Drinking raw milk at any time is flirting with dangerous germs. But amid an unprecedented outbreak of H5N1 bird flu in American dairy cows, the risks have risen sharply. Health experts have stepped up warnings against consuming raw milk during the outbreak, the extent of which is still unknown.
However, raw milk enthusiasts are not deterred by the increased risk. The California-based Raw Milk Institute called the warnings “clearly alarmist“The institute’s founder, Mark McAfee, told the Los Angeles Times this weekend that his clients are, in fact, specifically request raw milk from cows infected with H5N1. According to McAfee, his clients believe, without evidence, that directly drinking high levels of the avian influenza virus will give them immunity against 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 UC Davis’ Western Institute for Food Safety, added: “Deliberately trying to become infected with a known pathogen goes against all medical knowledge and common sense.”
There is still much to know about the biology of avian influenza in cattle. Until March 25, when the U.S. Department of Agriculture confirmed the virus in a Texas dairy herd, cattle were generally considered virtually resistant to H5N1. But since then, the USDA has accounted 42 herds in nine states who have contracted the virus. Epidemiological data so far suggest that there has been cow-to-cow transmission after a single infection event and that the 42 herds in the outbreak are connected by the movement of livestock between farms.
The limited data on cows so far suggest that the animals largely develop mild illness from the infection and recover within a few weeks. Your mammary glands are the main target of the virus. A preprint published earlier this month. discovered that cows’ udders are riddled with molecular receptors to which bird flu viruses attach to cause infection. Additionally, the glands contain multiple types of receptors, including those targeted by human flu viruses and those targeted by avian flu viruses. Dairy cows could therefore act as a mixing vessel for different types of flu viruses to reassemble into new variants that cause outbreaks.
Since the virus is apparently having a field day in cows’ udders, researchers have discovered that raw milk is packed with high levels of H5N1 viral particles, and those particles seem easily capable of infecting other mammals. In a case study last month, researchers reported that a group of about two dozen farm cats developed severe illness after drinking milk from cows infected with H5N1. Some developed severe neurological symptoms. More than half of the cats died within days.
deadly virus
Data on flu receptors in the two animals may explain the difference between cows and cats. While the cow’s mammary gland had many multiple types of flu receptors, those receptors were less common in other parts of the cow, including the respiratory tract and brain. This may explain why they tend to have a mild infection. Cats, on the other hand, appear to have more widely distributed receptors, and infected cats show viral invasion of the lungs, hearts, eyes and brains.
Raw milk devotees, who claim without evidence that drinking raw milk provides health benefits compared to drinking pasteurized milk, dismiss the risk of H5N1 exposure. They confidently argue, also without evidence, that the human digestive system will destroy the virus. And they highlight that there is no documented evidence that a human being has become infected with H5N1 by drinking contaminated milk.
The last point about the lack of evidence of H5N1 transmission through milk is true. However, the current outbreak is the first known spread of highly pathogenic avian influenza (HPAI) to the mammary glands of dairy cows. As such, it presents the first known opportunity for such transmission through milk to occur.