Bird flu's rapid spread prompts California to declare a state of emergency
California Gov. Gavin Newsom declared a state of emergency Wednesday to combat bird flu, which has spread to more than a quarter of all the state's dairies in the last month and infected 34 state residents.
The emergency declaration expands the amount of money Newsom can spend fighting the H5N1 virus, which was first detected in California cows in August, and has swept across the nation’s largest dairy-producing state. As of Monday, 649 dairies have had infections, including 313 in the last 30 days and about 120 just in a week, U.S. Department of Agriculture data shows.
All human infections reported so far had been mild until Wednesday when federal officials said a Louisiana resident hospitalized with a presumptive bird flu infection has the first U.S. case classified as "severe."
The person had been exposed to sick and dead birds suspected of being infected with H5N1, the Louisiana health department said last week. It is the same flu strain that sickened a teen in Canada, but not the one that has infected cattle, according to the Centers for Disease Control and Prevention.
The exact cause of the spread among California cattle isn't clear, said Anja Raudabaugh, CEO of Western United Dairies, which represents most California dairy farmers. Movement of cattle is thought to have first led to the spread, though later, shared milking equipment and personnel likely drove the infections. Testing has dramatically increased to detect outbreaks earlier, too.
What's known is the virus has substantial effects on the cows that produce tens of thousands of gallons of milk each year, the farmworkers who care for the livestock, and farmers trying to keep businesses afloat.
“You do not want this on your herd,” Raudabaugh said. “It’s that bad.”
Consumers shouldn’t see impacts to pasteurized milk, cheese, or yogurt at their grocery stores, said Raudabaugh. The pasteurization process destroys the virus’s ability to live or replicate, making pasteurized milk safe.
However, raw milk has been shown to contain the virus. Two raw milk producers in California have had to recall products due to virus present in unpasteurized milk, including one product announced Saturday.
There have now been 61 confirmed human cases of bird flu in the U.S. during 2024, according to the CDC.
What happens to dairies affected by bird flu
Over the long term, Raudabaugh worries about farms' ability to recoup losses in milk production when cows recover.
California has approximately 1,100 dairies, mostly concentrated in the state's fertile Central Valley, that produce approximately 41 billion gallons of milk annually for an economic value of nearly $20 billion as of 2018, according to a 2019 University of California, Davis, analysis for the California Milk Advisory Board.
Bird flu was first detected in Texas dairies in the spring after officials believe one herd was infected by wild birds. So far, 16 states have had outbreaks in cows, with 865 herds affected. Three-quarters of infected herds come from California.
In California, outbreaks in dairies started in and around Tulare County, before moving up and down the Central Valley and now trekking northward, Raudabaugh said.
What does a state of emergency do?
California’s declaration opens up more funding to respond to the crisis, similar to a natural disaster like a forest fire.
The proclamation by Newsom, a Democrat, allows the state to streamline and expedite resources to address the rapid spread of bird flu across the state, his office said in a news release.
“This proclamation is a targeted action to ensure government agencies have the resources and flexibility they need to respond quickly to this outbreak,” Newsom said in a statement. “Building on California's testing and monitoring system ‒ the largest in the nation ‒ we are committed to further protecting public health, supporting our agriculture industry, and ensuring that Californians have access to accurate, up-to-date information.”
Over the summer, Colorado experienced large bird flu outbreaks among poultry and cattle that led to several outbreaks among livestock workers. Gov. Jared Polis, a Democrat, issued a disaster declaration then to help poultry farms.
What happens to cows and other animals when they catch bird flu
The H5N1 virus typically doesn't kill cows the way it does birds and chickens. Estimates have placed mortality rates in cows at no more than 2%.
Once cows are sick, their digestion process of ruminating stops, they stop drinking water, and they develop a fever, Raudabaugh said. In triple-digit Central Valley temperatures, this may have resulted in some cows dying from heat stress in a hot October. The cool fall and winter months in California have meant fewer cows are getting severely ill and dying, she said.
Before cows develop these symptoms, their milk shows signs of the virus, Dr. K. Fred Gingrich II, executive director of the American Association of Bovine Practitioners, an organization representing veterinarians who treat cows, previously told Paste BN. Bulk milk testing can help detect bird flu circulating in herds before large outbreaks occur.
After a fever breaks, cows resume eating, drinking and ruminating. The milk production then returns over several weeks, but it still levels out about 20% to 30% less than before a bird flu infection, said Dr. Michael Payne, a researcher and outreach coordinator at the Western Institute of Food Safety and Security, a center within the University of California, Davis, School of Veterinary Medicine.
Cats have also gotten sick with bird flu circulating in cows. When officials first identified bird flu in Texas cows, they did so, in part, from dead cats that likely drank raw milk in barns. Last week, Los Angeles County health officials identified two indoor cats that died from suspected bird flu infections after they drank recalled raw milk.
What happens to people with bird flu
So far, most people infected with bird flu in the U.S. have had mild infections. The risk to the general public remains low, though livestock workers are at heightened risk, officials have said.
Of the 61 identified people infected with bird flu across the U.S., more than half have been in California, CDC data shows.
Only one of the U.S. cases, a child in the San Francisco Bay Area, has had no connection to a dairy or poultry farm. State officials said the child had only mild symptoms of cold and flu.
The state’s 33 remaining cases have been in dairy workers. Their symptoms have typically been limited to eye redness and mild respiratory symptoms, and they soon recovered.
Officials and experts worry about the potential for the virus to mix with the seasonal flu, which could lead it to become more transmissible or severe. The CDC has sought to vaccinate livestock workers against seasonal flu to prevent this.
Why isn't more being done to contain bird flu?
Despite quarantines of farms, outbreaks continue to occur, which suggests other routes of transmission, Payne, of UC Davis, said in an email.
These may include potential spread from wildlife such as rodents or birds living on or near farms. Additionally, flying insects and even dust plumes in the wind may are being studied, Payne said. "As a whole, we still have a lot more to learn about the multiple ways the (bird flu) virus is being spread through our domestic species," he said.
In December, the USDA announced it would begin bulk testing of milk supplies to track the virus.
Given the rapid spread in California dairies, Raudabaugh said the U.S. needs to pursue a vaccine development “Operation Warp Speed” for cows, on par with the one during the Trump administration that rapidly developed COVID-19 vaccines for people.
Bird flu “has been so catastrophic for our herds,” Raudabaugh said. “We have to do something really drastic in order to prevent this. Relying on herd immunity is not a good strategy.”
On Oct. 24, the Department of Health and Human Services announced USDA had started safety trials for vaccines in cows. While research into the vaccines is promising, it's still early, USDA told Paste BN over email.
For people, the federal government has stockpiled 10 million doses of vaccine that it believes will be effective against the current strain of bird flu, though because of the mildness of illnesses so far and lack of human-to-human spread, it has not yet made the shots available to farmworkers or the general public.
"We can’t get either cattle or human vaccines on the market fast enough," Payne said.
(This story was updated to add new information.)