SAN FRANCISCO — Researchers in the United States suggest that protective measures make good sense for both the animals and humans as the spread of influenza among pigs is common at fairs and other gatherings.
In a study that appeared in the journal Emerging Infectious Diseases, a publication of the US Centers for Disease Control and Prevention (CDC), the researchers tracked human cases of H3N2 swine virus associated with seven agricultural fairs in 2016.
Led by Andrew Bowman of The Ohio State University, they tallied 18 cases in Ohio and Michigan documented after exposure to flu-infected pigs.
Ways to curtail the spread of disease without eliminating swine exhibits altogether, according to Bowman, an assistant professor of veterinary medicine, includes cutting the length of time pigs and people congregate, as a 72-hour limit to swine exhibits is likely to interrupt widespread flu transmission from pig to pig and from pigs to people.
Other measures include vaccinating pigs against flu; posting guidance for handwashing and supplying hand sanitizer near animal exhibits; posting signs warning against eating and drinking around animal exhibits; encouraging those at higher risk of flu complications, such as babies, young children, adults over 65 and those with illnesses that weaken the immune system, to forego visits to the animal exhibits.
The study included 161 pigs at seven fairs, almost 78 percent of which tested positive for the virus, though in many cases there were no observable symptoms of flu, according to a news release from the university this week.
It was based on part of of a larger effort to monitor flu virus among exhibition swine at 101 fairs in the American Midwest, occupying the northern central part of the United States, where pigs were tested at the end of exhibitions regardless of clinical signs.
The researchers found genetically identical flu virus at multiple fairs in Ohio and Michigan, which illustrates how fast the virus can move within swine at agricultural shows. The H3N2 virus implicated in these pig-to-human transmissions didn’t originate in swine. In fact, people passed the virus to the pigs to begin with.
“As much as we like to point fingers at the pigs, it comes from us too,” Bowman was quoted as saying.