The Centers for Disease Control and Prevention (CDC) has confirmed two human cases of H5 bird flu from specimens submitted by California.
The cases occurred in people with occupational exposure to infected dairy cows. An investigation led by California is ongoing. The identification of H5 in people with exposure to infected animals is not unexpected and does not change CDC's risk assessment for the general public, which continues to be low.
At this time, there is no known link or contact between the first and second confirmed cases in California, suggesting these are separate instances of animal-to-human spread of the virus.
These are the first human cases of H5 in California, where H5N1 outbreaks among dairy herds were first reported in August 2024. Including this most recent case, 16 human cases of H5 have been reported in the United States during 2024, bringing the total to 17 cases since 2022. CDC recently issued updated personal protective equipment guidance (PPE) to prevent H5N1 bird flu infection.
