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ARS Home » Midwest Area » Ames, Iowa » National Animal Disease Center » Virus and Prion Research » Research » Publications at this Location » Publication #420022
Research Project: Intervention Strategies to Control Endemic and New and Emerging Influenza A Virus Infections in Swine

Location: Virus and Prion Research

Title: Influenza A virus detection at the human-swine interface in US Midwest swine farms

Author
item MORAES, DANIEL - Iowa State University
item ZELLER, MICHAEL - Iowa State University
item THOMAS, MEGAN - Iowa State University
item Anderson, Tavis
item LINHARES, DANIEL - Iowa State University
item Baker, Amy
item SILVA, GUSTAVO - Iowa State University
item GAUGER, PHILLIP - Iowa State University

Submitted to: Viruses
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/12/2024
Publication Date: 12/15/2024
Citation: Moraes, D.C., Zeller, M.A., Thomas, M.N., Anderson, T.K., Linhares, D.C., Baker, A.L., Silva, G.S., Gauger, P.C. 2024. Influenza A virus detection at the human-swine interface in US Midwest swine farms. Viruses. https://doi.org/10.3390/v16121921.
DOI: https://doi.org/10.3390/v16121921

Interpretive Summary: Influenza A virus (IAV) is a respiratory pathogen affecting swine worldwide and is a public health concern since IAV can be shared between humans and pigs. However, details are lacking on how and when IAV are transmitted between humans and swine in commercial farm settings. This study evaluated IAV detection and genetic diversity over time, specifically at the human-swine interface in swine breeding and nursery farms. The results showed higher positivity of IAV RNA detection in nursery pigs compared to pre-wean pigs, and more whole genome sequences were also obtained in the nursery phase. Surveillance of farm employees revealed 2 detections of H3N2 representing the 2022-23 human influenza season, suggesting swine may be at risk of exposure to human influenza strains from farm employees. This study highlights the importance of routine active surveillance to understand the dynamics of IAV at the farm level to effectively mitigate potential risks of bidirectional transmission and infection.

Technical Abstract: This study evaluated IAV detection and genetic diversity over time, specifically at the hu-man-swine interface in breeding and nursery farms. Active surveillance was performed monthly in five swine farms in the Midwest United States targeting the employees, the prewean piglets at sow farms, and the same cohort of piglets in downstream nurseries. In addition, information was collected at enrollment for each employee and farm to assess production management practices, IAV vaccination status, diagnostic procedures, and biosecurity. Farm employee and swine sam-ples were screened by IAV reverse transcription real-time polymerase chain reaction (RT-rtPCR), followed by IAV subtyping RT-rtPCR and whole genome sequencing on PCR-positive samples. This study showed higher positivity of IAV RNA detection in nursery pigs compared to prewean pigs, and more whole genome sequences were also obtained in the nursery phase. Surveillance of farm employees revealed 2 detections of H3N2 representing the 2022-23 human IAV season, sug-gesting swine may be at risk of exposure to human influenza strains from farm employees. This study highlights the importance of routine active surveillance to understand the dynamics of IAV at the farm level to mitigate potential risks of bidirectional transmission and infection effectively.