California investigates possible case of bird flu in dairy farmer

California is investigating a possible case of bird flu in a dairy worker who had contact with infected cattle, the state’s public health department said Thursday.

The virus’s jump to livestock in 14 states and infections of 13 dairy and poultry workers this year have scientists and federal officials concerned about the risks to humans from further spread.

The worker had a “presumptive positive” result on a test for bird flu, and the U.S. Centers for Disease Control and Prevention will conduct further testing to confirm the finding, the California Department of Public Health said in a statement.

The person, who was not identified, suffered only from conjunctivitis or pink eye, the department said in a statement. The person is being treated with antiviral drugs and remains at home, it added.

According to the statement, the person works at a Central Valley dairy farm that is experiencing an outbreak among livestock.

Cows on dairy farms in California, the largest milk-producing state in the US, began testing positive for bird flu in late August.

“The risk to the general public remains low, although people who have contact with infected animals are at greater risk of contracting bird flu,” the department said.

Missouri last month confirmed bird flu in a person with underlying medical conditions and no known direct exposure to animals. Six health care workers who cared for the Missouri patient developed respiratory symptoms, but none were confirmed to have the virus.

Scientists are watching closely for signs that the virus is starting to spread more easily among people.

The U.S. Food and Drug Administration said Thursday it will begin testing raw cow’s milk destined for pasteurization in dairies to better understand the prevalence of the bird flu virus in milk.

Participation in the study, which starts Oct. 28, is voluntary and pasteurized dairy products remain safe to consume, the agency said.

Previous FDA testing of retail dairy samples came back negative, and more such tests are underway.