Drinking raw milk containing bird flu viruses may be dangerous: Study
Study shows bird flu virus in raw milk poses consumer risks.
Mice fed raw cow’s milk infected with bird flu had high virus levels in their lungs, according to a study published on Friday. This finding raises concerns about the risks to humans who drink raw milk.
In recent years, the highly contagious bird flu virus, HPAI H5N1, has spread to more than 50 animal species. Since March, it has also infected dairy cattle in the United States. So far, 52 herds have been affected, and two farm workers developed mild symptoms, including pink eye, after exposure.
In the new study, researchers from the University of Wisconsin-Madison and Texas A&M fed raw milk from infected cows to five mice. The mice showed signs of illness like lethargy and were euthanized four days later to examine their organs. The scientists found high levels of the virus in the mice’s nasal passages, trachea, and lungs.
“An important consideration is that the consumption of raw, unpasteurized milk is becoming increasingly popular,” said Rowland Kao, a professor of veterinary epidemiology at the University of Edinburgh, who was not involved in the research.
Raw milk laws in the U.S. differ by state. Some states allow its sale in stores, some permit it only on farms, and others ban it completely. A 2019 survey showed that 4.4% of adults had consumed raw milk in the past year, mostly younger people in rural areas.
“While this study shows that mice can become systemically infected due to ingesting infected milk, this does not prove that the same is true for humans, though it does increase the possibility,” added Kao.
The study also found that heating raw milk to high temperatures for a few seconds destroys almost all the virus, and destroys it after several minutes. Pasteurized milk samples from a nationwide survey were negative for viable virus, though inactivated virus was found in about 20% of retail samples. Storing raw milk in the fridge for five weeks slightly reduced virus levels, but not enough to make it safe.
The findings suggest caution for those consuming raw milk, highlighting the importance of pasteurization to kill harmful pathogens.
