AP – Dairy cattle in Nevada, United States (US) 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.
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. 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 influenza expert at St Jude Children’s Research Hospital Richard Webby.
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, 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 virus expert at the University of Saskatchewan in Canada Angela Rasmussen, 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 Centres for Disease Control and Prevention.
