A new variant of the bird flu has infected a dairy worker in Nevada marking the state's first human case of the H5N1 avian influenza.

A newer variant of H5N1 bird flu that recently infected dairy cattle in Nevada has a genetic change thought to help the virus infect mammals – including humans – more easily, according to a new brief from the USDA’s Animal and Plant Health Inspection Service.

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.