A dairy farm worker in California’s Central Valley with mild symptoms tested positive for the bird flu virus — the first case in the state and the 16th in the nation this year — said the California Department of Public Health on Thursday. The worker was being treated with antiviral medication and was staying home to recover.
Officials said the worker, who was not identified, was employed at a dairy farm that was dealing with an outbreak of bird flu among its milk cows and had contact with the animals. California is the No. 1 milk-producing state in the country and home to 55 — or more than one-fifth — of the 255 infected herds in 14 states.
“Fortunately, as we’ve seen in other states with human infections, the individual has experienced mild symptoms,” said Dr. Tomás Aragón, director of the state’s public health department. The symptoms were reported as conjunctivitis, also called pink eye.
Tests by a local health department showed a “presumptive positive” for infection by the H5N1 avian flu virus, said the state health department. Samples were sent to the Centers for Disease Control for confirmation.
“We want to emphasize that the risk to the general public is low, and people who interact with potentially infected animals should take prevention measures,” said Aragón. State and federal public health officials recommend the use of protective gear, such as masks, goggles, and gloves, by people in contact with infected or potentially infected animals.
The California worker was first human infected in the state since bird flu was detected in dairy herds in the Central Valley on Aug. 30, and the first in the nation in a month. All of the other illnesses involved poultry and dairy workers except for a Sept. 6 case in Missouri in which the patient had no known contact with animals.
Five healthcare workers developed mild respiratory symptoms while treating the Missouri patient, who has recovered. The CDC said it would test blood samples from the workers for the avian flu virus. The development of symptoms raised the possibility of the first known person-to-person spread of the H5N1 virus.
Bird flu was confirmed in 12 California dairy herds this week, according to a USDA database. The viral disease was identified in late March as the mystery disease affecting dairy herds in Texas, the first time the virus had jumped to cattle from birds. Highly pathogenic avian influenza has killed more than 100 million birds in domestic flocks since February 2022, mostly egg-laying hens and turkeys being raised for meat.