Bird flu has been detected in Arizona dairy cattle milk, and a dairy farm has been placed under quarantine as a precaution, according to officials.

Dairy herds in Nevada have been infected by a version of the H5N1 bird flu not previously seen in cows, putting virologists on high alert.

A dairy worker in Nevada has been confirmed to be infected by a new bird flu strain found to be spreading among cows in the state last week . That strain of the H5N1 bird flu virus, called D1.1 by scientists, is different from a previous variant called B3.13 which had infected at least 40 dairy workers in the U.S. to date.