White Nosed Bat Syndrome in Washington State

White-Nose Syndrome

May 2016

What is it?

White-nose syndrome is a disease caused by the fungus Pseudogymnoascus destructans. The disease is estimated to have killed over six million bats in eastern North America since 2006, and can kill up to 100% of bats in a colony during hibernation.

In March 2016, Washington’s first case of white-nose syndrome was confirmed in a Little Brown Bat (Myotis lucifugus) near North Bend, 30 miles east of Seattle. Though the disease has devastated bat populations in eastern North America, we do not yet know how it will impact western bats.  In general, bats in Washington do not hibernate in large aggregations like bats do in eastern North America.  Thus, the spread of the disease in western North America may be different.

The fungus can grow on the nose, wings and ears of an infected bat during winter hibernation, giving it a white, fuzzy appearance. Once the bats wake from hibernation, this fuzzy white appearance goes away. Even though the fungus may not be visible, it invades deep skin tissues and causes extensive damage.  Affected bats arouse more often during hibernation which causes them to use crucial fat reserves, leading to possible starvation and death. Additional causes of mortality from the disease include wing damage, inability to regulate body temperature, breathing disruptions, and dehydration.

The fungal disease is spread primarily from bat-to-bat contact. Bats can also contract the disease from an environment where the fungus is present. People can carry fungal spores on clothing, shoes, or recreation equipment that has come in contact with the fungus.  Appropriate decontamination for clothes and equipment used in areas where bats may live is critical to reduce the risk of spreading this catastrophic bat disease.

Species affected in Washington

To date, it is unknown which of Washington’s 15 bat species will be affected by the fungal disease.  A single documented case in a Little Brown Bat indicates that this species is vulnerable to the fungus.  We need to gain more information not only on the disease in Washington, but also on our bat populations.  

In eastern North America, seven cave hibernating species are afflicted by white-nose syndrome. Two of these species are found in Washington: the Little Brown Bat (Myotis lucifugus) and Big Brown Bat (Eptesicus fuscus).

White-nose syndrome is not known to pose a threat to humans, pets, or other animal species.

Clinical signs of white-nose syndrome

Clinical signs of White-nose syndrome in bats include:

  • Dehydrated, wrinkled or damaged skin on wings
  • Loss of flight
  • Emaciation

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