Nearly 20 million chickens, ducks and turkeys on farms in the San Joaquin Valley have been “depopulated” – a polite term for killed – as bird flu, or avian influenza, continues to infect poultry flocks across California and the U.S.

That’s almost 85% of all avian flu cases among both commercial and backyard flocks statewide since the current national outbreak of the virus began in February 2022.

But there are some signs that the virus may be slowing down.

“Outbreaks of highly pathogenic avian influenza (HPAI) in commercial table egg layer flocks in the first two months of 2025 have resulted in the depopulation of 30.1 million birds” nationwide, the U.S. Department of Agriculture’s Livestock and Poultry Program reported on Feb. 28.

Within the Valley, from San Joaquin County in the north to Kern County in the south, more than 750,000 birds from infected flocks have been culled just in the first two months of 2025 to prevent the continuing spread of the bird flu virus.

But the virus is not confined only to poultry or other birds. Statewide, California health officials report there have been 38 confirmed cases among humans, with most of those occurring within the San Joaquin Valley. Nationwide, the U.S. Centers for Disease Control and Prevention reported there have been 70 bird flu cases in people in 12 states, including one death.

Dairies across the state are also being affected. A total of 749 confirmed cases of bird flu among dairy cattle have been reported in California through the entirety of the outbreak, according to the U.S. Department of Agriculture, amounting to more than three-quarters of all confirmed livestock cases reported in 18 states nationwide.

Dr. Annette Jones, California’s state veterinarian and director of Animal Health and Food Safety Services, told a joint session of the state Senate agriculture and health committees on Wednesday (March 5) that the winter wave – “the worst outbreak this country has ever seen” – may be relenting.

Among dairies, “the good news is that we are lifting quarantines now faster than we are placing them,” Jones said. “Now we are getting ahead of the virus. … In the Central Valley we are going in a very positive direction.”

A growing number of poultry farms that underwent “rapid euthanasia of those flocks” are starting to get a green light to repopulate their facilities after disinfecting and testing negative for the virus.

Egg Prices Feeling the Effects

The ongoing deadly outbreak among California’s commercial poultry flocks comes at a point when people are clamoring about high food prices, including eggs. More than 11 million of the fowl culled in the Valley region are commercial laying hens, putting a huge dent in the egg supply, consequently contributing to egg prices that have climbed by more than $1 per dozen in California since the start of the year.

The USDA reports that “California compliant” eggs (eggs that have been subjected to measures to reduce the risk of salmonella contamination) were selling at $8.97 per dozen on Jan. 2, but as of Feb. 28 were up to $10.07 per dozen.

That creates additional challenges in a region in which more than one out of every five households – almost 280,000 families – rely on SNAP (Supplemental Nutrition Assistance Program) benefits, formerly known as food stamps, to help them put food on the table.

The winter wave of the virus among poultry flocks from October through February far outpaced the previous winter, with losses among egg-laying flocks amounting to as many as four million dozen eggs each week, Jones said.

The USDA announced in late February that it would undertake a $1 billion effort to battle the outbreak and lower egg prices. Agriculture Secretary Brooke Rollins laid out a plan by the Trump administration to spend $500 million on biosecurity measures and $400 million for financial relief to affected farmers.

The USDA plan also includes $100 million for vaccine development and exploring ways to minimize depopulation of infected flocks.

Beyond egg-laying hens, more than 6 million broiler chickens and breeders have been culled in the Valley, along with about 720,000 turkeys, and more than 600,000 meat and breeder ducks.

Most of California’s Human Cases in the Valley

More than half of the 70 confirmed human cases of avian flu in the U.S. have occurred in California. So far, all but two of California’s 38 cases have contracted the virus through exposure to dairy herds.

In the Valley, at least 31 cases of bird flu among humans have been reported since October:

• 18 in Tulare County
• 4 in Kern County
• 3 in San Joaquin County
• 2 in Kings County
• 2 in Madera County
• 1 in Stanislaus County
• 1 in Fresno County

Nearly all of the Valley cases have been the result of contact with infected dairy cattle or other livestock, according to health officials.

The Fresno County Department of Public Health and the CDC report that the virus can spread through droplets or particles from the feces, raw milk or saliva of an infected animal. The virus can enter through a person’s eyes, nose or mouth, including through breathing. The most at-risk people are those who handle raw milk from infected cows, those who care for sick animals or who clean livestock pens or barns.

Human symptoms include tears, pink eye or eye redness or irrigation; fever of 100 degrees or higher; cough; sore throat; breathing difficulty or shortness of breath; headaches; runny or stuffy nose; muscle or body aches; or diarrhea.

About the Author

Tim Sheehan is the Health Care Reporting Fellow at the nonprofit Central Valley Journalism Collaborative. The fellowship is supported by a grant from the Fresno State Institute for Media and Public Trust. Contact Sheehan at tim@cvlocaljournalism.org.