How does white-nose syndrome kill bats?

January 5, 2015, United States Geological Survey
Long-wave ultraviolet (UV) and white-light illumination of lesions associated with white-nose syndrome. Wing from dead eastern pipestrelle (Pipistrellus subflavus) lit from above with hand-held 51 LED 385-nm UV flashlight shows points of orange-yellow fluorescence. Credit: U.S. Geological Survey

For the first time, scientists have developed a detailed explanation of how white-nose syndrome (WNS) is killing millions of bats in North America, according to a new study by the U.S. Geological Survey and the University of Wisconsin. The scientists created a model for how the disease progresses from initial infection to death in bats during hibernation.

"This model is exciting for us, because we now have a framework for understanding how the functions within a bat," said University of Wisconsin and USGS National Wildlife Health Center scientist Michelle Verant, the lead author of the study. "The mechanisms detailed in this model will be critical for properly timed and effective disease mitigation strategies."

Scientists hypothesized that WNS, caused by the fungus Pseudogymnoascus destructans, makes die by increasing the amount of energy they use during winter . Bats must carefully ration their energy supply during this time to survive without eating until spring. If they use up their limited energy reserves too quickly, they can die.

The USGS tested the energy depletion hypothesis by measuring the amounts of energy used by infected and healthy bats hibernating under similar conditions. They found that bats with WNS used twice as much energy as healthy bats during hibernation and had potentially life-threatening physiologic imbalances that could inhibit normal body functions.

Scientists also found that these effects started before there was severe damage to the wings of the bats and before the disease caused increased activity levels in the hibernating bats.

USGS pathologist Nancy Thomas and technician Dottie Johnson necropsy little brown bat at the USGS National Wildlife Health Center. Credit: Allison Klein, NPS
"Clinical signs are not the start of the disease—they likely reflect more advanced disease stages," Verant said. "This finding is important because much of our attention previously was directed toward what we now know to be bats in later stages of the disease, when we observe visible fungal infections and behavioral changes."

Key findings of the study include:

  • Bats infected with P. destructans had higher proportions of lean tissue to fat mass at the end of the experiment compared to the non-infected bats. This finding means that bats with WNS used twice as much fat as healthy control bats over the same hibernation period. The amount of energy they used was also higher than what is expected for normal healthy hibernating little brown bats.
  • Bats with mild wing damage had elevated levels of dissolved carbon dioxide in their blood resulting in acidification and pH imbalances throughout their bodies. They also had high potassium levels, which can inhibit normal heart function.

Wing damage from white-nose syndrome fungus in a little brown bat. Credit: Kim Miller, U.S. Geological Survey

Explore further: Fungal disease fatal to bats spreads to half of US

More information: The study, "White-nose syndrome initiates a cascade of physiologic disturbances in the hibernating bat host," is published in BMC Physiology: www.biomedcentral.com/1472-6793/14/10

Related Stories

UA researchers trace bat killer's path

January 29, 2014

As North American bats face a death toll approaching 7 million, University of Akron scientists reveal new clues about their killer, White Nose Syndrome, or WNS. The UA researchers reveal that the deadly WNS fungus can likely ...

Hibernation keeps rabies going in bats

June 7, 2011

(PhysOrg.com) -- In a new study published in the Proceedings of the National Academy of Sciences, infectious disease biologist Dylan George from Colorado State University reports that a bat’s hibernation is what keeps ...

Recommended for you

Computing the origin of life

December 14, 2018

As a principal investigator in the NASA Ames Exobiology Branch, Andrew Pohorille is searching for the origin of life on Earth, yet you won't find him out in the field collecting samples or in a laboratory conducting experiments ...

0 comments

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.