In case you haven’t noticed – and unless you’re a fanatic spelunker or wildlife viewer there’s a good chance that you haven’t – the bats of North America are all dying. Beginning just five years ago, an odd illness was discovered in a single bat population in a cave in New York. Today, that disease has spread to at least 16 other US states and four Canadian provinces, decimating bat populations in its wake.
The illness is characterized by lesions on the animals’ wings and a fluffy white outgrowth on the nose. This has caused it to be dubbed, “White Nose Syndrome.” Scientists still don’t understand exactly why the bats rouse and fly around when they should be conserving energy, which is the main reason for the diseases high mortality rate of 90%. But after having burned their fat, they eventually starve to death.
Over the past three years, bat biologists estimate that one million bats have died from WNS in the United States, with some hibernation sites losing 90–100% of their animals. And while they’re still not sure exactly how the pathogen works on the animals, they do now know the culprit with 100% certainty.
The finger is being pointed at a fungus called Geomyces destructans. For a while, some scientists argued that the fungus could not be causing the deaths alone and that some other virus or unseen variable must be at work. This is because bats in Europe also contract symptoms from the same fungus, but none of them are dying.
But in a paper published today in Science magazine, scientists from the U.S. Geological Survey, the University of Wisconsin-Madison, and other institutions showed that G. destructans alone is enough to create all of the symptoms seen in the wild.
The team took two groups of bats. One group was exposed to the fungus directly through laboratory means. The second group was merely kept living in the same space as another group of bats that already had the disease. The group directly exposed all contracted the disease. And except for two individuals, the group just living with the sick bats all contracted the disease as well.
“By identifying the causative agent of white-nose syndrome, this study provides information that is critical for developing management strategies to preserve vulnerable bat populations and the ecosystem services that they provide in the U.S. and Canada,” says study author David Blehert, a microbiologist at the Wildlife Health Center, and a honorary fellow at the School of Veterinary Medicine at UW-Madison.
Now that the perpetrator is known, scientists can focus on exactly how the fungus kills the bats in an attempt to counteract it. But in the meantime, not much can be done besides trying to isolate healthy caves by keeping visitors and explorers from wandering the caves, as people are more than capable of spreading the disease as well.
“Disease involves the interaction of the pathogen, the host and the environment,” said Jeffrey Lorch, a graduate student in the UW-Madison Molecular and Environmental Toxicology Center, another contributor to the study. “And understanding their interactions will be essential for mitigating the effects of white-nose syndrome. Identifying G. destructans as causing the disease will help direct future research toward elucidating what makes the fungus pathogenic, what makes North American bats susceptible, and what environmental factors are important for disease progression and transmission to take place.”