H5N1 Bird Flu in Dairy Cows

Last content update: 5/24/24        

The County of Santa Clara Public Health Department is monitoring a multi-state outbreak of H5N1 bird flu in dairy cows in the United States. This is the first time that H5N1 bird flu has been found in cows. As of May 22, 2024, the state has indicated that there are no reported cases of H5N1 bird flu in cows or humans in California. The current risk to the general public from H5N1 bird flu is low. 

For more information including the number of reported human H5N1 cases in the United States, visit the CDC’s Current H5N1 Bird Flu Situation in Dairy Cows webpage.

What is H5N1 bird flu?

H5N1 bird flu is a specific strain or type of influenza virus. H5N1 bird flu is also called highly pathogenic avian influenza (HPAI). H5N1 bird flu can infect wild birds, poultry, and mammals such as cows. Human infections with H5N1 bird flu are rare, but spread of the virus may lead to changes that make it more likely to infect humans.

What is the Public Health Department doing?

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.

No H5N1 bird flu has been detected in wastewater in Santa Clara County. For data on the level of flu viruses detected in wastewater in Santa Clara County, refer to the Influenza and RSV Report dashboard. This dashboard indicates the level of flu virus particles present in wastewater, but does not indicate what type(s) of flu viruses are present or how the virus was introduced into the wastewater. In response to recent wastewater flu activity in the Gilroy sewershed, the Public Health Department has obtained further wastewater testing and no H5N1 bird flu was detected in samples from that sewershed between February 2, 2024, and May 6, 2024.

What can you do?

CDC has indicated that the current risk to the general public from H5N1 bird flu is low. People should follow these recommendations:

  • Do not 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.
  • Avoid unprotected exposures to sick or dead animals including wild birds, poultry, and other domesticated birds. Handling sick or dead animals safely requires personal protective equipment and training.

People who have job-related or recreational exposure to infected animals, including wild birds, poultry, and dairy cows, are at greater risk of being exposed to H5N1 bird flu. These people 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, these people should also:

  • Follow all CDC recommendations for worker protection to reduce risk of infection.
  • Call your doctor if you feel sick. Symptoms of H5N1 bird flu can include cough, sore throat, fever, and red or watery eyes.

Need a doctor or health insurance? Call the County's Patient Access Department at 1 (866) 967-4677 or drop in at 770 S. Bascom Ave. San Jose, CA 95128.

Learn more

For more information on H5N1 bird flu, refer to the CDC’s Current H5N1 Bird Flu Situation in Dairy Cows webpage.

Educational flyer for agricultural workers

The Public Health Department has also created this educational flyer for agricultural workers about H5N1 bird flu. Please access the PDF below:


Additional resources


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