Enlarge / Fresh raw milk being poured into a container on a dairy farm on July 29, 2023, in De Lutte, Netherlands. (credit: Getty | Pierre Crom)

Despite the delusions of the raw milk crowd, drinking unpasteurized milk brimming with infectious avian H5N1 influenza virus is a very bad idea, according to freshly squeezed data published Friday in the New England Journal of Medicine.

Researchers at the University of Wisconsin-Madison squirted raw H5N1-containing milk from infected cows into the throats of anesthetized laboratory mice, finding that the virus caused systemic infections after the mice were observed swallowing the dose. The illnesses began quickly, with symptoms of lethargy and ruffled fur starting on day 1. On day 4, the animals were euthanized to prevent extended suffering. Subsequent analysis found that the mice had high levels of H5N1 bird flu virus in their respiratory tracts, as well their hearts, kidneys, spleens, livers, mammary glands, and brains.

"Collectively, our data indicate that HPAI [Highly Pathogenic Avian Influenza] A(H5N1) virus in untreated milk can infect susceptible animals that consume it," the researchers concluded. The researchers also found that raw milk containing H5N1 can remain infectious for weeks when stored at refrigerator temperatures.

Enlarge / A glass of fresh raw milk in the hand of a farmer. (credit: Getty | Pierre Crom)

To drink raw milk at any time is to flirt with dangerous germs. But, amid an unprecedented outbreak of H5N1 bird flu in US dairy cows, the risks have ratcheted up considerably. Health experts have stepped up warnings against drinking raw milk during the outbreak, the scope of which is still unknown.

Yet, raw milk enthusiasts are undaunted by the heightened risk. The California-based Raw Milk Institute called the warnings "clearly fearmongering." The institute's founder, Mark McAfee, told the Los Angeles Times this weekend that his customers are, in fact, specifically requesting raw milk from H5N1-infected cows. According to McAfee, his customers believe, without evidence, that directly drinking high levels of the avian influenza virus will give them immunity to the deadly pathogen.

Expert Michael Payne told the LA Times that the idea amounts to "playing Russian roulette with your health." Payne, a researcher and dairy outreach coordinator at the Western Institute for Food Safety and Security at UC Davis, added, "Deliberately trying to infect yourself with a known pathogen flies in the face of all medical knowledge and common sense."