Virulent H5 avian influenza strains have spread to 14 states in five months and affected about 24 million birds so far, mostly egg-laying hens and turkeys, according to USDA. In Minnesota, the largest producer of U.S. turkeys, state officials said almost 5.5 million turkeys and egg-laying chickens have either died from the flu virus or are set to be killed in an effort to contain the outbreak.