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ORIGINAL RESEARCH article
Front. Vet. Sci.
Sec. One Health
Volume 12 - 2025 | doi: 10.3389/fvets.2025.1523981
This article is part of the Research Topic Emerging Zoonotic Diseases: Understanding and Mitigating Risks at Animal-Human Interfaces View all 3 articles
Estimating the Risk of Zoonotic Transmission of Swine Influenza A Variant During Agricultural Fairs in the United States: A Mathematical Modeling
Provisionally accepted- 1 College of Veterinary Medicine & Biomedical Sciences, Texas A&M University, College Station, United States
- 2 Department of Animal Science, College of Agriculture and Life Sciences, Texas A&M University College Station, College Station, Texas, United States
- 3 Department of Epidemiology & Biostatistics, School of Public Health, Texas A&M University College Station, College Station, Texas, United States
Introduction: Agricultural fairs offer a unique interface between humans and swine. We investigate the transmissibility of influenza A variant from pigs to humans using epidemiological data from a 2011 zoonotic outbreak of an influenza H3N2 variant during an agricultural county fair in Pennsylvania.Methods: We developed a mathematical model for the transmission of a swine influenza pathogen among pigs and humans at an agricultural fair. We fitted our model to the outbreak data to estimate zoonotic transmissibility. We considered nine data-driven scenarios of swine-to-swine basic reproductive number (R0) and the number of infected pigs at the start of the fair, and we simulated the zoonotic outbreak dynamics.Results: We estimated the probability of swine-to-human H3N2v transmission per minute of swine contact for which our model best fitted the data. The probability of transmission of H3N2v per minute of contact with swine among club members was estimated to vary from 0.029 (95% confidence interval (CI): 0.028 -0.030), when R0=2 with 1 initially infected pig, to 0.00099 (0.00095 -0.00102), when R0=6 with 5 initially infected pigs. For attendees, we showed that the probability equals 0.0168 (95% CI: 0.0167 -0.0169), when R0=2 with 1 initially infected pig, and 0.00371 (95% CI: 0.00368 -0.00373), when R0=2 with 5 initially infected pigs. For all scenarios, we estimated H3N2v infection prevalence among club members and attendees to average 12% and 0.7%, respectively.Discussion: These results show that the transmission risk may vary substantially between club members and attendees and with the underlying disease transmission among pigs. Although fair attendees may have a small transmissibility risk, annual fair attendees represent a large population likely to experience zoonotic events and facilitate the emergence of a potential pandemic influenza variant.
Keywords: Agricultural fair, Swine influenza, mathematical modeling, transmission risk, Zoonotic events
Received: 06 Nov 2024; Accepted: 06 Mar 2025.
Copyright: © 2025 Pittman Ratterree, Chitlapilly Dass and Ndeffo-Mbah. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) or licensor are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.
* Correspondence:
Martial Loth Ndeffo-Mbah, College of Veterinary Medicine & Biomedical Sciences, Texas A&M University, College Station, United States
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