Here's what worries scientists about bird flu's spread among cattle

With diary cows getting bird flu, researchers are trying to figure out what mutations could make the virus a threat to humans.

Charlie Neibergall / Charlie Neibergall

The outbreak of bird flu in dairy cattle is still unfolding.

On Wednesday, North Carolina became the seventh state to detect the virus in a dairy herd.

The unlikely spread among cattle and one dairy worker has scientists looking through the data to better understand this spillover. They say the risk to humans hinges on whether the virus can evolve in key ways to better infect mammals.