With bird flu spreading to cattle in nine states, Marin County health and agriculture officials are stepping up surveillance efforts to be prepared in case the virus appears in California livestock.
The H5N1 virus made the jump from birds to cattle in late March, and three cases have since been reported in dairy workers, the latest in Michigan. No cases have been reported in livestock in California, but Marin officials want to be ready if any occur.
For now, testing of cattle in Marin is voluntary. But the state is encouraging farms to step up biosecurity measures and is making available free personal protective equipment to ranchers and dairies that request it. County agriculture officials are increasing communication with West Marin farmers to make them aware of new state and federal measures that can provide support if their animals become infected.
The current strain of bird flu has caused only mild symptoms in humans, and the Centers for Disease Control and Prevention says that the risk to the public is low. But late last month, Marin’s Division of Public Health began weekly testing of wastewater to check for the presence of H5N1. So far, no tests have come back positive. The county was already testing wastewater for a variety of other viruses, including Covid-19 and R.S.V.
“We are not sounding an alarm regarding H5N1 for the general public,” said Dr. Matt Willis, Marin’s public health officer. “At the same time, we know that with a few shifts in the virus, it could gain virulence and become more easily transmitted, so we need to make sure our monitoring systems are strong and that we’re able to react.”
The most recent human case of bird flu in a dairy worker heightened concern among public officials. The first two cases, reported in Texas, resulted in eye infections for those who had been exposed. But the third case, which occurred in Michigan, caused respiratory symptoms, increasing the risk of spreading the virus from person to person.
State and county officials are encouraging ranchers and dairy farmers to isolate any cows that appear to be sick and send a milk sample to a federally certified lab for testing.
“Even though it poses a low risk to our residents, and it is not known to cause mortality in cattle, I’m certainly concerned about H5N1 because finding it in Marin would cause undue hardship to our ranchers from a production and P.R. standpoint,” said Scott Wise, Marin’s deputy agriculture commissioner. “Agriculture is struggling in Marin, and frankly, it’s the last thing anyone needs right now.”
Mr. Wise said the county is stepping up communication with Marin ranchers and dairy farmers, making them aware of new federal supports for farms and incentives to report and test sick cows.
In April, the United States Department of Agriculture issued an order limiting the movement of lactating dairy cattle across state lines. And last month, the Biden administration pledged nearly $200 million in new spending to track and contain the spread of bird flu in cows.
The funds will help cover the cost of a range of protective measures, including the testing of herds, the pasteurization of milk and the purchase of personal protective equipment for dairy workers. It can also be used to reimburse farmers who lose cattle to the virus.
The measures were welcomed by Marshall dairyman Albert Straus, president and C.E.O. of Straus Family Creamery, who said they were the appropriate steps to protect the health of California herds at this stage.
So far, the 13 dairies in West Marin and Sonoma County that supply his company have not tested their herds or their workers. “All our products have been pasteurized, and it’s been found that pasteurization kills the virus,” he said.
Although pasteurized milk is safe, raw milk can carry the virus, according to Dr. Willis.
“Raw milk has actually been making it into our grocery stores as part of our regional milk marketplace,” he said. “Several of our retailers in Marin County do stock raw milk on their shelves.”
Cows are believed to become infected with the virus after their feed or water is contaminated with the feces or saliva of wild birds. And exposed cows may be passing the virus to others through airborne transmission.
While the virus is usually fatal in poultry, infected cows typically recover within 10 to 14 days. So far, only a few cows have reportedly died of H5N1.
In December and January, bird flu outbreaks hit 11 commercial poultry farms in Sonoma, and one in Marin. To prevent further spread, 1.2 million birds were euthanized in Sonoma, and 150,000 were culled in Marin, causing more than $20 million in losses for the region’s farmers.
Dr. Willis said increased vigilance will lower the chances of a fatal outbreak in cattle.
“This is a period of uncertainty, and we don’t want to alarm people or offer false reassurance,” he said.