That’s not always the case, but under normal circumstances, “if a producer follows strict sanitation protocols and good manufacturing processes, the risk of getting sick from raw-milk cheese is low,” says Adam Brock, administrator of the division of food and recreational safety in the Wisconsin department of agriculture, trade, and consumer protection. In 2016, the FDA tested 1,600 samples of raw-milk cheeses for salmonella, listeria, and E. coli and found less than 1 percent of the samples to be contaminated. Most of the contaminated cheeses were semisoft types, such as Fontina, or soft-ripened cheeses, such as Brie. Hard cheeses, such as cheddar and manchego, fared better, but there were still some contaminated samples.
Avian flu has raised new questions about the risk though. FDA tests found that the live virus is not present in pasteurized milk (which is heated to kill germs), so cheese made from pasteurized milk is safe. However, recent research in the New England Journal of Medicine found that mice given raw milk from infected cows became ill with the virus. And a study in the journal Emerging Infectious Diseases found that cats living on a farm with infected cows died from the virus, and that drinking raw milk was their likely route of exposure.
Flu viruses typically spread among people not through food but via tiny droplets released when people talk, cough, or sneeze. No one knows whether drinking contaminated raw milk would spread the virus to people, but these studies show it’s theoretically possible. And it isn’t known whether the aging process that the FDA requires for raw-milk cheeses in the U.S. would kill or inactivate the avian flu virus.
“I strongly recommend people avoid drinking raw milk, and given the uncertainties, I would advise people to avoid raw-milk cheeses, too, until we know for certain that raw-milk cheeses can’t be a vehicle for transmitting live infectious virus to people,” says James E. Rogers, PhD, director of food safety and testing at Consumer Reports.
