It’s been a quiet summer for the bird flu outbreak. Egg prices fell slightly, fewer flocks of sick poultry were slaughtered on farms, and officials sighed.
“It was great,” said Shauna Voss, deputy director of the Minnesota Animal Health Commission.
But it didn’t last.
Avian flu is spreading again as wild waterfowl, including geese, ducks and cranes, begin their seasonal migrations. As birds travel, they hang out in lakes and ponds and share viruses.
In poultry, bird flu cases are rising faster than expected. Last month, more than 4 million poultry in states including Minnesota and Iowa were culled after testing positive for the virus, called H5N1. This trend is consistent with a surge in infections found in wild birds in northern regions.
Some state officials are bracing for a difficult fall, with cases typically surging over the past few years.
“We saw our first positive test last week,” Iowa Agriculture Secretary Mike Naig said. The incident occurred at a turkey farm in Calhoun County. “So the question that remains for us is how widespread it will be and what kind of downfall it will have.”
He added that it was too early to tell what impact the outbreak would have on egg prices.
“The only honest answer to that is we’ll have to wait and see. I wish I could give you more than that,” Naig said.
This is the fourth fall to see a rise in avian flu infections, a sign that the virus is becoming endemic in wild birds and could pose a continuing threat to poultry.
“It’s not going away. It seems to be pretty built-in,” Voss said.
The more the virus circulates, the more it risks opening up an easy way to infect humans. If this becomes a problem, some experts worry that the Trump administration’s cuts to mRNA research could hamper scientists’ ability to quickly develop new vaccines. But for now, the health risk to people is still low.
As fall progresses, officials, wildlife experts and virologists are in watch and wait mode.
“It’s an exciting time,” said Declan Schroeder, associate professor of virology at the University of Minnesota College of Veterinary Medicine. “Everyone is holding their breath and waiting to see what will happen.”
Avian influenza was first detected in U.S. commercial flocks in February 2022, after previous transmission to wild birds. The virus is almost always fatal to poultry, with more than 175 million birds culled or killed as of this summer. Two years ago, researchers were surprised to learn that avian flu had spread to dairy cows and was found in raw, unpasteurized milk, leading to significant changes in farm practices and milk testing.
At least 70 people —mostly farm workers in close contact with birds or cattle—were infected. One person died.
Scientists believe wild birds tend to spread the disease on poultry farms in several ways, including direct contact, contamination of feed, and workers bringing contaminated material into their housing. That’s why migration season can be a catalyst.
“If one sick bird moving through an area infects other birds, the math suggests that it will spread really quickly,” said Michael Ward, a professor of natural resources and environmental sciences who studies migration at the University of Illinois.
Ward added that habitat restrictions force birds to congregate and share space, making the spread of the virus more likely. In Illinois, wetland habitat has declined as the state deals with drought.
“It’s the perfect combination for disease to emerge,” Ward said.
In response to questions about the increased detection of avian flu and the federal government’s response plan, the U.S. Department of Agriculture noted: Five strategies announced in FebruaryThis included $100 million to research new biosecurity measures and develop poultry vaccines.
Countries like France are already vaccinating poultry, but the USDA said it is continuing to evaluate whether the United States should do so. The FDA has not approved such a vaccine, and its rollout would impact U.S. exports.
“We really believe that an effective vaccine strategy would be very beneficial to egg and turkey producers, but we understand that it has to be done carefully to avoid impacting other markets,” Iowa’s Naig said. “USDA has put some focus on this, and now we’re waiting to see what the vaccine strategy looks like.”
Scientists have long been concerned that bird flu viruses may eventually gain the ability to spread effectively between people. Even considering that the current risk to humans is low, Dr. Peter Chin-Hong of the University of California, San Francisco, School of Medicine, who studies infectious diseases, advises taking basic steps to prevent H5N1 infection as well as seasonal flu.
“Get your flu shot. Don’t drink raw milk and don’t eat unpasteurized cheese, especially when cases are going around. Don’t let your cat be fed outside during migratory season,” Chin-Hong said.
A scenario where a person is simultaneously infected with H5N1 and seasonal flu could be problematic. That’s because avian flu viruses can more easily rearrange their genetic code to suit humans.
The Centers for Disease Control and Prevention stopped requesting coordination with health care providers for H5N1 this spring. Chin-Hong laments these changes. He hopes the agency will resume the call and disagrees with the Trump administration’s end of funding for mRNA vaccine research. Biotechnology company Moderna was developing an avian flu vaccine using an mRNA platform, but the Department of Health and Human Services revoked its approval.
The CDC did not respond to a request for comment.
