A century ago, Americans so vehemently hated the wolves of their Western states that they attacked them with germ warfare.

Veterinarians deliberately infected coyotes with a disease called mange, hoping it would spread to the wolves, which it did, causing many of them to lose so much fur that they froze to death in the harsh winters.

Now, according to a recent study by Penn State University researchers, mange survived in other animals long after the wolves were gone.