The current human case count of H5N1 influenza in the US could be an underestimate, according to a new study from the Centers for Disease Control and Prevention (CDC). After testing 150 veterinarians,

Three U.S. dairy veterinarians unknowingly had H5N1 infections, otherwise known as bird flu. This included one person who worked only in states without known outbreaks in cows, according to a new study from the U.

Three veterinarians had antibodies to bird flu virus, which suggests recent infection, the report said. None of them knew they were working with dairy cattle with known or suspect