Researchers confirmed that a cold-loving fungus is responsible for white-nose syndrome (WNS), the epidemic rapidly wiping out bats in eastern North America. The results were published last week in Nature.The fungus, Geomyces destructans, was first described in 2009. It is found on the wing membranes and muzzles of hibernating bats, many of which rouse early only to die of starvation or exposure. Since WNS was first documented in 2006 in a cave in upstate New York, it has spread to at least 16 other states and four Canadian provinces. WNS has killed millions of bats belonging to six species, including the common little brown bat (Myotis lucifugus) and the highly endangered Indiana bat (Myotis sodalis).This new study confirms that the fungus is the cause of WNS, not just a symptom or an associated opportunistic infection. Microbiologist David Blehart and colleagues showed experimentally that exposure to G. destructans alone can cause the disease, and that it can be transmitted bat to bat.The researchers collected healthy little brown bats from an area free of WNS and housed them in lab refrigerators with the same temperature and humidity typically experienced by hibernating bats. Twenty-nine bats were infected by direct administration of G. destructans spores to their skin; one hundred days later, all of them had WNS. In the same time period, sixteen of an eighteen additional bats housed with infected bats came down with the disease.Now that the culprit has been identified, conservation and research efforts can be streamlined. Just days before this study was published, the US Fish and Wildlife Service (FWS) committed up to $1 million for funding WNS research. The agency has also closed off some caves in affected areas for fear that people may be unwittingly spreading fungal spores into new caves. WNS needs to be contained before it spreads to western states, where more dozens more bat species may be at risk.Bats are not the first wildlife to face potential extinction by infection. The recent worldwide decline, and multi-species extinction, of amphibians was due to an introduced fungal disease. However, it took two decades for scientists to publish the first evidence of fungus-related amphibian decline, and another decade before the research community organized to develop a global policy response to the threat. I am hopeful that the speed with which scientists and conservationists are mobilizing resources and publishing data on WNS reflects a large public concern for American bats and will translate into their future protection.