Three veterinarians who work with cows have tested positive for prior infections of H5 bird flu, according to a study released today by the Centers for Disease Control and Prevention.

Until last week, all bird flu in dairy herds had been identified as the B3.13 variant, which was believed to have come from wild birds in late 2023 or early 2024. The USDA confirmed the virus's existence in the Nevada dairy cattle through milk sampling, the agency said.