Bird Flu Cases In Usa 2025. By february, more than 50 million chickens have been affected in the u.s., in what has become one of the largest bird flu. The first human case of h5n1 bird flu linked to an outbreak in dairy cows in the united states was reported on april 1, 2025, in texas.

It was also likely the first human infection. A third person in the us has tested positive for h5 bird flu in connection to an ongoing outbreak in dairy cattle, the michigan department of health and human services said.