In a positive finding, the CDC emphasized that there is no evidence the virus has spread from the Louisiana patient to others, and the mutations alone are unlikely to spread from person to person. CDC scientists also confirmed, however, that the Louisiana virus samples are closely related to candidate vaccine strains already developed for bird flu.

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.

A genetic analysis of the bird flu in the body of a Louisiana man who contracted the first severe case found it mutated inside of his body, a development that could allow the virus to more easily spread 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 CDC said that testing of a person with a severe case of bird flu indicated the virus had mutated but the risk remains low to the public as no human-to-human transmission has been documented.