A little brown bat found in a New York cave exhibits fungal growth on its muzzle, ears and wings. Photo: Al Hicks via USGS

Scientists may have discovered a solution to combat the fungus that causes white-nose syndrome in bats.

White-nose syndrome has been wiping out populations of bat species throughout North American since 2006. It first emerged in New York state, but has since been reported as far south as Florida and Texas, and out west in Washington. The disease can result in up to 90 percent mortality in some populations.

The fungus, Pseudogymnoascus destructans (P. destructans), grows on the wings, snout and ears of hibernating bats. The fungus disrupts bats as they hibernate, causing them to wake up and burn the limited fat stores they need to survive winter.

P. destructans is known to thrive only in cold, dark environments (such as caves) with a strict temperature range of 39 to 68 F, so it can only affect bats during hibernation.

P. destructans evolved alongside bat species in Europe and Asia for millions of years, allowing Eurasian bats to develop defenses against it while leaving their counterparts in North America vulnerable.

Effective prevention methods or cures for the lethal syndrome have not been successful, but a recent breakthrough is providing some optimism among researchers.

A team from the U.S. Forest Service, U.S. Department of Agriculture and the University of New Hampshire conducted a genomic analysis on P. destructans and identified a potential “Achilles heel” – the fungus is highly sensitive to UV light.

The researchers compared P. destructans’ genome to six of its non-pathogenic relatives to better understand the factors that make P. destructans so deadly, and discovered that the fungus lacks a key DNA repair enzyme. The team then exposed all the fungi to varying intensities of UV light and observed how each fungi reacted.

A low dose exposure of the UV light resulted in a 15 percent survival rate of P. destructans, and a moderate dose led to just a one percent survival. These values translate to a few seconds of exposure from a hand-held UV-C light source, according to the study authors.

“It is unusual that P. destructans appears to be unable to repair damage caused by UV light,” said Jon Palmer, a research botanist in the Northern Research Station’s lab in Madison, Wis., and the lead author of the study. “Most organisms that have been found in the absence of light maintain the ability to repair DNA caused by UV light radiation. We are very hopeful that the fungus’ extreme vulnerability to UV light can be exploited to manage the disease and save bats.”

Now that researchers have a tool to fight the fungus, the next step is determining how to best use it. Treating hibernating bats with UV light multiple times throughout the winter would be difficult on a large-scale, and could disrupt the animals’ hibernations anyway. Follow-up research led by corresponding author Daniel Lindner, funded by a grant from the National Fish and Wildlife Foundation, is already underway.

“This research has tremendous implications for bats and people,” said Tony Ferguson, director of the Forest Service’s Northern Research Station and the Forest Products Laboratory. “Bats play a key role in the health of forests as well as the production of food in the United States, and developing an array of tools with which we can treat bats for white-nose syndrome is important to preserving these very important species.”

The study was published Jan. 2 in Nature Communications.