Human Cases of Bird Flu Reported in California

By Tom Polansek
CHICAGO (Reuters) – California reported a third human case of bird flu on Wednesday involving a dairy worker who had contact with infected cattle. The state has identified two more potential cases in individuals with similar exposure.

Officials from the California Department of Public Health anticipate confirming additional cases among individuals in contact with infected dairy cattle, following a rise in dairy cow infections in the state.

So far this year, nearly 300 dairy herds across 14 states have tested positive for bird flu, with a significant portion of these cases emerging in California since late August, according to the U.S. Department of Agriculture. The public health department reassures that pasteurized milk and dairy products remain safe for consumption.

Nationwide, a total of 16 individuals exposed to dairy cows and poultry have tested positive in 2024, alongside one case in Missouri, unrelated to direct animal contact.

The U.S. Centers for Disease Control and Prevention (CDC) notes that human cases linked to exposure to infected animals are "not unexpected," and the overall risk to the general population remains low.

Concern over the virus's transmission to cattle and subsequent infections in farm workers has raised alarms among scientists and federal officials about potential human risks. However, California's public health department stated that there is no known link or person-to-person transmission among the confirmed or suspected cases, indicating the virus is likely spreading from animals to humans.

All affected individuals had contact with animals at different farms and reported mild symptoms such as eye redness or discharge; none required hospitalization. Last week, California recorded two human cases among dairy workers without any genetic mutations in the virus that would enhance its ability to spread among humans or affect antiviral drug susceptibility, according to the CDC.