A bird flu strain that is deadly to poultry has been confirmed at a fourth turkey farm in Minnesota, animal health officials said. The Board of Animal Health said that the highly pathogenic H5N2 virus was found at a commercial turkey farm in Nobles County. The farm has roughly 21,000 birds. The board said that the farmer noticed birds dying in one of three barns and reported it. The rest of the flock was killed as a precaution. According to officials, the risk to the public is very low and there is no food safety concern. The same virus has been found at three other Minnesota turkey farms in the last few weeks.