A second type of bird flu has been found in U.S. dairy cows for the first time, the U.S. Department of Agriculture announced.

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.