The bird flu virus in a patient in Louisiana has likely mutated while they were in the hospital. The Centers for Disease Control and Prevention said the mutations mean the H5N1 virus could potentially become more transmissible to humans.

A genetic analysis suggests the bird flu virus mutated inside a Louisiana patient who contracted the first severe case of the illness in the United States. The U.S.

The United States has confirmed its first known severe human infection of H5N1 bird flu, in a person in Louisiana believed to have contracted the virus through contact with sick or dead birds in a backyard flock.