The Centers for Disease Control and Prevention (CDC) has identified mutations in the H5N1 bird flu virus that may increase its ability to infect humans. These mutations, found in the hemagglutinin (HA) gene,

Federal health officials have confirmed unsettling new details about the first United States case of severe bird flu,

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.