H5N1 bird flu, also known as avian influenza, continues to spread, with reports of a third human case from an unknown exposure source. To date, 67 cases have been confirmed, and one death has been reported in the U.

A new variant of the bird flu has infected a dairy worker in Nevada marking the state's first human case of the H5N1 avian influenza.

Cows in Nevada have been infected with a strain of H5N1 bird flu different from the strain detected in all other herds to this point in the ongoing dairy outbreak. It's the same strain that killed a Louisiana resident in early January and sent a Canadian teenager to intensive care in early November.