What to know about the risks of the bird flu outbreak

An outbreak of bird flu is affecting dairy cows in the U.S.

Charlie Neibergall / Charlie Neibergall

The recent spread of avian influenza in dairy cattle in the U.S. has startled even some scientists who’ve tracked a global outbreak of the virus over the last few years.

“There’s a heap of unknowns right now,” says Richard Webby, a virologist at St Jude Children’s Research Hospital.

How widespread is the virus in dairy cattle? What could this mean for humans? None of this is clear yet.