New form of H5N1 bird flu found in US dairy cows

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.

Who said what

The new H5N1 version, known as D1.1, was found in dairy cattle in Nevada and is different than the B3.13 type that has spread to more than 950 herds in 16 states over the past year, starting in Texas. The D1.1 infection was discovered by testing raw milk under a USDA dairy surveillance project launched last year.

"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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What next?

"There does not appear to be an immediate change to human risk," already considered low for the general public, The Washington Post said. But it's important for federal officials to be vigilant and transparent about a virus that could "make Covid seem like a walk in the park," said Michael Worobey, a University of Arizona evolutionary biologist.