A Fungal Disease Ravaged North American Bats. Now, Researchers Found a Second Species That Suggests It Could Happen Again White-nose syndrome caused millions of bat deaths, and scientists are sounding the alarm that a second fungus could be disastrous if it reaches American wildlife Lillian Ali - Staff Contributor May 30, 2025 A little brown bat (Myotis lucifugus) is seen with white fuzz on its nose, a characteristic of the deadly white-nose syndrome. Ryan von Linden / New York Department of Environmental Conservation In February 2006, a cave explorer near Albany, New York, took the first photograph of bats with a mysterious white growth on their faces. Later, biologists studying the mammals in caves and mines discovered piles of dead bats in the state—also with the fuzzy white mold. The scientists were floored. For years, no one knew what was causing the mass die-offs from this “white-nose syndrome.” In early 2007, Albany residents called local authorities with reports of typically nocturnal bats flying in broad daylight. “They were just dying on the landscape,” wildlife biologist Alan Hicks told the Associated Press’ Michael Hill in 2008. “They were crashing into snowbanks, crawling into woodpiles and dying.” At last, scientists identified a culprit: The bats had succumbed to an infection caused by the fungus Pseudogymnoascus destructans. Since its initial discovery, white-nose syndrome has killed millions of bats across 40 U.S. states and nine Canadian provinces, making it “the most dramatic wildlife mortality event that’s ever been documented from a pathogen,” DeeAnn Reeder, a disease ecologist at Bucknell University, tells the New York Times’ Carl Zimmer. Now, nearly two decades later, scientists have developed some promising ways to fend off the disease, including an experimental vaccine. But a new study published this week in the journal Nature warns of a newly discovered second species of fungus that, if it reaches North America, could set all that progress back. “We thought we knew our enemy, but we have now discovered it is twice the size and potentially more complex than we had imagined,” lead author Nicola Fischer, a biologist at the University of Greifswald in Germany, says in a statement. Little brown bats are susceptible to white-nose syndrome in North America. Krynak Tim, U.S. Fish and Wildlife Service The team analyzed 5,479 fungus samples collected by hundreds of citizen science volunteers across North America, Asia and Europe. They found that white-nose syndrome is caused by two distinct fungal species native to Europe and Asia, with only one species having reached North America so far. If the second species hits the continent, it could look like a “reboot” of the epidemic, Reeder tells the New York Times. Study co-author Sébastien Puechmaille, an evolutionary biologist at the University of Montpellier in France, knew bats in Europe had also been seen with white fuzz on their noses, as he tells the New York Times. But those populations didn’t die off like American bats. Charting the disease across Europe and Asia, he noticed that the fungus was able to live alongside those bats, while it ravaged American ones. In its native range, the fungus grows in the bodies of hibernating bats as their internal temperature drops, then it’s shed in the spring when they awaken. But in American bats, the fungus causes their immune systems to activate and burn fat reserves as they hibernate. The bats then wake up periodically, causing irregular activity and eventual starvation. The researchers suggest the damaging fungal spores were first brought to North America by cavers that traveled from Europe—potentially western Ukraine—to the United States without completely disinfecting their boots or rope. White-nose syndrome poses a threat not just to bats, but to whole ecosystems. Bats are vital parts of many food chains, eating insects and pollinating plants. However, they reproduce fairly slowly, only having one or two pups at a time. Rebuilding a bat population, then, could take decades. And since cave ecosystems are similarly delicate, biologists are wary of trying to kill off the fungus preemptively. “Cave ecosystems are so fragile that if you start pulling on this thread, what else are you going to unravel that may create bigger problems in the cave system?” said University of Wisconsin–Madison wildlife specialist David Drake to the Badger Herald’s Kiran Mistry in December. The discovery also occurs as the original wave of white-nose syndrome continues to spread across North America, having just crossed the Continental Divide in Colorado. Just one spore of the new species could be devastating to American bat colonies. Puechmaille tells the New York Times that policies should be put in place to make sure the second fungus does not spread to more continents, and that cavers should not move equipment between countries and should disinfect it regularly. “This work … powerfully illustrates the profound impact a single translocation event can have on wildlife,” he adds in the statement. Get the latest stories in your inbox every weekday.