On Oct. 18, 2024, the California Department of Public Health (CDPH) reported that a total of 13 human bird flu cases were confirmed in California. All 13 cases were Central Valley individuals who had direct contact with infected dairy cattle and were confirmed after additional testing by the Centers for Disease Control and Prevention (CDC).

Given the amount of exposure individuals with bird flu infections have with infected cows, evidence continued to suggest only animal-to-human spread of the virus in California. Based on CDC’s genomic sequencing of three California bird flu cases, there was no evidence to suggest an increased ability for the virus to infect or spread between people and no known reduced susceptibility to antiviral medications.

Given the amount of exposure individuals with bird flu infections have with infected cows, evidence continues to suggest only animal-to-human spread of the virus in California. Additionally, based on CDC’s genomic sequencing of three California bird flu cases, there is no evidence to suggest an increased ability for the virus to infect or spread between people and no known reduced susceptibility to antiviral medications.

All individuals have experienced mild symptoms, including eye redness or discharge (conjunctivitis), and have been treated according to CDC guidance. None of the individuals have been hospitalized

While the risk to the general public remains low, additional, sporadic human cases of bird flu are expected to be identified and confirmed in California among individuals who have regular contact with infected dairy cattle. CDPH continues to work closely with local health jurisdictions to identify, track, test, confirm and treat possible and confirmed human cases of bird flu.