White-nose syndrome (WNS) is a fatal disease in bats caused by the fungus Pseudogymnoascus destructans. The disease affects cave-dwelling bats. Researchers first discovered the disease in New York in the winter of 2006. Since then, it has spread to more than half of the United States, killing millions of bats--up to 99% of some bat colonies. The National Park Service works with many other state and federal agencies as well as conservation organizations to learn more about the fatal disease and how to slow its spread.
The articles below explain more about white-nose syndrome, or you can watch the video Battle for Bats: Surviving White-nose Syndrome. It's available in Spanish, too: La Batalla por los Murcielagos: Sobrevivir al Sindrome de la Nariz Blanca.