H5N1 bird flu

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Last content update: 12/6/24    

What is H5N1 bird flu?

H5N1 bird flu is a specific subtype of influenza virus that is widespread in wild birds. H5N1 bird flu is also called highly pathogenic avian influenza (HPAI). H5N1 bird flu can infect wild birds, poultry, and some mammals such as cows, cats, and humans. To date, there has been no confirmed human-to-human spread of H5N1 bird flu viruses in the United States. However, there have been cases in the United States under investigation that have not been tied to direct animal contact. Human cases caused by contact with infected animals are increasing, and spread of the virus may lead to changes that make it more likely to infect humans or enable it to spread from human to human.

What is the Public Health Department doing?

Sharing information

The County of Santa Clara Public Health Department is working with health and agriculture partners at the local and state level to ensure stakeholders get accurate information to best protect the health of the community. The Public Health Department shares information with agricultural workers on how to identify sick animals and protect themselves from infection. This is part of the Department’s ongoing work to ensure community safety by preparing in advance for various diseases, even before there are cases here.

Testing and monitoring for presence of H5 influenza

The Public Health Department is collecting human influenza samples from healthcare facilities for further testing. This testing can identify if samples contain H5 influenza or a common human influenza strain. As of the latest update, there have been no H5 influenza detections in these human samples from Santa Clara County residents.

The Department is monitoring wastewater testing results from the national WastewaterSCAN program.

To view data on wastewater testing for the H5 influenza subtype in the four Santa Clara County sewersheds, refer to the WastewaterSCAN Dashboard. For data on the level of all influenza virus detected in wastewater in Santa Clara County, refer to the Respiratory virus data dashboard. These dashboards indicate the level of influenza virus particles present in wastewater, but do not indicate how the virus was introduced into the wastewater.

The Department is also performing testing for H5 in samples of raw milk for sale in Santa Clara County and reporting all positive or indeterminate findings to state authorities.

What can you do?

The current risk to the general public from H5N1 bird flu is unknown. Risk for dairy workers is likely increasing throughout California, as an increasing number of infected dairy herds are reported in California counties outside of Santa Clara County. The winter flu season may contribute to changes in the virus that allow it to develop the ability to spread between humans, because it is possible people will be infected with both H5N1 bird flu and the circulating seasonal flu.

While the overall risk remains unknown, people should follow these recommendations:

Get your seasonal flu shot

The seasonal flu shot protects against the other strains of influenza currently circulating in the community. Getting your seasonal flu shot decreases the likelihood you'll get sick this winter and decreases the likelihood you could have both H5N1 bird flu and seasonal flu at the same time.

Food safety

• Public Health recently detected H5 in retail samples of raw milk available for purchase in Santa Clara County. These detections increase the concerns around eating and drinking raw milk and raw milk products. We do not know the risks to humans of getting ill with H5N1 bird flu from consuming raw milk products that are contaminated with H5N1 bird flu. Animal studies indicate infection is possible if contaminated products are consumed, as well as through accidental inhalation or splashes to eyes or nose. 
• Health authorities advise you not to prepare or eat unpasteurized (raw) milk or raw cheese. Raw milk and cheese have not gone through a process called pasteurization that kills disease-causing germs. For more information about how raw milk can make you sick, visit the CDC’s Raw Milk webpage.
• Cook beef and poultry products, including eggs, to the right temperature. For more information on minimal internal temperatures, refer to the CDC’s instructions on preparing and consuming food.

Avoid contact with wild birds and sick or dead animals

If you have job-related or recreational exposure to infected animals, including wild birds, poultry, and dairy cows, you are at greater risk of being exposed to H5N1 bird flu. These jobs may include farmers or workers on poultry and dairy farms, slaughterhouse workers, backyard bird flock owners, veterinarians and veterinary staff, and emergency responders. In addition to the recommendations above, you should:

• Call your doctor if you feel sick. Symptoms of H5N1 bird flu can include cough, sore throat, fever, and red or watery eyes.
• Get your seasonal flu vaccine. Everyone - especially workers at risk for exposure to bird flu - should get 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 workers: Follow CDC recommendations to protect yourself from H5N1 bird flu at work.
• For employers: Follow all CDC recommendations for worker protection to reduce risk of infection.
• For backyard flock owners: Follow the U.S. Department of Agriculture (USDA) Defend the Flock recommendations. If you think birds in your flock may have bird flu, follow CDC recommendations to protect yourself.