A strain of bird flu has been circulating in dairy cows for almost five months
Lauren Justice/Bloomberg via Getty Images
US health officials are struggling to monitor people who have been exposed to a bird flu virus circulating in dairy cows. The patchy surveillance means infections in people may go undetected, making it difficult to mitigate the virus’s spread. This raises the risk of the pathogen developing mutations that could make it more dangerous to people.
The virus, a strain of avian influenza known as H5N1, has killed millions of birds and thousands of mammals worldwide. It…