Bird flu virus was found in raw milk. What to know about the risks

President-elect Donald Trump’s nominee for the nation’s top health job, Robert F. Kennedy Jr., has vowed to allow wider distribution of raw milk across America. But the detection of bird flu virus in unpasteurized milk sold in California stores underscores what health experts say are the known and potential risks.

“You have to assume that raw milk, unpasteurized milk, has potential infectious agents that can cause serious illness in the people who drink it,” said Michael Osterholm, a University of Minnesota infectious disease researcher who has investigated foodborne illness outbreaks.

Raw Farm LLC, of Fresno, California, voluntarily recalled one lot of “cream top” whole raw milk after Santa Clara County health officials found the bird flu virus in a sample last week. State health officials said the county has been testing raw milk sold in stores as “a second line of consumer protection.”

No illnesses have been traced to Raw Farm products, which have a lot code of 20241109 and a best-by date of Nov. 27. But officials with California’s health department warned consumers not to drink the milk and said retailers should remove it from their shelves. On Tuesday, Los Angeles County health officials warned that “many retailers” there may have sold recalled raw milk contaminated with the virus.

Here’s what else you need to know about raw milk and bird flu:

It’s not a surprise that the virus was found in raw milk sold in stores, Osterholm said.

Bird flu, also known as Type A H5N1 influenza, was first confirmed in U.S. dairy cattle in March and has been spreading widely. In California, more than 435 dairy herds have seen infections — more than all other U.S. states combined. And high levels of the virus have been found in the milk of infected cows.

About 20% of samples of pasteurized milk sold in stores were found to contain viral remnants of the virus, according to tests conducted earlier this year by government scientists. Pasteurization, or heat treatment, kills the bird flu virus and also bacteria such as E. coli, listeria and salmonella, which are known to make people sick.

Officials with California’s Department of Food and Agriculture have been conducting weekly tests of raw milk in bulk tanks from the state’s dairies. Additional tests conducted at Raw Farm sites in California were negative for the virus, but officials said they would begin testing for bird flu twice a week.

Few tests of unpasteurized milk products from stores have been…