A virologist explains that why this probably isn’t the big one — but that it’s a sign of bad things happening with the virus.

The patient in Louisiana who was hospitalized with severe bird flu illness was found to have a mutated version of the virus. Doctors react and share their concerns.

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.