The U.S. Centers for Disease Control and Prevention this week confirmed two human cases of H5N1 bird flu in California. Both people were in close contact with infected dairy cows, but in separate farms. And while both had mild symptoms – conjunctivitis (pink eye) only, no respiratory symptoms – neither was hospitalized.
These are the first human cases of H5 in California, where H5N1 outbreaks among dairy herds were first reported in August. “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,” CDC wrote on its website.
After decimating chicken flocks since 2022, H5N1 bird flu was detected for the first time in U.S. cows earlier this year. CDC called the spread to humans “rare, sporadic.” Including these two cases, 16 human cases have been reported in the U.S. this year, bringing the total to 17 cases since 2022.
Cases during 2024 have been reported in Texas (1), Michigan (2), Colorado (10), Missouri (1) and California (2). Six of the 16 reported human cases have been linked to exposure to sick or infected dairy cows. Nine cases had exposure to infected poultry. The source of infection for the one case in Missouri has not been determined.
“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,” the agency said.
Reuters reported the FDA said it will soon launch a study of raw cow’s milk at some dairy plants to better understand the prevalence of the bird flu virus in the milk supply.