Since 2011, there have been more confirmed human cases of swine flu in the U.S. than anywhere else in the world, according to the article linked here. Most have come from agricultural shows and fairs. Dr. Andrew Bowman, a molecular epidemiologist at The Ohio State University, and his colleagues have documented the dangers and looked for ways to make pig shows safer. He says what needs to change, “is an awful lot of human behavior.”
After the 2009 swine flu pandemic, Bowman, who was a practicing veterinarian, went back to Ohio State to work on a swine surveillance project. They uncovered a network of events that resulted in human infections in a predictable cycle. Jackpot shows, county and state fairs are perfect environments for pigs to shed influenza virus among themselves and humans.
By the end of the fair,” Dr. Bowman said, “you have 200 pigs shedding influenza virus.”
Source: The New York Times, July 25, 2023. Link. Spillover is not a rare event. In 2012, a major swine flu outbreak caused more than 300 confirmed human cases; Dr. Bowman and his colleagues found evidence that the virus has jumped from pigs to people during at least seven different Ohio fairs.”