As bird flu spreads in cows, here are 4 big questions scientists are trying to answer

Bird flu is spreading through U.S. dairy cattle. Scientists say the risk to people is minimal, but open questions remain, including how widespread the outbreak is and how the virus is spreading. (DOUGLAS MAGNO/AFP via Getty Images)
On Friday, Colorado became the latest state to detect the bird flu virus spreading in dairy cattle. It follows revelations earlier in the week that viral fragments are turning up in retail milk.
Still, scientists don’t view this as an immediate threat to human h