Scientists diagnose white-nose syndrome in bats using ultraviolet light

If you’re looking for an animal to feel sorry for, you’ve got options. But of all the bad things going down in wildlife around the world, white-nose syndrome in North American bats is among the most devastating. Caused by a fungus with the appropriately super-villainish name of pseudogymnoascus destructans, this disease infects hibernating bats and, more often than not, kills them. Sometimes 90 to 100 percent of all the bats in a given cave (“hibernacula” to be technical) can die out from one year to the next. Millions of bats are already dead as a result, and the disease is spreading.

One of the key tools in managing white-nose syndrome is, of course, understanding where it is, and where it isn’t. But firm diagnoses have only been possible with histologic analysis; that means killing a live bat in order to figure out if it has the thing that might kill it. I think we can all agree that isn’t the greatest idea. A new paper, though, by experts from the U.S. Geological Survey, the Pennsylvania Game Commission, and elsewhere, describes a new, benign way to test for white-nose syndrome: ultraviolet light.

Telltale fluorescence under UV light of a bat infected with white-nose syndromeScientists showed a long time ago—1925!—that long-wave UV light illuminates certain fungal infections. So the researchers tested this idea out on 168 bats across 11 states, and compared the results to histologic testing. They found that the UV works extremely well: of 80 bats that showed telltale orange fluorescence under the UV light, 79 of them tested positive for white-nose. That means an agreement of 98.8% between the methods, and all the bats deemed negative by UV testing were also negative by histologic analysis.

“This nonlethal assessment technique can also assist natural resource managers and researchers investigating WNS by facilitating the ability to track progression of disease in individual bats and by providing the potential, in the hands of trained field personnel, to generate accurate preliminary on-site results to inform mitigation strategies more quickly,” the authors wrote. “The ability to perform targeted and nonlethal sampling of bats for WNS offers a needed tool to facilitate enhanced surveillance and research for this disease.”

Getting a handle on white-nose is something of a wildlife conservation emergency these days. First discovered in a cave in New York in only 2006, by the recent end of the 2013-2014 hibernating season it had spread to—incredibly—25 states and five Canadian provinces, from New Brunswick to North Carolina and as far west as Missouri (see map below). It doesn’t show any signs of stopping, but being able to track the spread quickly and benignly is a great step toward stopping that spread in its tracks. – Dave Levitan | June 3 2014A map of white-nose syndrome in bats

Source: Turner GG, Meteyer CU, Barton H, et al (2014). Nonlethal screening of bat-wing skin with the use of ultraviolet fluorescence to detect lesions indicative of white-nose syndrome, Journal of Wildlife Diseases. DOI: 10.7589/2014-03-058.

Image:, Vitalii Hulai