What is the risk of bird flu spillover in humans? The Boston GlobeBird flu has spread to cows in Colorado. Is avian influenza threat? We answer your questions. The Denver PostOpinion | If H5N1 spreads among farmworkers, it could lead to a pandemic The Washington PostUSDA reports more H5N1 detections in poultry, wild birds University of Minnesota Twin CitiesUS Bird Flu Risk: 1 Human Case Reported, More Likely to Follow Bloomberg