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For more information contact a WDFW Regional Office


If you find a dead bat or notice bats exhibiting unusual behavior such as flying outside during the day or freezing weather, please leave a message on our Wildlife Health Hotline (800) 606-8768.

Photo of bats hanging from cave wall exhibiting Geomyces destructans fungus on their muzzles. This is the fungus associated with WNS.
Click on photo to enlarge
Bats exhibiting Pseudogymnoascus destructans fungus on their muzzles. This fungus causes WNS in bats.
Nancy Heaslip, New York Department of Environmental Conservation
Range map for White Nose Syndrom as of March 2016
Click on map for latest range info

White-Nose Syndrome of Bats Fact Sheet

March 2016

What is it?

White-nose syndrome (WNS) of bats is a disease caused by the fungus Pseudogymnoascus destructans (formerly known as Geomyces destructans). The disease is estimated to have killed over six million bats in the eastern United States since 2006, and can kill up to 100% of bats in a colony during hibernation. There has been one confirmed case of White-nose syndrome in Washington to date in a little brown bat found near North Bend (30 miles east of Seattle) in March 2016.

The fungus grows on noses, wings and ears of bats during winter hibernation, giving them a white, fuzzy appearance. The fungus invades deep skin tissues and causes extensive damage.  Affected bats arouse more often during hibernation which causes them to burn up their crucial fat reserves needed to sustain them through hibernation, leading to starvation and death. Additional causes for mortalities may include impairment of physiological processes due to wing damage, including reduced circulatory and thermoregulatory abilities, reduced gas exchange capabilities, and dehydration.

The fungal disease is thought to be spread primarily from bat to bat contact.  However, people can carry fungal spores on their clothing, shoes, or caving gear.  Appropriate decontamination is critical to reduce the risk of spreading this potentially catastrophic bat disease.

Species Affected

To date, seven cave hibernating species of bats in North America are afflicted by the disease. These include:

  • Little brown bat (Myotis lucifugus)
  • Northern long-eared bat (M. septentrionalis)
  • Eastern small-footed bat (M. leibii)
  • Indiana bat (M. sodalis; federally endangered)
  • Gray bat (M. grisescens; federally endangered)
  • Tricolored bat (Perimyotis subflavus)
  • Big brown bat (Eptesicus fuscus)

Little brown bats and big brown bats occur in Washington, in addition to another 11 species that are potentially at risk in this state. There is currently no indication that humans or other animal species are susceptible to infection with the fungus that causes White-nose syndrome.

Clinical signs in bats

Clinical signs of White-nose syndrome in bats include:

  • presence of a white powder-appearing substance on their nose, wings or ears during hibernation when body temperature is reduced and the environment is near freezing;
  • emaciation;
  • damaged wings with potential loss of flight; and
  • activity during winter, including flying outside during freezing temperatures.

    Photo of  a normal wing of little brown bat. Photo of a little brown bat with skin infection on wing.
    Normal wing of little brown bat.
    Photo: Greg Falxa, WDFW

    Little brown bat with
    skin infection on wing.
    Photo: Progressive Animal Welfare Society (PAWS)


White-nose syndrome appears to spread primarily through physical bat-to-bat contact or infected environment-to-bat contact. Humans have the potential to spread the fungus to new locations when it may attach to clothing and gear used in caves, mines and roosts. Fungal spores are incredibly resilient and can survive in the environment for long periods of time. People who visit bat roosts, caves, and mines are strongly urged to decontaminate all clothing and gear immediately afterwards by using appropriate cleaning and disinfection protocols (see U.S. Fish and Wildlife Service Decontamination Protocol)


  • Contact the Washington Department of Fish and Wildlife or the U.S. Fish and Wildlife Service immediately if you suspect you have seen bats with this condition, or if you see bats flying outside during freezing temperatures.
  • Do not handle live bats. Please refer to the online reporting form for information if you have found a sick or dead bat.
  • Avoid entering caves, mines or other areas used by bats for unnecessary reasons to avoid disturbing bats and potentially spreading the disease to unaffected areas.
  • People who must enter caves, mines or bat roosts should decontaminate all equipment and clothing immediately after visiting. Do not allow dogs in caves (they may act as carriers of the fungus to new sites).
Picture of researcher with dead bats infected with WNS
Greg Turner with many dead bats during winter.
PA Game Commission


Bats are valuable members of ecosystems around the world, saving farmers in the U.S. alone over $3 billion annually in pest control services. One colony of bats can consume many tons of insects that would otherwise consume valuable crops and forests, or otherwise threaten human health and well-being. Many species of bats are also valuable for the pollination of plants and dispersal of plant seeds.

Over six million bats are estimated to have died due to this disease over the past few years in the eastern US and Canada, with as much as 100% mortality in some colonies. This disease could possibly lead to the extinction of some bat species.

Key Findings

  • White-nose syndrome causes very high mortality (up to 100%) in bat colonies during hibernation.
  • The pathogen responsiblefor the disease is Pseudogymnoascus destructans (formerly Geomyces destructans).
  • Bat-to-bat and infected environment-to-bat contact appear to be the primary transmission routes, although humans can likely transfer the fungus to new locations and thereby assist in spreading the disease.
  • The fungus and disease are spreading across North America towards the West and into Canada.
  • Many species of bats are potentially susceptible; currently seven species are known to be affected.