Bird flu cases rise among dairy workers in California amid growing herd infections

California has six confirmed human bird flu cases and health officials suspect five more among dairy workers in the Central Valley.

The Golden State is the nation's leading producer of milk.

The state's Department of Food and Agriculture confirms bird flu in a hundred different dairies in central California. Through these infected herds, health officials say six people contracted the virus and possibly five others. None of the cases involved human-to-human transmission.

"All of our cases here in California have been workers who work very closely and have prolonged and close contact with infected dairy cattle," said state epidemiologist Dr. Erica Pan with the California Department of Public Health.

She said genetic sequence testing shows the virus isn't changing, mixing or evolving making it less likely to spread among people.

"There's not been any evidence over the last 20 years with avian or bird flu of human-to-human transmission," she said.

Those infected report flu-like symptoms including pink eye. The herds infected represent less than a tenth of the state's dairy cow population. Measures to stop the spread and to educate, test and protect workers continue.

"We at the state have been able to provide over 2 million pieces of personal protective equipment across the state, and I think over 1 million of those pieces have gone specifically to Tulare County," Pan said.

"We're gonna get in front of this. We're gonna protect our dairy workers. We're going to protect our creamery workers. We're going to protect our public," said Sean Roberts with Tulare County Public Health.

"The threat to the public is generally low," Pan said.

Milk from sick cows is not permitted into the public milk supply. Pan said to avoid raw milk, but pasteurized dairy products are safe to consume.

"If you are eating and drinking pasteurized milk and dairy products, these are safe. Pasteurization is fully effective at inactivating virus. That is why we have developed pasteurization. It also helps protect us from other bacterial infections," she said.

The risk to the general public is low. Pan said all of the people infected have recovered and didn't require a hospital stay.