Health officials in California are investigating a possible third human case of bird flu, the California Department of Public Health announced Saturday.

Both patients were dairy workers whose illnesses were mild. Investigators are continuing to evaluate the contacts of a Missouri patient who had no exposure to animals.

Although California dairy farmers anticipated a bird flu mortality rate of less than 2%, some say between 10% and 15% of infected cattle are dying.

The two bird flu cases in California bring the total to 16 cases in the U.S. in 2024, according to the Centers for Disease Control and Prevention.

Two dairy workers in California were infected with bird flu, the 15th and 16th human cases detected in the U.S. this year.

Local health officials have confirmed that two dairy workers infected with the avian bird flu got sick while working in the Tulare County dairy industry.

The workers had been in contact with infected cattle in the US, bringing the total number of cases this year to 16.

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.

Federal officials plan to double the stockpile of emergency bird flu vaccines as they identify more people infected with the disease. Three manufacturers were awarded $72 million to increase pandemic preparedness including against avian influenza,

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