The California Department of Public Health, in coordination with local health partners and the Centers for Disease Control and Prevention, is investigating a possible human case of H5N1 bird flu in an individual who had contact with infected dairy cattle in the Central Valley.

“Ongoing health checks of individuals who interact with potentially infected animals helped us quickly detect and respond to this possible human case. Fortunately, as we’ve seen in other states with human infections, the individual has experienced mild symptoms,” said Dr. Tomás J. Aragón, CDPH Director and State Public Health Officer. “We want to emphasize that the risk to the general public is low, and people who interact with potentially infected animals should take prevention measures. CDPH continues to support local health departments and farms with prevention recommendations, health checks and guidance on proper notification, testing and treatment.”

The risk to the general public remains low, but people who interact with infected animals, like dairy or poultry farm workers, are at higher risk of getting bird flu.

CDPH recommends that personal protective equipment, or PPE, such as respirators (N95 masks), eye protection (face shields or safety goggles) and gloves be worn by anyone working with animals or materials that are infected or potentially infected with the bird flu virus. Wearing PPE helps prevent infection. Please see CDPH’s Worker Protection from Bird Flu for full PPE guidance.

Pasteurized milk and dairy products continue to be safe to consume, as pasteurization is fully effective at inactivating the bird flu virus. As an added precaution, and according to longstanding state and federal requirements, milk from sick cows is not permitted in the public milk supply.

The infected individual is a worker at a Central Valley dairy facility experiencing an outbreak of bird flu among dairy cattle. The individual experienced mild symptoms, reporting only conjunctivitis (eye redness).

Once the local health department was notified, their public health laboratory tested the individual for H5N1 and CDPH was notified of a “presumptive positive” result. Specimens have been forwarded to the CDC for confirmatory testing. In accordance with CDC guidance, the individual is being treated with antiviral medication and is staying home. To protect patient privacy, additional details will not be provided.

CDPH has helped coordinate and support outreach to dairy producers and farm workers on preventive measures that have helped keep human cases low in other states with bird flu outbreaks.

CDPH continues to support local health departments in distributing PPE from state and federal stockpiles directly to affected dairy farms, farmworker organizations, poultry farm workers, those who handle raw dairy products, and slaughterhouse workers.

To protect California farm workers from bird flu, during the last four months CDPH has distributed more than 340,000 respirators, 1.3 million gloves, 160,000 goggles and face shields, and 168,000 bouffant caps.

In addition, CDPH is working closely with local public health laboratories and local health departments to provide health checks for exposed individuals and ensure testing and treatment are available when needed.

As one of the 14 states with infected dairy herds, California also received 5,000 additional doses of seasonal flu vaccine for farm workers from the CDC. CDPH is working to distribute the doses to local health departments with the highest number of dairy farms.

CDPH has been tracking bird flu and making preparations for a possible human infection since the state’s first detection in poultry in 2022. CDPH partners closely with the California Department of Food & Agriculture (CDFA) on a broad approach to protect human and animal health. CDPH and the CDC use both human and wastewater surveillance tools to detect and monitor for bird flu, and work closely with local health departments to prepare, prevent, and lessen its impact on human health.

People exposed to infected animals should monitor for the following symptoms for 10 days after their last exposure: eye redness (conjunctivitis), cough, sore throat, runny or stuffy nose, diarrhea, vomiting, muscle or body aches, headaches, fatigue, trouble breathing, and fever. If they start to feel sick, they should immediately isolate, notify their local public health department, and work with public health and health care providers to get timely testing and treatment.

CDPH recommends that all Californians, especially workers at risk for exposure to bird flu — receive a seasonal flu vaccine. Although the seasonal flu vaccine will not protect against bird flu, it can decrease the risk of being infected with both viruses at the same time and reduce the chance of severe illness from seasonal flu.

For the latest information on the national bird flu response, see the CDC’s Bird Flu Response Update.