercial swine farms, agricultural fairs, and live animal markets is important to provide a comprehensive view of currently circulating IAV strains. The current gold-standard ante-mortem sampling technique (i.e. collection of nasal swabs) is labor intensive because it requires physical restraint of the pigs. Nasal wipes involve rubbing a piece of fabric across the snout of the pig with minimal to no restraint of the animal. The nasal wipe procedure is simple to perform and does not require personnel with professional veterinary or animal handling training. While slightly less sensitive than nasal swabs, virus detection and isolation rates are adequate to make nasal wipes a viable alternative for sampling individual pigs when low stress sampling methods are required. The proceeding protocol outlines the steps needed to collect a viable nasal wipe from an individual pig.

Effects of disinfection on the molecular detection of porcine epidemic diarrhea virus.

Routine detection of porcine epidemic diarrhea virus (PEDV) is currently limited to RT-PCR but this test cannot distinguish between viable and inactivated virus. We evaluated the capability of disinfectants to both inactivate PEDV and sufficiently damage viral RNA beyond RT-PCR detection. Five classes of disinfectants (phenol, quaternary ammonium compound, sodium hypochlorite, oxidizing agent, and quaternary ammonium/glutaraldehyde combination) were evaluated in vitro at varying concentrations, both in the presence and absence of swine feces, and at three different temperatures. No infectious PEDV was recovered after treatment with evaluated disinfectants. Additionally, all tested disinfectants except for 0.17% sodium hypochlorite dramatically reduced qRT-PCR values. However, no disinfectants eliminated RT-PCR detection of PEDV across all replicates; although, 0.52%, 1.03% and 2.06% solutions of sodium hypochlorite and 0.5% oxidizing agent did intermittently produce RT-PCR negatives. To simulate field conditions in a second aim, PEDV was applied to pitted aluminum coupons, which were then treated with either 2.06% sodium hypochlorite or 0.5% oxidizing agent. Post-treatment surface swabs of the coupons tested RT-PCR positive but were not infectious to cultured cells or naïve pigs. Ultimately, viable PEDV was not detected following application of each of the tested disinfectants, however in most cases RT-PCR detection of viral RNA remained. RT-PCR detection of PEDV is likely even after disinfection with many commercially available disinfectants.

Swine-to-human transmission of influenza A(H3N2) virus at agricultural fairs, Ohio, USA, 2012.

Agricultural fairs provide an opportunity for bidirectional transmission of influenza A viruses. We sought to determine influenza A virus activity among swine at fairs in the United States. As part of an ongoing active influenza A virus surveillance project, nasal swab samples were collected from exhibition swine at 40 selected Ohio agricultural fairs during 2012. Influenza A(H3N2) virus was isolated from swine at 10 of the fairs. According to a concurrent public health investigation, 7 of the 10 fairs were epidemiologically linked to confirmed human infections with influenza A(H3N2) variant virus. Comparison of genome sequences of the subtype H3N2 isolates recovered from humans and swine from each fair revealed nucleotide identities of >99.7%, confirming zoonotic transmission between swine and humans. All influenza A(H3N2) viruses isolated in this study, regardless of host species or fair, were >99.5% identical, indicating that 1 virus strain was widely circulating among exhibition swine in Ohio during 2012.