Bird flu is a disease caused by avian influenza A viruses, according to the CDC. The virus mostly spreads between birds and dairy cows, but there have been 67 human cases of bird flu nationwide and one death tied to the infection since 2024, CDC records show.

On Thursday, the U.S. Centers for Disease Control and Prevention confirmed another case of avian influenza A(H5N1), or bird flu, in California, bringing the nationwide total of cases to 67.

A new strain of bird flu has been confirmed at a duck farm in California, the first time the variant has been discovered in poultry in the United States, an international agency said.