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 . The patchy surveillance means infections in people may go undetected, making it . 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..
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