New form of H5N1 bird flu found in US dairy cows

Photo illustration of milk samples for testing for H5N1 flu virus

This virus could 'make Covid seem like a walk in the park'

(Image credit: Photo illustration by Michael M. Santiago / Getty Images)

published 6 February 2025

What happened

The U.S. Department of Agriculture said Wednesday that a second type of H5N1 bird flu had infected U.S. dairy herds, suggesting that cattle are more susceptible to the avian virus than previously believed and putting dairy workers at greater risk.

"I always thought one bird-to-cow transmission was a very rare event," said Richard Webby, an influenza expert at St. Jude Children's Research Hospital, said to The New York Times. That it happened twice is "a little bit of a 'wow' to me." Most of the 67 people diagnosed with bird flu in the U.S. had mild symptoms and had worked with dairy or cattle, but the one known death was an elderly man infected with D1.1 after contact with wild and backyard birds.

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Peter has worked as a news and culture writer and editor at The Week since the site's launch in 2008. He covers politics, world affairs, religion and cultural currents. His journalism career began as a copy editor at a financial newswire and has included editorial positions at The New York Times Magazine, Facts on File, and Oregon State University.