The U.S. Centers for Disease Control said on Thursday its analysis of samples from the first severe case of bird flu in the country last week showed mutations not seen in samples from an infected backyard flock on the patient's property.

A patient in Louisiana has been hospitalized with a severe case of H5N1 bird flu, the US Centers for Disease Control and Prevention said, the first such case in the United States.

Highly contagious H5N1 avian influenza, or “bird flu,” has been found in a Mississippi chicken flock. It’s the first major case of bird flu in Mississippi since 2023.