Once the baseline data are established, “in areas like this where it’s not yet arrived, we can form a predictive model based on ecology, physiology, genetics and skin chemistry,” Dr. Reichard said.

Biologists have considered putting food in caves, or feeding bats probiotics or electrolytes or applying chemical skin treatments to kill the fungus. They have talked about dehumidifiers. In some places they have fogged the caves with antifungal agents such as B-23, which is made from the stems of wild pineapples.

Exposing infected bats to ultra violet light shows promise and is being tested. “UV light can kill the fungus in the lab but we don't have a feasible deployment scheme," Dr. Reichard said.

Dr. Tuttle cautions that such experiments could go awry. “Using something to kill the fungus is going to kill other fungi or microorganisms in the cave that will cause other chain reactions and problems that are far greater than what we started with,” he said. Treated bats may also get reinfected.

While researchers are focused on the here and now, a warming world is expected to play a role in the future of bats, and perhaps this disease, though it’s too early to say how.

“The temperature of a cave is the same as the mean outside temperature,” Dr. Fuller said. “So bats will use more energy while they are in torpor as it warms. Climate change will play a role.”