After a new study showed that bird flu has spread to dairy farm workers more often than previously known, the US Centers for Disease Control and Prevention is expanding its recommendations for testing and treatment of workers on farms where animals have tested positive.

New guidance comes after a study showed that some dairy workers had signs of infection, even when they didn't report feeling sick

Federal health officials are recommending expanded testing of dairy farm workers after a new study found evidence of previously undetected cases of bird flu in humans. Why it matters: The study is leading officials to recommend the testing of all workers at farms where the H5N1 virus is detected,