Five people who work at a poultry farm in northeastern Colorado have tested positive for the bird flu, the Colorado public health department reported July 14. This brings the known number of U.S. cases to nine. The five people were likely infected by chickens, which they had been tasked with killing in response to a bird flu outbreak at the farm. More than 99 million chickens and turkeys have been infected with a highly pathogenic strain of the bird flu that emerged at U.S. poultry farms in early 2022. Since then, the federal government has compensated poultry farmers more than $1 billion for …