New strain of bird flu is detected in a Nevada dairy worker, CDC says

[February 11, 2025]  By MIKE STOBBE and JONEL ALECCIA

NEW YORK (AP) — A dairy worker in Nevada was infected with a new type of bird flu that’s different from the version that has been spreading in U.S. herds since last year, federal health officials said Monday.

The illness was considered mild. The person's main symptom was eye redness and irritation, similar to most bird flu cases associated with dairy cows. The person wasn't hospitalized and has recovered, according to the Centers for Disease Control and Prevention.

The newer strain had been seen before in more than a dozen people exposed to poultry, but this is the first time an infection was traced to a cow. The Nevada dairy worker was exposed at a farm in Churchill County, in the west central part of the state, state health officials said.

CDC officials said there is no evidence the virus has spread from this person to any other people. The agency continues to say the virus poses a low risk to the general public.

The bird flu currently spreading through animals, and some people, is known to scientists as Type A H5N1 influenza. But there are different strains.

A version known as B3.13 was confirmed in March after spreading to cattle in late 2023, scientists said. It has infected 962 cattle herds in 16 states, the vast majority of them in California.

The newer version, known as D1.1, was confirmed in Nevada cattle on Jan. 31. It was found in milk collected as part of a monitoring program started in December.

That discovery meant distinct forms of the virus spread from wild birds into cattle at least twice. Experts said it raises questions about wider spread and the difficulty of controlling infections in animals and the people who work with them.

At least 68 people in the U.S. have been reported infected with bird flu in the last year, according to CDC data. All but a small handful worked closely with cows or poultry.

Most caught the B3.13 version. The CDC previously said the D1.1 version had been seen only in cases in Louisiana and Washington state. But on Monday, the agency revealed that available data indicates D1.1 last year likely infected a total of 15 people in five states — Iowa, Louisiana, Oregon, Washington and Wisconsin — all related to poultry.

The D1.1 version of the virus was linked to the first U.S. death tied to bird flu and to 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 hospitalized for months with a virus traced to poultry.

While the risk to the general public is low, the CDC says bird flu poses a greater threat to people with close or prolonged contact with infected cows, birds or other animals. Those people are encouraged to wear protective equipment and take other precautions.

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