Raw Milk Containing Bird-Flu Virus Can Sicken Mice, Study Finds

Unpasteurized milk contaminated with H5N1, the bird-flu virus that has turned up in dairy herds in nine states, has been found to rapidly make mice sick, affecting multiple organs, according to a study published on Friday.

The findings are not entirely surprising: At least a half-dozen cats have died after consuming raw milk containing the virus. But the new data add to evidence that virus-laden raw milk may be unsafe for other mammals, including humans.

“Don’t drink raw milk — that’s the message,” said Yoshihiro Kawaoka, a virologist at the University of Wisconsin, Madison, who led the study.

Most commercial milk in the United States is pasteurized. The Food and Drug Administration has found traces of the virus in 20 percent of dairy products sampled from grocery shelves nationwide. Officials have not found signs of infectious virus in those samples and have said that pasteurized milk is safe to consume.

But the findings have global implications, said Dr. Nahid Bhadelia, director of the Boston University Center on Emerging Infectious Diseases, who was not involved in the work.

“If this becomes a more widespread outbreak in cows, there are other places where there isn’t central pasteurization,” she cautioned, “and there are a lot more rural communities that drink milk.”