It was showtime at the youth swine exhibition, and the pig barn was bustling. The competitors, ages 3 to 21, were practicing their walks for the show ring and brushing pig bristles into place. Parents were braiding children’s hair, adding ribbons and pig-shaped barrettes.
Dr. Andrew Bowman, a molecular epidemiologist at Ohio State University, was striding through the barn in waterproof green overalls, searching for swine snot. As he slipped into one pen, a pig tried to nose its way out, then started nibbling his shoelaces.
Dr. Bowman prefers not to enter the pens, he said, as he wiped gauze across the animal’s nose. He soon spotted a more appealing subject: a pig sticking its nose out from between the bars of its enclosure. “We have a total bias for snouts out,” he said. Later, back in the lab, Dr. Bowman and his colleagues would discover that several of the snouts snuffling around this busy barn in New Lexington, Ohio, were harboring influenza.
The world is emerging from a pandemic that killed at least 6.9 million people. It won’t be the last. Outbreaks of zoonotic diseases, which can spread between animals and humans, have become more frequent in recent decades, and animal pathogens will continue spilling over into human populations in the years ahead. To Americans, spillover might seem like a distant problem, a danger that dwells in places like the live animal market in Wuhan, China, that may have been the origin of the Covid-19 pandemic.
“I think there’s this real feeling here in the U.S. that disease is something that comes from elsewhere,” said Ann Linder, an associate director at the animal law and policy program at Harvard Law School.
But there is real risk in our own backyards — and barnyards. Since 2011, there have been more confirmed human cases of swine flu in the United States than anywhere else in the world. (That may be because other nations are doing less testing and surveillance, and many cases here and abroad are likely to go undetected, experts say.) Most have been linked to agricultural shows and fairs. “They have become kind of hot spots,” Ms. Linder said.
Although flu is often mild in pigs, the animals are renowned for giving rise to novel flu variants. In 2009, one of these new variants, which originated in pigs in Mexico, set off a pandemic that killed at least 150,000 people, according to estimates from the Centers for Disease Control and Prevention.
“Lots of folks say, ‘Well, it’s just flu, what’s the big deal?’” Dr. Bowman said. “If it’s the next pandemic, then it’s really bad.”
For more than a decade, Dr. Bowman and his colleagues have been documenting the dangers and seeking ways to make swine shows safer. Meaningfully reducing the risks will require looking past the pigs to creatures on the other side of the spillover equation. What needs to change, Dr. Bowman said, “is an awful lot of human behavior.”
Pig pathogens
Pigs play a key role in the evolution of influenza. They can be infected by swine, bird and human flu viruses simultaneously, serving as mixing vessels in which different strains can reshuffle their genetic material, yielding new versions of the virus.
When the 2009 swine flu pandemic hit, influenza surveillance in pigs was limited, said Dr. Bowman, who was then a practicing veterinarian. But the outbreak was eye-opening, and Dr. Bowman, who attended veterinary school at Ohio State, returned to the university to work with one of his former professors on a swine surveillance project.
They began swabbing pigs at swine shows, ultimately uncovering a national network of events that resulted in human infections in a predictable annual cycle.
Starting every spring, regional and national “jackpot” shows, which attract serious swine competitors, bring together pigs from far-flung farms, causing new flu variants to spread across the country.
In the summer and fall, a much larger number of children bring their pigs to county or state fairs. At about 25 percent of fairs, at least one pig tests positive for the flu, which tends to spread widely, the researchers found. “By the end of the fair,” Dr. Bowman said, “you have 200 pigs shedding influenza virus.”
Fairs also put large crowds of people in close contact with pigs. “There’s children petting and touching the pigs and, at the same time, eating cotton candy and hot dogs and finger food,” Ms. Linder said.
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 had jumped from pigs to people during at least seven different Ohio fairs. “The idea that we’re seeing it right in front of us, multiple times — it was very surprising,” Dr. Bowman said.
Over the years that followed, the researchers worked to identify what made these shows risky. They found that although most fairs had hand sanitation stations, few had signs explaining how to use them — and almost no one did.
They also documented risks associated with the standard weigh-in procedure, in which the pigs were lined up, nose-to-tail, and guided onto a scale one by one. During that process, many pigs pressed their noses to vertical sorting panels used to keep the animals in place, and one infected pig could contaminate the common surface. “That results in accelerated transmission,” Dr. Bowman said. “It’s one pig to everybody in line behind them.”
The researchers, who have shared their findings with show organizers and health officials, say they have seen some changes, with many shows moving away from mandatory mass weigh-ins.
Some bigger shows and fairs, which traditionally last a week, have also begun sending most pigs home after 72 hours. That timeline means that pigs that are infected at a show will be gone before they start shedding the virus. “They’re not on public display, where they’re infecting other animals or people,” Dr. Bowman said.
Still, not all shows have been receptive to making these sorts of top-down changes. So, the Ohio State team is also working from the bottom up.
Healthy habits
When they were not competing, many of the children at the New Lexington show wandered into the vendor barn, where local artisans and organizations were hawking their wares. A booth near the entrance, where a cartoon pig in a lab coat invited children to enter the “Swientist Laboratory,” did a brisk business.
When a group of three preteens approached, Jacqueline Nolting, a researcher and educator on the Ohio State team, challenged them to test their hand-washing skills. She directed them to rub a clear gel into their hands and wash them thoroughly. Then, she pulled out a black light, announcing that any lingering traces of gel would glow. Six hands lit up.
“Oh, you’ve got lots of germs!” she exclaimed. “In the cracks of your knuckles — can you see how it got in the cracks of your knuckles?”
The activity is a mainstay of the Swientist program, which the team began developing in 2015 to teach young exhibitors how to keep their pigs, and themselves, healthy. At the New Lexington show, Dr. Nolting, who leads the program, also invited children to practice putting on and taking off personal protective equipment and gave away backpacks stuffed with activities, such as a biosecurity scavenger hunt. (Those who completed seven activities were entered into a drawing for an iPad.)
The researchers have become fixtures at swine shows across the country, which they attend with two objectives: to keep tabs on the virus by swabbing more pigs and to stop its spread by teaching children the basics of biosecurity.
Rob McCarley, of Circleville, Ohio, said that the first thing his 5-year-old twins want to do at a show is see what activities the Swientist team is offering. “They look forward to it,” he said. (And they seem to be paying attention; when one of the family’s pigs got sick this spring, one of the twins announced that they should isolate the animal.)
But success did not come overnight, and some families initially greeted the Ohio State researchers warily. “Like, ‘They’re targeting me, and they think my pigs are sick,’” said Kelly Morgan, who manages OH-PIGS, a circuit of Ohio swine shows. “The trust had to be built in the beginning.”
The scientists shared their data with exhibitors and reassured them that they were not “just here to poke and prod and take,” Dr. Bowman said. They pitched themselves as partners with shared goals.
“They gave us some great tips and some great ideas on how to keep our herd healthy,” said Lindsey Caldwell, of Leesburg, Ohio, whose two daughters show pigs. For instance, they advised that after returning from a show, the family should change or disinfect their shoes and quarantine the pigs that had attended, Ms. Caldwell said.
Her 16-year-old daughter, Maddie, has also passed some of these lessons onto peers in her agriculture classes. And despite her fear of needles, Maddie is among the children who have provided blood samples to the researchers, who are also collecting nasal swabs from young exhibitors in hopes of learning how often they are exposed to influenza and what their immune systems look like.
“I swab mainly to learn: Does the disease get to me?” said Ruth Ann Carity, 15, a swine exhibitor from Minster, Ohio. “I’m just curious to know.”
Still, some health recommendations, such as the advice to avoid eating or drinking around the animals, have been a tough sell. For many families, some of whom bring crockpots into the barn with them, sharing a meal at a show is a way of building community. And with shows that can last all day, it can also be a logistical necessity, Ms. Morgan said: “I mean, you have to feed kids or they get very hangry.”
Ultimately, the Ohio State team decided to ease off the recommendation, worried that it was so out of step with the culture that it would undermine their credibility. (It’s also not clear how much eating and drinking might increase the risk for people who are already spending hours sharing air with their pigs, Dr. Nolting acknowledged.)
It is hard to determine how effective the team’s efforts have been overall; the surveillance is still fairly new, and some flu seasons are naturally worse than others. “But I think we have moved the needle,” Dr. Bowman said. “There is change happening.”
Pigs are not the only farm animals that can carry dangerous pathogens, and the researchers recently began an educational program for people buying chicks at farm stores. They may create a cattle-focused program, too, Dr. Nolting said.
“We’ve talked about what our logo is going to look like, if it’s, ‘Swientist and Friends,’” Dr. Nolting said. “Maybe our pig in the lab coat has his buddies with him.”
Audio produced by Kate Winslett.