A study from Kansas State University has revealed new insights into how the H5N1 “bird flu” influenza virus spreads among dairy cattle. This research comes at a critical time, as the virus has affected over 200 dairy farms across 14 states since its first detection in the U.S. in spring 2024.
Published in the journal Nature, the study was led by Dr. Juergen Richt, a distinguished professor at Kansas State’s College of Veterinary Medicine. Dr. Richt and his team, collaborating with German researchers, conducted experiments on both calves and lactating cows to understand how the virus transmits.
The findings paint a clear picture: milking practices appear to be the primary culprit in spreading the virus, rather than respiratory transmission. When researchers infected the mammary glands of dairy cows with the H5N1 virus, the animals developed severe symptoms including fever, mastitis (inflammation of the udder), and a sharp drop in milk production. The virus was found in high concentrations in the cows’ milk.
In contrast, calves infected through the nose and mouth showed only mild symptoms and did not spread the virus to other calves housed with them. This difference suggests that the milking process itself may be the key factor in transmission between cows.
The implications of this research are significant for the U.S. dairy industry, which includes nearly 10 million dairy cows. With the potential for economic damage and risks to human health, the study underscores the urgent need for safe and sanitary milking procedures.
According to kwch.com, Richt stressed that “if people like to drink raw milk, this milk could be contaminated with this virus” and “It’s obviously a risk to drink raw milk right now.” Given that risk, Richt recommended that people should only drink pasteurized milk. In April, the U.S. Food and Drug Administration (FDA) affirmed the safety of the country’s milk supply after bird flu traces were discovered in dairy cattle.
However, Richt emphasized the importance of studying how this new zoonotic disease spreads in dairy cows, given the potential consequences for both animal and human health.
Commenting on this article, one national food poisoning lawyer said, “Although the dairy industry is still grappling with this new threat, these findings provide a vital roadmap to limit the spread of bird flu among dairy cattle.”
