Bird Flu Virus Mutations Discovered in First Severe Human Case in US, CDC Says

The mutations may result in increased virus binding to cell receptors in the upper respiratory tract of humans, according to the health agency.

A person holds a test tube labeled "Bird Flu" in a photo illustration, on Jan. 14, 2023. Dado Ruvic/Reuters

The U.S. Centers for Disease Control and Prevention has found mutations in samples taken from a man infected with the first severe case of avian influenza in the United States, mutations that were not present in specimens collected from his infected backyard flock.

The agency began analyzing the samples after the patient—a resident of southwestern Louisiana, aged over 65—was confirmed last week as the first person in the United States with a severe case of H5N1 bird flu.