Influenza: A "fair-weather" foe

‘Tis the season for flu at state and county fairs, where the combination of masses of fairgoers, livestock exhibitors and hundreds of exhibition pigs creates an atmosphere ripe for influenza transmission from animals to humans – and in the opposite direction as well.

Last year, more than 300 U.S. human swine influenza cases were linked to 37 fairs in at least 10 states, and 16 people were hospitalized. In Ohio, 107 human cases were traced to 14 county fairs, and one person died.

People most at risk for complications if they are infected with influenza are children under 5 or adults over age 65, pregnant women in their last trimester and anyone with a compromised immune system. Avoiding or minimizing time spent in the pig barns at fairs is the safest bet for these at-risk populations, said Andrew Bowman, assistant professor of veterinary preventive medicine at The Ohio State University.

To better understand the dynamics of influenza transmission in pigs during fairs, Dr. Andy Bowman, assistant professor in the Department of Veterinary Preventive Medicine, and colleagues in the Animal Influenza Ecology and Epidemiology Research Program, are conducting an influenza surveillance project. This research project, funded by the Minnesota Center of Excellence for Influenza Research & Surveillance (MCEIRS) with federal funds from NIH, began in the summer of 2009 focusing on the One Health concept of bi-directional disease transmission from swine to humans, and from humans to swine at agricultural fairs in Ohio. They believed that if you commingle pigs and people for an extended period of time, as happens at fairs, influenza infections might occur and potentially spread among the pigs and/or people. Emily Caldwell, assistant director of research and innovation communications, offers details in her story, “A Fair-Weather Outbreak.” 

During the past four years, the research team collected nasal swabs from pigs at the end of the fair. This end-of-fair sampling provided critical information about the flu activity that was occurring in the pigs by the conclusion of the fair, but it left gaps in knowledge about the influenza transmission happening during the fair. The collection of nasal swabs requires restraint of the pig, thus making it unfeasible to collect nasal swabs from pigs during the exhibition. In order to overcome this obstacle, the members of the research team are investigating the use of snout wipes to conduct influenza A virus surveillance in pigs. If snout wipes are successful, there will be a way to test pigs during the fair without causing a disruption in events or create concern among owners. Collaboration wit the, Ohio Department of Agriculture, Indiana Board of Animal Health, Purdue Extension, and several fairs in Ohio and Indiana has allowed the research team to deploy the snout wiping method in the field during the summer and begin gaining a better understanding of influenza transmission dynamics of during fairs.

To demonstrate wiping pig snouts for influenza virus testing, the research team created an informational how-to video with simple steps to follow.