The person has been hospitalized, state health officials say; the investigation indicates they came in contact with sick or dead birds that were infected with the virus.

As of December 30, the CDC has confirmed 66 human cases of the bird flu virus in the United States. Most of them were mild infections among dairy workers and others who had contact with infected animals.

Federal health officials say that not only has a Louisiana resident contracted the first severe case of bird flu in the U.S., but that the virus likely mutated in the patient. The findings raise concern regarding the adaptability of the virus.

Federal health officials have confirmed unsettling new details about the first United States case of severe bird flu, reported recently in a hospitalized patient in Louisiana. Genetic samples from the patient contained mutations that could,