Bird flu could merge with seasonal flu to make mutated virus that could spread among humans, CDC warns FortuneAs pace and severity of human H5N1 cases accelerate, NIH leaders call for more action on bird flu CNNCalifornia probe ties cat's avian flu illness to raw pet food University of Minnesota Twin Cities‘Concerning’ Bird Flu Mutation Found In Human The Weather ChannelHow America lost control of the bird flu and raised the risk of another pandemic PBS NewsHour