Growing concerns surrounding the transmission of H5N1 bird flu. The CDC reports that samples collected from a severely ill patient in Louisiana showed signs of mutation, as they differ from the samples collected from sick and dead birds believed to have infected the man in the first place.

The genetic analysis of the H5N1 avian flu virus in specimens from the nation's first severely ill hospitalized patient in Louisiana reveals mutations that may enable upper-airway infection and greater transmission, concludes a technical summary from the Centers for Disease Control and Prevention (CDC).