Bird Flu 2025 Outbreak. It was also likely the first human infection with avian influenza a(h5n1) virus from a cow globally. The cases stem from a global outbreak of h5n1, a particular strain of bird flu that took off in 2020 and has hit poultry and dairy farms in the u.s.

Dairy cows with several recent human cases in u.s. 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.