Bats Threatened by White Nose Syndrome

The Swamp Stomp


Volume 19, Issue 1

A fungal disease that has been called “the deadliest disease to hit wildlife in the United States in recorded history” is threatening fifteen species of bats living in North America.(1) The disease is called White Nose Syndrome (WNS), and bats are the only animals that appear to be affected by this pathogen. Six of these 15 affected bat species are now either threatened or endangered with the possibility of becoming extinct altogether.

The actual scientific name for White Nose Syndrome is Pseudogymnoascus destructans, or Pd for short. Pd can infect up to 90% of a bat hibernaculum, which is a place such as a cave, where the bats hibernate over the winter months.  Bats normally hibernate in colonies of hundreds of bats so the infection spreads quickly through a colony and with devastating results. Whole colonies of bats can succumb to the disease in a single winter.  Already, the fungus has killed almost six million bats in North America. 

Pd attacks the bare skin of the bat (primarily the wings and faces) and produces a white fuzz on the surface. Because of this attack to their skin, the bats will periodically and unnaturally awaken while hibernating.  During a normal hibernation period, bats do awaken from time to time and use some small portion of their stored fat. However, the unnatural activity of the disease causes the bat to use much more of the stored fat that is required to survive the hibernating period.  Bats literally die of starvation from the fungus.(1)

The fungus finds its way into the caves of bat hibernacula through many different avenues. Infected bats can leave the fungus behind on the surface of a cave as they travel from cave to cave.  Sometimes cavers, people who study or investigate caves, carry it on their clothing from one bat hibernaculum to the next, and then there are winds and other external sources that may also be factors that introduce the fungus to a cave. Once introduced to a new setting, the fungus attaches itself to the substrate of the cave walls waiting for an unsuspecting bat.

Pd was first discovered in North America in an area near Albany, New York in the year 2006.  No one knows how it reached our continent, but research into the fungus has traced its initial existence to Eurasia many years prior to 2006.  In Eurasia however, the fungus has been around long enough that the bats there have built an immunity to it.  After its initial discovery in our country in 2006, the pathogen has spread across the US into the Midwest and into some portions of Canada.

There is ongoing research into a “cure” for WNS.  Research into the genome of the fungus and others like it, has shown that Pd is missing an enzyme that turns off reparation of DNA after exposure to UV light. This is one avenue that is being pursued by researchers to help eradicate the fungus from hibernacula before the bats have a chance to settle into their cave for the winter months.

Researchers are also studying the habits of some of the hibernating bats that survive WNS.  They have found that Big Brown Bats have developed a strategy of a unified awakening of the whole colony on a nightly basis in response to the WNS and researchers hypothesize that the heat from surrounding bats helps store energy and hence, fat, making survival of the season an option.(1)

The latest research shows that there are bats that have been infected, survived, and then become pregnant. Their immunity will be passed on to their offspring and there will be more and more immunity as these bats survive into the next generation. Natural selection is working for this species of bats, but what about the others? The disease is still new and spreading in North America. It may take many more years before either the fungal pathogen is eradicated or controlled, or multiple native bat species are able to combat the disease through immunity.  Let’s hope that the bats can hold out until this pathogen is no longer a problem.

1. ”White Nose Syndrome. The mystery fungus killing our bats.” Wild Things Sanctuary.org. nd. <www.wildthingssanctuary.org/bats–white-nose-syndtomr.html>

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