Deadly Bat Fungus Found at Mount Rainier National Park


A report released by the Washington Department of Fish and Wildlife this month reveals that a fungus that causes fatal white-nose syndrome in bats has been detected in Lewis County. 

That finding means the fungus is now known to exist on bats in two Washington counties, following numerous reports from King County dating back to March 2016.

Since that first discovery two years ago, the WDFW has teamed with the National Park Service to collect samples from live bats in an attempt to understand the spread of the fungus and its associated disease. 

In March 2017, researchers swabbed the wings of 24 bats roosting in the Lewis County section of Mount Rainier National Park. Those tests revealed that four of the bats were infected with the fungus that causes white-nose syndrome, or Pseudogymnoascus destructans. The fungus was found on two little brown bats and two Yuma myotis, although no bats in the colony showed signs of having developed white-nose syndrome.

White-nose syndrome is estimated to have killed millions of bats in eastern North America since 2006. It can wipe out an entire colony during one hibernation period. Scientists are not yet certain if the fungus and disease will have the same severe impact in Washington since western bats do not hibernate in large groups as eastern bats do. 

The fungus typically takes hold on the nose, wings and ears of an infected bat during winter hibernation, resulting in a white, fuzzy appearance. Even when the fungus is not visible to the naked eye, it can still root into deep skin tissues and cause severe damage. The spread of the fungus also causes infected bats to awaken more frequently during hibernation, which results in the burning of critical fat reserves that can result in starvation and death. Mortality can also be caused by wing damage, inability to regulate body temperature, breathing disruptions, and dehydration.

A press release from the WDFW noted that the bats use the Lewis County roosting area in the spring and summer, but it is unknown where they hide away in the winter months. Scientists have explained that detection of fungal spores in the Lewis County roosting area is of particular importance because it is the first confirmed detection of the fungus in Washington outside the boundaries of King County. Scientists fear the presence of the fungus is more widespread than first thought and that it might be spreading.

While many people harbor unfounded fears of bats, scientists note that they are valuable participants in the ecosystem and even benefit farmers financially through their pollinating and pest-eating services. It is estimated that bats save U.S. farmers more than $3 billion each year in pest control. 

One colony is believed to be able to consume several tons of insects during one growing season alone. In addition to eating bugs that threaten cash crops or human health, they also consume moths and beetles known to be harmful to trees and forests.

The fungus that causes white-nose syndrome is not known to be harmful to humans, livestock, or pets. 

It can survive for years in underground environments such as caves and mines. Scientists are currently trying to figure out how long it can persist in other environments that bats frequent, such as cliffs, attics and bridges. It is believed that winter hibernating areas may serve as reservoirs for the fungus and that bats who use, or even visit, infected hibernation spots run the risk of catching or transferring the fungus.

While scientists believe that the fungus is spread primarily from bat-to-bat contact, they warn that humans can also carry fungal spores on clothing, shoes and recreation equipment. In a press release, the WDFW noted that, “Properly decontaminating shoes, clothes and equipment used in areas where bats live is critical to reduce the risk of spreading white-nose syndrome.”

The WDFW cautions that humans should never handle live bats and anyone who is exposed to a bite, scratch or saliva from a dead or live bat should call their local public health department immediately. Additional information on decontaminating outdoors equipment and clothing can be found online at

The WDFW also noted that citizens can help by reporting observations of groups of bats online at


March 2016

A live little brown bat infested with white-nose syndrome was found on a trail in Olallie State Park by a hiker. A silver-haired bat was also found in a Seattle park that was found to have the disease causing fungus.


June 2016/17

Guano collected under a day-roosting spot beneath a bridge near North Bend in King County tested positive for white-nose syndrome-inducing fungus two summers in a row.


April 2017

Two dead bats infected with white-nose syndrome were found in separate locations near North Bend.


May 2017

Guano collected from a maternity roost near North Bend tested positive for the fungus, and researchers collected samples from live bats at Mount Rainier National Park in Lewis County. In February 2018, lab results showed four bats tested positive for the fungus.


January 2018

A live bat was found floating alive in Lake Union near Seattle. It died on the way to a rescue facility and tested positive for white-nose syndrome. Additionally, a bat infected with white-nose syndrome was found in North Bend at the same location as the April report.