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A week after the first human cases of bird flu were announced in California, the count is up to six individuals infected with the virus.

The six people are located in the Central Valley and had direct contact with infected dairy cattle. Two of the human cases originated from the same Central Valley farm.

Last month, the California Department of Food and Agriculture reported that three unnamed Central Valley dairies had infected herds and would be placed under quarantine.

Evidence suggests only animal-to-human spread of the virus in California, according to the state Department of Public Health.

Based on genomic sequencing of California’s first two human bird flu cases by the Centers for Disease Control and Prevention, there have been no genetic changes observed to suggest an increased ability for the virus to infect or spread between people and no known reduced susceptibility to antiviral medications.

In addition to the six confirmed cases, CDPH has also been notified of one additional possible human case, also in the Central Valley. That specimen has been sent to CDC for confirmatory testing.

All six individuals with confirmed cases of bird flu have experienced mild symptoms, including eye redness or discharge (conjunctivitis). All have been treated according to CDC guidance and none of the individuals have been hospitalized.

California is the latest of 14 total states reporting outbreaks of bird flu in cattle. The disease was first detected in U.S. poultry in 2022.