Gov. Gavin Newsom declared a state of emergency for California Dec. 18 due to highly pathogenic avian influenza, which continues to spread through poultry and dairy farms.

The move came the same day as the U.S. Centers for Disease Control and Prevention announced the nation’s first serious human illness due to bird flu, in Louisiana. That case was confirmed Dec. 13.

Bird flu also has spread from the Central Valley to dairy farms in Southern California.

The declaration enhances the state’s preparedness and accelerates ongoing cross-agency response efforts to the disease, which has been spread by migrating wild birds.

“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,” he said.

Human cases

Newsom and the CDC said the risk to the public remains low and no person-to-person spread of avian influenza has been detected to date.

Overall, there have been 61 human cases in the U.S., and California has had 34. All but one of the individuals were exposed to infected cattle, and it isn’t clear how the other individual contracted the disease.

Washington has 11 cases and Oregon one.

The person who is severely ill in Louisiana had exposure to sick and dead birds from backyard flocks. This is the first human case of bird flu in the U.S. that has been linked to backyard flocks, according to the CDC.

The H5N1 avian influenza virus infection has previously been associated with severe human illnesses in 2024 and prior years, including illnesses resulting in death.

“This case underscores that, in addition to affected commercial poultry and dairy operations, wild birds and backyard flocks also can be a source of exposure,” stated the CDC, in a news release.

The agency encouraged hunters and other bird enthusiasts to take precautions as people with recreational exposures to infected animals also are at higher risk of infection.

Birds and cattle

California has had 19.3 million birds affected by the outbreak in backyard and commercial flocks as of Dec. 18. That’s second in the nation to Iowa’s 29.2 million birds.

Farmers in the state euthanized 3 million birds impacted by highly pathogenic avian influenza during the first week of December alone.

Washington has had 1.86 million birds affected during the course of the outbreak, Oregon has had 907,000 and Idaho has had 13,500.

California also has had bird flu detected in 649 dairy herds and nearly half of that number came in the past 30 days.

The U.S. has had 865 such instances in cattle in 16 states. Idaho has had 35 herds with avian influenza during the course of the outbreak.

Protecting the public

California has taken numerous steps to minimize farm worker exposures, reduce raw dairy product contamination and mitigate the spread of the virus, including distributing millions of pieces of personal protective equipment to high-risk employees at dairies.

The state also has been working with local health and ag officials, as well as the CDC, the U.S. Food and Drug Administration and the U.S. Department of Agriculture.

Bird flu was first detected in the U.S. in the wild bird population in South Carolina in January 2022.

In March 2024, an outbreak of avian influenza in dairy cows was first reported in Texas and Kansas. California immediately began testing for the disease and its first confirmation occurred in late August.

More bird flu coverage

California loses 8.4 million birds in past month to bird flu

USDA orders milk sampling in bird flu surveillance

Commentary: Oregon lawmakers have opportunity to get ahead of potential bird flu crisis

Oregon confirms its first human case of highly pathogenic bird flu

California shell egg prices surge as bird flu spreads

Bird flu confirmed in pig at small Oregon farm