Three of America’s top milk-producing states aren’t a part of federal surveillance testing for bird flu even as a new variant is turning up in dairy cattle, in what some public health experts say is a troubling gap in the national effort to identify and detect the spread of the virus.
The U.S. Department of Agriculture started a voluntary milk-testing program in December, after the virus was found to have jumped to cattle in March 2024. The recent outbreak of avian influenza in the U.S. was first detected in 2022, but has picked up steam over the last year, decimating poultry farms nationwide, killing tens of millions of birds and driving up the price of eggs.
While the risk to humans remains low, many public and animal health experts argue that broad, nationwide testing of milk is critical to containing virus cases that might otherwise go undetected, giving the variants more opportunities to spread to animals — and to humans.
“It is incredibly difficult to control a disease of national importance unless we have a robust surveillance system in place,” said Dr. K. Fred Gingrich II, executive director of the American Association of Bovine Practitioners, which represents cow veterinarians.
“If we were testing every dairy, I don’t think you’d have any cases slipping through the cracks.”
Yet Texas, Wisconsin and Idaho, three of the country’s top five milk-producing states, aren’t participating in the voluntary federal testing program. And though there are efforts underway to get them on board, it’s not clear when they will join, or how long it will take.
Texas had the first known case of bird flu in cattle, the first person believed to be infected by a mammal, and a case in dairy cattle as recently as December. But the state’s agriculture commissioner, Sid Miller, said surveillance milk testing was unnecessary, since there are currently no active cases of bird flu in the state’s commercial cattle or poultry.
“It’s not a big deal, if you measure by how many herds are affected,” Miller said in an interview.
Requiring milk testing for bird flu would be “just more regulation, more cost, more oversight. It’s not necessary,” he said, adding that the state still considered bird flu to be a significant threat but that bovine vaccine development should be a major focus.
A separate agency, the state’s Animal Health Commission, is working with federal officials to develop a surveillance testing program for bird flu, according to the USDA.
Just last week, the USDA announced it had discovered a new strain in cattle, caught in Nevada through the federal milk-testing program.
The detection “is a testament to the strength of our National Milk Testing Strategy,” the USDA said in a statement to NBC News. The agency said last month that testing samples are being taken from nearly three-quarters of the country’s milk production. More states have come on board since then, with nearly 40 now participating. The USDA is aiming to enroll all 48 continental states.
One person has died and at least 68 people have been infected in the U.S. since the beginning of 2024, most often after close or prolonged contact with infected animals, according to the U.S. Centers for Disease Control and Prevention.
Richard Webby, an animal influenza expert at St. Jude Children’s Research Hospital, said the milk testing is a critical tool for helping disease specialists monitor how the virus is evolving, especially in ways that could make it easier to transmit from person to person.
“We can figure out if there are changes that are occurring in the virus that increase human risk,” he said.
Pasteurization effectively kills bird flu that is found in milk, rendering it safe to drink, though farmworkers are still coming into contact with raw milk and cattle that could be infected. More than 960 dairy herds nationwide have been affected so far, and the federal government requires all lactating dairy cattle to be tested for bird flu before being moved across state lines.
The testing is carried out by state and USDA officials, using raw milk samples from bulk silos, where milk from farms is collected before it’s sent to processors that pasteurize, homogenize and package it. The USDA has a national network of labs for bird flu testing, and the federal program requires a minimum of four testing rounds over six months, with follow-up testing that aims to trace any positive results back to individual farms. The agency also provides free testing to individual farmers.
Wisconsin said it “continues to work toward” enrolling in the USDA’s testing program and is working closely with state and federal partners to monitor bird flu developments, according to a spokesperson for the state agriculture department.
Idaho did not respond to requests for comment but is not currently participating in the program, according to the USDA.
Bird flu, like many viruses, can be often detected through testing days before dairy cows exhibit any symptoms, health experts said, which can help farmers quickly take steps to contain the virus, quarantine affected animals and test humans who were potentially exposed.
“The more lead time we have in identifying where the virus is — that allows us to bolster the protection for the workers as well,” said Dr. Kay Russo, a Colorado veterinarian who helped identify the first confirmed case of bird flu in cattle last year.
“If we’re flying blind in a particular state, where we don’t know what the status is, we really can’t say for certain what the risk is,” Russo added.
The frequency of milk testing varies widely across the U.S., even within the states enrolled in the USDA program.
While testing occurs monthly in some states, after outbreaks in dairy cattle last year, Colorado required all farms to conduct weekly milk testing to help contain the disease, which has continued.
“It helps our poultry and dairy industries sleep at night,” said Dr. Maggie Baldwin, Colorado’s state veterinarian, who said that the state’s testing regime helped detect cases before animals displayed symptoms. “We know where it is and where it isn’t.”
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