One of the first hints that yet another fungal disease that could devastate wildlife was emerging in the United States came in 2006 with a report that an isolated winter den of timber rattlesnakes in New Hampshire had suffered a population crash.

Those snakes were on the far northern edge of their species’ habitat, and showed signs they had suffered from inbreeding. But they also had skin lesions, often called hibernation blisters or hibernation sores, that caught the attention of scientists.

Similar cases popped up in Massachusetts, said Jeffrey Lorch, a microbiologist at the United States Geological Survey’s National Wildlife Health Center in Madison, Wis. Then rattlesnakes in Illinois, called massasaugas, began to suffer.

“People started being on the lookout,” he said. The health center started getting a lot of calls.

By 2009, Ophidiomyces ophiodiicola, the fungus that causes the lesions, had been named. And it has been found to infect more than two dozen species of snakes in this country.