By Kerry Klein
Avian influenza has now infected cattle at more than 700 of California’s dairies. That encompasses the vast majority of farms that make up the state’s $8-billion-a-year dairy industry. But when it comes to non-dairy cattle, zero have tested positive in California.
KVPR asked California State Veterinarian Dr. Annette Jones how many cattle that are cultivated for meat have been infected. “None that I'm aware of,” she said Friday.
The reason behind the disparity is one of many unanswered questions about the virus–and an area where research is ongoing. Understanding why some cattle get infected and others don’t could provide a better understanding of the virus’s behavior and severity.
The virus has infected thousands of dairy cows across the country. One Tulare County dairyman told KVPR that on the worst day of his farm’s outbreak, roughly 500 of his cattle were in treatment for the virus. Nationwide, bird flu has also been detected in dozens of other mammal species, including foxes, bears, bobcats, a herd of swine in Oregon, and even some marine mammals including harbor seals and dolphins.
And yet the virus has steered clear of non-dairy breeds of cattle, even when they’ve been exposed to infected dairy cows at the same feed yard, Jones said.
“Not only are we not getting positive samples, but we're also not seeing symptoms” in those herds, Jones said.
The virus appears to spread mostly in milk, but even lactating mothers and calves appear virus-free in non-dairy herds. Plus, Jones says it’s not unheard of for different animal breeds to respond variably to viruses.
“There does seem to be some resistance in those beef breeds,” she said.
State officials hope a ban on dairy cattle shows is temporary
Avian influenza began ravaging bird populations in 2022 before being detected in dairy cattle in Texas last year. The first positive test in California cattle occurred in late August.
The virus has also been confirmed in 67 people in the U.S., most of whom encountered the virus through contact with infected cattle or birds. Although most cases have been mild, a Louisiana resident died of bird flu earlier this month, and health officials warn the virus could become more severe if it begins spreading between humans. A new case of bird flu in a child was also revealed on Thursday.
To free up resources to help contain the virus, California Gov. Gavin Newsom declared a State of Emergency related to bird flu in December.
Then, earlier this month, Jones and the California Department of Food and Agriculture prohibited fairs and exhibitions of dairy cattle and poultry.
“Due to the continued spread of H5N1 bird flu in California, the state veterinarian has implemented a ban on all California poultry and dairy cattle exhibitions at fairs and shows immediately until further notice,” the Jan. 8 notice reads. “This action is required to minimize the danger of exposing people and non-infected cows and birds to the disease.”
Shows involving other livestock, however, are permitted to continue. According to Jones, that’s because these events are also considered an education tool.
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