Dairy cows in Nevada have been contaminated with a brand new type of chicken flu that’s distinct from the model that has been spreading by way of herds during the last yr, the U.S. Division of Agriculture introduced on Wednesday.

The discovering signifies that the virus, often called H5N1, has spilled from birds into cows not less than twice — main to those two units of infections — and that it may proceed to take action. It additionally means that the virus might pose a persistent danger to cows and to the individuals who work carefully with them.

Earlier than final yr, scientists didn’t know that cows had been prone to the sort of influenza.

“This isn’t what anybody needed to see,” mentioned Louise Moncla, an evolutionary biologist who research avian influenza on the College of Pennsylvania. “We have to now take into account the chance that cows are extra broadly prone to those viruses than we initially thought.”

The information was introduced in a information launch from the Animal and Plant Well being Inspection Service, a division of the Division of Agriculture. Federal businesses haven’t held a information briefing on chicken flu since President Trump took workplace.

The virus that has been spreading by way of the nation’s dairies is a model of H5N1 often called B3.13, which has contaminated greater than 950 herds in 16 states. Scientists imagine that it initially jumped to cows from birds a couple of yr in the past, someplace within the Texas panhandle. That transition took scientists without warning, and this new one much more so.

“I used to be form of below the assumption that the bird-to-cow motion was a fairly uncommon occasion,” mentioned Richard Webby, an influenza skilled at St. Jude Kids’s Analysis Hospital.

The truth that it has occurred once more is “a little bit little bit of a ‘wow’ to me,” he added.

The cows in Nevada had been contaminated with a model of the virus often called D1.1, which has been spreading in wild birds and poultry. It was initially detected in milk collected from a silo as a part of a nationwide milk testing technique introduced by the usD.A. late final yr.

The D1.1 type of H5N1 has additionally proven itself to be harmful to individuals. Of the 67 Individuals recognized to have change into sick with H5N1 to this point, the one one who died was contaminated with this model. That individual, a Louisiana resident older than 65, had cared for sick and dying birds and died in early January.

In November, a 13-year-old Canadian lady additionally turned contaminated with the D1.1 virus, however it’s unclear the place she may need acquired it. Her solely danger issue was weight problems, however she, too, turned critically sick and was positioned on life help due to organ failure. She finally recovered.

Avian influenza is so known as as a result of it’s best tailored to infecting birds. However in each these people, the virus gained mutations throughout the course of an infection that may permit it to raised infect individuals.

“It’s attainable that the virus is extra permissive for human adaptive mutations,” mentioned Scott Hensley, an immunologist on the College of Pennsylvania.

Reassuringly, the virus didn’t appear to unfold from both individual to anybody else. Nonetheless, its evolution indicated that it was able to gaining the power to effectively unfold amongst individuals.

To this point, not less than, the unfold of D1.1 to cows “doesn’t change the typical individual’s life,” Dr. Moncla mentioned. However it poses dangers for dairy employees and the dairy business, consultants mentioned. It additionally suggests the chance that cows already contaminated as soon as with B.3.13 may change into sick a second time with D1.1, Dr. Webby mentioned.

“It’s not only one virus,” he mentioned. “This, to me, means that it’s going to be a lingering drawback.”

Since January 2022, when H5N1 was detected in wild aquatic birds in america, the virus has affected greater than 153 million industrial, yard and wild birds, leading to file costs on eggs.

It has additionally struck dozens of mammalian species, together with cats each wild and domesticated, raccoons, bears and sea lions.