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,

The report is the latest evidence that the outbreak in dairy herds is spreading undetected in cows, and the spillover into people at highest risk of exposure is going unnoticed.

For the first time since 1952, publication of the CDC's Morbidity and Mortality Weekly Report was halted. It returned on Feb. 6, but without planned bird flu studies.