California, the biggest U.S. milk-producing state, on Thursday confirmed two human cases of bird flu in people who had contact with dairy cattle infected by the virus.

Health officials in California are monitoring other exposed workers for symptoms on two dairy farms where two human cases of bird flu were confirmed on Thursday, the U.S. Centers for Disease Control and Prevention said.

Both people had mild symptoms. The main symptom in both cases was red eyes, or conjunctivitis, a sign that a person has been infected through their eyes. Health officials say the risk to the