Blood testing of large-animal veterinarians suggests that H5N1 bird flu has spread more widely than US surveillance of the virus is capturing, according to a new study by federal and state disease detectives.

A new report suggests that more Americans may be walking around with bird flu − and not even know it. Researchers from the Centers for Disease Control and Prevention randomly tested 150 veterinarians for H5N1,

A new study shows the bird flu has silently spread from animals to some veterinarians. It echoes two smaller studies that detected evidence of infection in previously undiagnosed farmworkers.