Bird flu virus likely mutated within Louisiana patient who became severely ill, CDC says PBS NewsHourGenetic Sequences of Highly Pathogenic Avian Influenza A(H5N1) Viruses Identified in a Person in Louisiana CDCBird Flu Samples From Very Ill Patient Had ‘Concerning’ Mutations The New York TimesCDC: H5N1 mutations in severely ill patient could boost spread, but risk remains low University of Minnesota Twin CitiesBird flu virus shows mutations in first severe human case in US, CDC says Reuters