2 dairy workers infected with bird flu in California’s 1st human cases

Two dairy workers in California were infected with bird flu, the 15th and 16th human cases detected this year in an ongoing outbreak affecting the nation’s dairy cows, health officials said Thursday.
The latest cases were found in workers who had contact with infected cattle in California’s Central Valley, where more than 50 herds have been affected since August. The workers developed eye redness known as conjunctivitis and had mild symptoms.
California health officials said the workers were employed at different farms and there is no known link between the two cases, suggesting that they were infected through animal contact, not by people.
The U.S. Centers for Disease Control and Prevention on Thursday confirmed the positive test results, the first for California. CDC officials said new cases of bird flu in people exposed to infected animals is “not unexpected.” The risk to the public remains low, they added.
“The good side is, it’s very low risk still to the general public,” said Dr. Peter Chin-Hong, an infectious disease expert at UCSF. “The bad side is, every time there’s a transmission event, that’s a chance for the virus to evolve.”
Although the seasonal flu shot doesn’t protect against bird flu, Chin-Hong urges people get vaccinated as it may make it harder for the virus to mutate.
“So, if bird flu gets into somebody who has regular human influenza, they can swap genes and make a mutant that can be more serious for the general population,” he said.
Across the U.S., more than 250 dairy herds have been infected in 14 states since the outbreak of H5N1 avian influenza was confirmed in March. Avian influenza has been spreading in wild and domestic birds in the U.S. for several years but recently was found in dairy cows.
Before this year, one case of bird flu was detected in a person, a Colorado poultry worker who fell ill in 2022. Most cases this year have been detected in workers who had contact with cattle or poultry in Colorado, Michigan and Texas. A person in Missouri was also infected, but that person had no known contact with animals and the source of that illness has not been determined.
“It’s called bird flu because its sweet spot of infection is wild birds. In fact, there’s a pandemic right now among wild birds and geese. But, it’s crossing over to mammals. It hasn’t crossed all the way over to humans yet. The reason why we’re worried about bird flu is that humans haven’t really seen a lot of it. When they do, their antibodies are not equipped to deal with it,” Chin-Hong said. “It’s very low risk to the general population at this point. But, in the big picture, we have to worry about emerging pandemics and be very curious, but not panicked, by it.”  
While the risk to the general public remains low, Chin-Hong said people can take simple steps to protect themselves.
“Be very careful around raw milk, unpasteurized milk, that’s really where you can get infected as a human more recently,” he said.