New type of bird flu detected in US dairy cows

The new version, known as D1.1, was confirmed in Nevada cattle and was linked to the first US death tied to bird flu

Carson City: Dairy cattle in Nevada have been infected with a new type of bird flu that’s different from the version that has spread in US herds since last year, Agriculture Department officials said on Wednesday.

The detection indicates that distinct forms of the virus known as Type A H5N1 have spilled over from wild birds into cattle at least twice.

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Experts said it raises new questions about wider spread and the difficulty of controlling infections in animals and the people who work closely with them.

“I always thought one bird-to-cow transmission was a very rare event. Seems that may not be the case,” said Richard Webby, an influenza expert at St Jude Children’s Research Hospital.

A version of the H5N1 bird flu virus known as B3.13 was confirmed in March after being introduced to cattle in late 2023, scientists said. It has infected more than 950 herds in 16 States.

The new version, known as D1.1, was confirmed in Nevada cattle on Friday, according to USDA. It was detected in milk collected as part of a surveillance programme launched in December.

“Now we know why it’s really important to test and continue testing,” said Angela Rasmussen, a virus expert at the University of Saskatchewan in Canada, who helped identify the first spillover.

The D1.1 version of the virus was the type linked to the first US death tied to bird flu and a severe illness in Canada. A person in Louisiana died in January after developing severe respiratory symptoms following contact with wild and backyard birds.

In British Columbia, a teen girl was hospitalised for months with a virus traced to poultry. At least 67 people in the US have been infected with bird flu, mostly those who work closely with dairy or cattle, according to the US Centers for Disease Control and Prevention.

USDA officials said they would post genetic sequences and other information about the new form of the virus to a public repository later this week. Scientists said that would be key to understanding whether the spillover was a recent event or whether the virus has been circulating, perhaps widely, for longer.