A researcher at The Ohio State University has been conducting a multi-state study testing for influenza viruses among pigs at county agricultural fairs.
Andrew Bowman, a veterinarian with Ohio State’s department of veterinary preventive medicine, has found that, on average, at one out of every four fairs he attends every year, at least one pig is infected with the influenza A virus infecting swine (IAV-S). Some of the infected pigs don’t show clinical signs of the illness when they’re tested.
The influenza A virus can infect pigs as well as other animals and people. When one case is discovered at a fair, more often than not, several cases are found at the same fair, Bowman said.
Bowman is little more than halfway through his seven-year study involving 100 county and state fairs in Ohio, Michigan and Indiana as well as a handful in Iowa, Kentucky and West Virginia.
Besides collecting nasal swab samples from 20 pigs at each fair, Bowman and his team also study what prevention measures are taken at the fairs and how often they are used to keep people and animals safe from flu.
In animals and people, the clinical signs of influenza can include fever, a runny nose, coughing and sometimes nausea. People previously infected with influenza from pigs generally report mild symptoms, much like seasonal flu. However, people most threatened by serious complications to influenza A virus infections are children under age five, older adults, pregnant women and individuals with weakened immune systems.
“People don’t tend to think these animals might have something or that people might have something they can give to the pigs. They think, ‘This is my chance to see a pig,’ and they go charging into the barns,” Bowman said.
In a 2012 study of 40 Ohio agricultural fairs, Bowman and his team found 10 pigs infected with H3N2, and at the majority of fairs with infected swine, people also caught the flu.
Agricultural fairs vary in prevention measures taken to keep people and pigs safe and in how well the public heeds the warnings, Bowman pointed out.
His staff watched people as they exited the pig barns and recorded whether they washed their hands. Most fairs in Bowman’s multi-state study provide hand washing stations outside the animal barns, but they were used by, on average, fewer than 10% of visitors, he said.
Bowman found that it’s not unusual for the people showing the pigs to sleep and eat in the barns with their animals, sometimes for several days, and these conditions make it easy for flu, if present, to spread among people and animals. Also, keeping pigs at a county fair for more than three days puts the pigs at greater risk of catching a flu because they mingle, so illnesses can spread quickly.
Bowman said it is tough to encourage people to change a longtime tradition of pigs staying at the fair for a week or people sleeping or eating in the barn with their animals. “It’s like trying to change the rotation of the Earth,” he said.
IAV-S infections may seem inconsequential to those who aren’t especially vulnerable, but whenever a flu transitions from infecting only animals to also infecting people, that can be problematic, Bowman said. Each time a new influenza A virus emerged and spread around the world to which most people do not have immunity, it came from animals.
One focus of Bowman’s research, he said, is to come up with scientific data so "we can make evidence-based decisions about how to have agricultural fairs in a way that’s safe and still fun, just by doing things a little differently.”
Every year, Bowman shares his test results with the participating fairs, as well as state and national animal and public health officials. His research is primarily funded through a contract with the St. Jude Center of Excellence for Influenza Research & Surveillance, with funds from the National Institute of Allergy & Infectious Diseases, part of the National Institutes of Health.
Bowman advises fair-goers to wash their hands after being in contact with animals, avoid eating, drinking or sleeping in the animal areas and refrain from taking toys, baby bottles, strollers or similar items into the barns.
Eating pork, as long it has been properly cooked, cannot cause someone to catch the influenza A virus.