White-nose Syndrome

White-nose syndrome is the result of a fungus called Geomyces destructans, which invades and ingests the skin of hibernating bats, including the wings. It causes bats to wake up more frequently during the winter, possibly because of water loss from damaged tissue. Bats aroused from hibernation burn up large amounts of limited winter fat reserves and often starve to death because of a lack of insects during the cold months. In some cases, their wings are too damaged to fly. Dead or dying bats are frequently observed with a white fuzz around their muzzles, hence the name “white-nose syndrome.”

Typically, the disease kills 70 percent to 90 percent of bats in affected hibernacula (the areas where bats gather to hibernate for the winter). In some cases, the mortality rate has been 100 percent, wiping out entire colonies. Some caves that once hosted hundreds of thousands of bats are now empty.

It’s estimated that to date white-nose syndrome has killed about 6.7 million bats in North America.

Although its exact origins are unclear, there’s strong evidence that white-nose syndrome was originally transported from Europe, where the fungus exists but does not kill bats. The syndrome was first discovered in North America in a cave frequently visited by people in upstate New York in February 2006. Because bats do not travel between Europe and North America, this provides compelling evidence that the fungus was introduced to the Northeast by cavers travelling between continents.

The fungus is passed from one bat to another, but it also likely spreads when people inadvertently carry it from one cave to another on their shoes, clothes or equipment.

White-nose syndrome appears only to affect bats that hibernate, which make up about half of the 45 bat species in the United States. Pollinating bats and long-distance migratory bats that don’t hibernate don’t seem to be affected.

So far, 11 species (including four endangered species) have been affected by the disease or are immediately threatened by it. The disease has affected the big brown bat, the Eastern small-footed bat, the Indiana bat (endangered), the little brown bat, the northern long-eared bat and the tricolored bat. The fungus has also been found on the cave bat, the gray bat (endangered) and the southeastern bat. Other endangered bats living in areas where the fungus is present are the Virginia big-eared bat and the Ozark big-eared bat.

The disease has been confirmed in 19 states and four Canadian provinces: in the United States, Alabama, Connecticut, Delaware, Indiana, Kentucky, Maine, Maryland, Massachusetts, Missouri, New Hampshire, New Jersey, New York, North Carolina, Ohio, Pennsylvania, Tennessee, Vermont, Virginia and West Virginia; in Canada, New Brunswick, Nova Scotia, Ontario and Quebec. The fungus has also been found on bats in Oklahoma. See an animation of the disease’s spread since 2006.