Bats hit by killer white-nose syndrome

A mysterious disease has been sweeping across the United States, killing more than a million bats.

Called white-nose syndrome, it has left some bat species on the brink of extinction, and scientists are struggling to find a way to stop its spread.

Here, Carl Herzog, a wildlife biologist with the New York State Department of Environmental Conservation, makes a rare visit to an abandoned mine to assess the devastation that this deadly disease has left in its wake.