National Wildlife Health Center

...advancing wildlife and ecosystem health

White-Nose Syndrome (WNS)


White-nose syndrome (WNS) is an emergent disease of hibernating bats that has spread from the northeastern to the central United States at an alarming rate. Since the winter of 2007-2008, millions of insect-eating bats in 25 states and five Canadian provinces have died from this devastating disease. (see map below) The disease is named for the white fungus, Pseudogymnoascus destructans, that infects skin of the muzzle, ears, and wings of hibernating bats. In April 2014, WNS was confirmed in Michigan and Wisconsin.

The USGS National Wildlife Health Center (NWHC), along with the U.S. Fish and Wildlife Service and other partners continue to play a primary role in WNS research. Studies conducted at NWHC led to the discovery, characterization, and naming of the causative agent (the cold-loving fungus P. destructans), and to the development of standardized criteria for diagnosing the disease. Additionally, scientists at the NWHC have pioneered laboratory techniques for studying impacts of the fungus on hibernating bats.

To determine if bats are affected by white-nose syndrome, scientists look for a characteristic microscopic pattern of skin erosion caused by P. destructans. Field signs of WNS can include visible white fungal growth on the bat’s muzzle and/or wing tissue, but this is not a reliable indicator. Infected bats also often display abnormal behaviors in their hibernation sites (hibernacula), such as movement toward the mouth of caves and daytime flights during winter. These abnormal behaviors may contribute to the untimely consumption of stored fat reserves causing emaciation, a characteristic documented in a portion of the bats that die from WNS.

Current estimates of bat population declines in the northeastern US since the emergence of WNS are approximately 80%. This sudden and widespread mortality associated with WNS is unprecedented in hibernating bats, among which disease outbreaks have not been previously documented. It is unlikely that species of bats affected by WNS will recover quickly because most are long-lived and have only a single pup per year. Consequently, even in the absence of disease, bat populations do not fluctuate widely in numbers over time.

The true ecological consequences of large-scale population reductions currently under way among hibernating bats are not yet known. However, farmers might feel the impact. In temperate regions, bats are primary consumers of insects, and a recent economic analysis indicated that insect suppression services (ecosystem services) provided by bats to U.S. agriculture is valued between 4 to 50 billion dollars per year.

Despite efforts to contain it, WNS continues to spread. Within the last two years, the disease has been confirmed in several central states, including Alabama, Indiana, Kentucky, Tennessee, and Missouri. High mortality of bats has not yet been reported at these locations, and it remains to be seen if WNS will develop and manifest in warmer parts of the US or other temperate regions of the world with severity similar to that in the northeastern US. See the map below for WNS occurrences in North America.

WNS Occurrence by County

WNS by county
Map courtesy of Cal Butchkoski, Pennsylvania Game Commission.

Report WNS observations to your state conservation agency, the U.S. Fish and Wildlife Service or the USGS National Wildlife Health Center.

To report wildlife mortality events to USGS, please visit the mortality reporting page or contact a member of NWHC’s Field Investigations Team:

WNS Related Links

WNS Photo Gallery

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Battle For Bats: Surviving White Nose Syndrome

Battle For Bats: Surviving White Nose Syndrome was produced for the USDA Forest Service by Ravenswood Media. It shows how government and private agencies have come together to search for solutions to help our bat populations overcome WNS. The public can also play a role in the future of bats by providing habitat and surveying their populations. Bats are a critical component in a healthy forest ecosystem, plus they provide significant agricultural pest control and pollination. Their survival is essential for a sustainable natural environment.

Watch Video

Experimental infection of bats with Pseudogymnoascus destructans causes white-nose syndrome

Researchers have confirmed that a recently identified fungus is responsible for white-nose syndrome, a deadly disease that is sweeping through bat colonies in eastern North America. Full Article

Bat White-Nose Syndrome: An Emerging Fungal Pathogen?

A previously undescribed, cold-loving fungus has been linked to white-nose syndrome, a condition associated with the deaths of over one million hibernating bats in the northeastern United States. The findings are published in the January 9, 2009 issue of Science. Download PDF

Other WNS Publications
WNS Health Bulletins

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Page Last Modified: May 29, 2014