Seeking the origin of white-nose syndrome

While researchers still struggle to find precisely where the fungus that causes white-nose syndrome in North American bats originated, scientists recently found a few clues.

In a new study published in mBio, researchers were able to confirm the disease has only recently reached North America in the past couple decades and that it most likely spread from Europe.

“We wanted to figure out where the fungus came from — if it came from a specific place, you can figure out how it got here,” said TWS member Jeff Foster, an associate professor at Northern Arizona University and the senior author of the recent study. “We wanted to find potential ways to manage for the disease, but since we can’t put this genie back in the bottle, we also wanted to figure out if clues from the introduction of white-nose syndrome can prevent future introductions of other pathogens.”

In the study, Foster and his colleagues sequenced entire genomes of the Pseudogymnoascus destructans fungus that causes white-nose syndrome. They also developed a panel of microsatellite markers from fungal cultures taken from swabbing hundreds of bats as well as environmental swabs from caves in North America, Europe and Asia. “We threw the whole kitchen sink at it genetically trying to figure out the source,” he said. “But we couldn’t figure out exactly where it came from.”

While they didn’t find the definite source cave of the fungus, they uncovered some important findings about white-nose syndrome. They determined the fungus is genetically diverse throughout Eurasia.

“In some ways, it isn’t too surprising because the fungus has been present throughout Eurasia for a long period of time, and it’s been associated with bats for much of that time,” Foster said. While it’s difficult to determine the timing of the evolutionary history of many fungi, researchers believe the fungus has been in Eurasia, and likely on bats, for millennia.

In the U.S. and Canada, Foster and his colleagues found virtually no genetic diversity in the fungus samples collected, suggesting it was a very recent introduction. Moreover, the genetic data suggest that bats are moving the fungus very long distances.

Foster and his colleagues are pretty confident that the fungus came to North America from Europe, “but we just don’t know where in Eurasia it came from,” he said.

While Foster and his colleagues continue to seek the origin of the disease, they hope to address some other questions regarding the fungus, such as how bats evolve resistance. While in North America, white-nose syndrome has decimated millions of bats as it spreads across the country, Eurasian bats seem to fight off the infection. Surviving bats in the U.S. and Canada give hope that bats are finding a way to live with this infection and perhaps begin the slow process of repopulating areas decimated by the disease, he said.