Influenza A(H3N2) Virus in Swine at Agricultural Fairs and Transmission to Humans, Michigan and Ohio, USA, 2016

Andrew S. Bowman; Rasna R. Walia; Jacqueline M. Nolting; Amy L. Vincent; Mary Lea Killian; Michele M. Zentkovich; Joshua N. Lorbach; Sarah E. Lauterbach; Tavis K. Anderson; C. Todd Davis; Natosha Zanders; Joyce Jones; Yunho Jang; Brian Lynch; Marisela R. Rodriguez; Lenee Blanton; Stephen E. Lindstrom; David E. Wentworth; John Schiltz; James J. Averill; Tony Forshey


Emerging Infectious Diseases. 2017;23(9):1551-1555. 

In This Article

Abstract and Introduction


In 2016, a total of 18 human infections with influenza A(H3N2) virus occurred after exposure to influenza-infected swine at 7 agricultural fairs. Sixteen of these cases were the result of infection by a reassorted virus with increasing prevalence among US swine containing a hemagglutinin gene from 2010–11 human seasonal H3N2 strains.


Influenza A virus infects many animal species. Zoonotic transmission allows for the introduction of novel influenza A virus strains to the human population, which has the potential to cause the next influenza pandemic. Swine exhibitions at agricultural fairs have emerged as a source for amplification of swine-lineage influenza A virus; these unique swine–human interfaces have generated most human infections with variant influenza A virus in the United States.[1]

During July–August 2016, outbreaks of variant H3N2 virus (H3N2v) were reported in Ohio and Michigan, and 18 zoonotic influenza A virus infections were detected.[2] All persons identified with H3N2v infections during these outbreaks reported swine exposure while attending >1 of 7 fairs in Ohio or Michigan. We examined the role of exhibition swine in the transmission of this reassortant influenza A virus, which contained a hemagglutinin gene from 2010–11 human seasonal H3N2 strains.