Confirming the dangers of drinking raw cow's milk when the H5N1 avian flu virus is circulating in U.S. dairy herds, researchers found that mice fed the milk quickly got ill.
"Our data indicate that HPAI A[H5N1] virus in untreated milk can infect susceptible animals that consume it," concluded a team led by virologist Yoshihiro Kawaoka, of the University of Wisconsin–Madison. His team published the findings Friday in the New England Journal of Medicine . In late March, researchers first detected traces of H5N1 bird flu in nasal swabs and milk obtained from U.
S. dairy cows. Since then, the outbreak has been detected in many dairy herds across multiple states.
So far, H5N1 does not seem to transmit easily between animals and humans: There have been only two known human cases of H5N1 infection linked to the U.S. dairy cow outbreak.
Both have occurred in dairy workers who have had extended, close contact with the animals. Experts also believe the general milk supply to be safe, since the heating involved in pasteurization kills the virus. However, drinking unpasteurized "raw" milk—a craze among a small subset of consumers—may, in fact, run the risk of passing H5N1 to other mammals, including people.
To find out if that is true, Kawaoka and his team gave mice raw cow's milk known to be contaminated with the H5N1 virus. The rodents received the milk by mouth. The mice showed typical signs of infection, such as "ruffled fur and lethargy" as soon as one day after being fed the m.
