As the H5N1 bird flu virus sweeps through California’s dairy herds, the U.S. Department of Agriculture announced Friday that it is instituting a national milk testing program that should provide a much clearer picture of how widespread the virus is in the nation’s dairy industry.
Nearly nine months after the outbreak in dairy cows was first discovered, the USDA announced it will require farms to make milk available for testing if requested. Although the program is intended to be national, it will start with six states – California, Colorado, Michigan, Mississippi, Oregon and Pennsylvania – with additional states to be added later. Of the first group, California, Colorado, Michigan and Pennsylvania are already conducting bulk tank testing on dairy farms.
The statement announcing the new federal decision indicated that this measure will help inform the response to the outbreak and help farmers and farmworkers protect themselves from infections.
On Friday, the USDA had confirmed that 720 herds in 15 states had infected cows since the outbreak was first discovered in late March. The vast majority – 506 – were in California, which has been actively searching for infections, both among herds and people, since the first affected herds were discovered in late August. Many states, including some of the nation’s top dairy producers, have reported no infected herds — though it’s not clear whether that means a lack of infections or a lack of testing.
“Among many results, this will give farmers and farmworkers greater confidence in their animals’ safety and ability to protect themselves, and it will put us on a path to quickly control the spread of the virus across the country and stop,” said Secretary of Agriculture Tom Vilsack. in a press release.
Keith Poulsen, director of the Wisconsin Veterinary Diagnostic Laboratory, said he expects the testing program to identify states where farms are experiencing H5N1 outbreaks in herds that have gone undetected because farmers have refused to test for the virus.
A USDA spokesperson said that as infected herds are detected through the new program, they will be added a website The department claims that the affected states list the number of infected herds confirmed in each state. The website does not reveal the identity of the farms or even the provinces in which they are located.
The goal of the program, which has been in the planning stages for some time, is to eliminate the virus among the country’s dairy cows, said Poulsen, who is part of a shareholder group that has consulted with the USDA on the effort. .
Getting it off the ground has been a challenge, he admitted, because dairy farmers are reluctant to agree to anything that could lead to the identification of affected farms. “That’s the big piece and why it took so long,” Poulsen said.
Flu virologist Richard Webby said it makes sense to try to get a better handle on where the virus is spreading. But it won’t by itself solve the problem, he said, noting that California has been aggressively searching for affected herds using bulk tank testing.
“That really hasn’t helped control the spread with current actions,” said Webby, director of the World Health Organization’s Collaborating Center for Studies on the Ecology of Influenza in Animals, based at St. Jude Children’s Research Hospital in Memphis. , Tenn. “At least in my opinion, there is no direct correlation between testing this milk and actually doing anything other than what is happening now.”
The U.S. response to the outbreak in cows has been widely criticized by influenza experts at home and abroad, who view the continued spread of the virus in mammals — mammals that humans come into regular contact with — as playing with fire. H5N1 is a virus capable of infecting wild birds; Although sporadic human infections have occurred, the virus currently does not have the ability to spread easily to and among humans. If it were to acquire the mutations that make this possible, it is believed the virus would cause a pandemic.
A study published Thursday in the journal Science suggested that this version of the virus may mutate more easily to allow human-to-human transmission than earlier versions of H5N1. Scientists at Scripps Research in La Jolla, California, reported that a single change at a key position on the hemagglutinin, the main protein on the virus’s surface, allows it to easily attach to cells in the human upper respiratory tract.
In the nearly thirty years since H5N1 was first detected in China, approximately 1,000 human infections have been identified. Of these, just under 50% were fatal.
Before this year, the United States had recorded just one human case, in April 2022, in a person involved in a poultry cull on a Colorado farm battling an H5N1 outbreak. But this year alone, the country has done just that recorded 58 casesmost among dairy farm workers or poultry clearers. However, two of the cases involved people for whom no source of infection could be identified.
(Two more infected poultry culls who tested positive were announced by Arizona late Friday. They have yet to be confirmed by the Centers for Disease Control and Prevention.)
Critics wonder why the USDA hasn’t tried more aggressively to detect where the virus is spreading in cows. The goal, they emphasize, should be to get the virus out of the cow population. But the fact that the virus rarely kills cows has set back this effort. Many farmers believe it is not that bad and have resisted efforts to locate infected herds. The USDA’s efforts so far have not been as proactive as experts think would be necessary to stop the spread among cows.
Tests have shown that raw milk from cows infected with H5N1 contains extremely high levels of the virus. It is not known whether humans can become infected by drinking virus-contaminated milk, but studies have shown that mice fed raw milk became so ill that they had to be euthanized. And there have been several reports of dead cats on affected farms.
But studies conducted by the Food and Drug Administration and others have shown that pasteurization kills the virus.
The new federal order allows USDA to obtain raw milk samples from any player in the production and distribution network. It also requires ranchers identified as having positive cattle to provide information that will allow the agency to trace the source of the virus and track the movement of cows. And it reiterates a requirement from an earlier order that private labs and state veterinarians that detect positive cows must report them to the USDA.