It was a quiet summer for bird flu: egg prices fell slightly, fewer sick birds were slaughtered on farms, and officials sighed.
“It was wonderful,” said Shauna Voss, deputy director of the Minnesota Animal Health Board.
But it didn't last long.
Bird flu is spreading again as wild waterfowl – geese, ducks and cranes – begin their seasonal migrations. As they travel, the birds mingle in lakes and ponds and share viruses.
Among poultry, cases of avian influenza are rising earlier than expected. Over the past month, more than 4 million poultry have been killed in states including Minnesota and Iowa after members of their flocks tested positive for a virus called H5N1. This trend is consistent with a surge in infections found among wild birds in northern states.
Some state officials are bracing for a challenging fall, with cases typically rising sharply in recent years.
“Last week we had our first confirmed positive,” Iowa Secretary of Agriculture Mike Naig said. The incident occurred on a turkey farm in Calhoun County. “Then the question for us is how big it will be and what kind of decline awaits us.”
He added that it was too early to tell what impact the outbreaks would have on egg prices.
“The only honest answer to that question is we'll have to see. I wish I could give you more,” Naig said.
This is the fourth fall in which avian influenza cases have risen, a sign that the virus is becoming endemic in wild birds and could pose an ongoing threat to poultry.
“It's not going away. It seems to be ingrained,” Voss said.
The more the virus circulates, the higher the risk that it will open the door to easily infecting people. If that becomes a problem, some experts worry the Trump administration's cuts to mRNA research could prevent scientists from quickly developing a new vaccine. However, at this time the risk to public health remains low.
As fall progresses, officials, wildlife experts and virologists are in watch-and-wait mode.
“It's an exciting time,” said Declan Schroeder, assistant professor of virology at the University of Minnesota College of Veterinary Medicine. “Everyone is waiting with bated breath to see what happens.”
Avian influenza was first detected in a commercial flock in the United States in February 2022, after previously circulating among 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 Surprised to discover that bird flu has spread to dairy cows and was discovered in raw, unpasteurized milk, leading to many changes in agricultural practices and milk testing.
at least 70 people — mainly agricultural workers who had close contact with birds or cows were infected. One person died.
Scientists say wild birds typically transmit disease to poultry farms in several ways: through direct contact, through contamination of feed or when workers bring contaminated materials into barns. This is why migration season can be such a catalyst.
“If you have one sick bird that moves through an area and infects others, the math suggests it will spread very quickly,” said Michael Ward, a professor of natural resources and environmental sciences at the University of Illinois who studies migration.
Ward added that habitat restrictions force birds to congregate and share space, increasing the likelihood of the virus spreading. In Illinois, wetland habitat has declined as the state battles drought.
“It’s the perfect combination for disease to occur,” Ward said.
In response to a query about the rise in avian influenza cases and how the federal government plans to combat it, the USDA pointed to five-prong strategy released in Februarywhich included $100 million for research into new biosecurity measures and the development of poultry vaccines.
Countries like France is already vaccinating poultrybut the USDA said it continues to evaluate whether the U.S. should do so. The agency has not approved such a vaccine, and its rollout would impact U.S. exports.
“We do believe that an effective vaccination strategy will be very beneficial for egg and turkey producers, but we recognize that it needs to be done carefully so as not to impact other markets,” said Iowa's Naig. “The USDA has given this issue some attention, and now we're waiting to see what that vaccination strategy might look like.”
Scientists have long been concerned that the bird flu virus could eventually develop the ability to spread effectively between people. Even with the low risk to people at this time, Dr. Peter Chin-Hong, a professor of medicine at the University of California, San Francisco, who studies infectious diseases, advised people to take basic steps to prevent infection with H5N1 as well as seasonal flu.
“Get a flu shot. Don't drink raw milk, don't eat unpasteurized cheese, especially when cases are spreading. Don't let cats feed outside during migratory bird season,” Chin-Hong said.
A scenario in which a person becomes infected with both H5N1 and seasonal influenza at the same time could be problematic because it would allow the avian influenza virus to more easily rearrange its genetic code to suit the individual's needs.
This spring, the Centers for Disease Control and Prevention stopped holding H5N1 coordination meetings with health care providers, a change Chin-Hong laments. He hopes the agency will resume calls and disagrees with the Trump administration cutting off funding for mRNA vaccine research. The biotech company Moderna was development of an avian influenza vaccine using an mRNA platformbut the Department of Health and Human Services canceled its grant.
The CDC did not respond to a request for comment.
