The fungus, which is harmless to humans and other animals, is known popularly as white nose syndrome for its tendency to make bats’ muzzles look like dandelions about to go to seed. It threatens some nine bat species that hibernate in Long Cave, a 1.3-mile-long den of crucial, undeveloped habitat just five miles from the entrance to the park’s Mammoth Cave, which is visited by nearly half a million people a year, officials said.
Sarah Craighead, the park superintendent, said that on Jan. 4, a biologist harvested a bat near the entrance to Long Cave with the telltale symptoms.
“I am incredibly sad to report that the bat was infected with white nose syndrome,” she said. “And that this is a condition that is deadly to bats.”
First discovered in an upstate New York cave in 2006, white nose syndrome has killed 5.5 million bats across 19 eastern states and four Canadian provinces, scientists say. Spores from the fungus, known as Gomyces destructans, have been found in 21 states. While the disease is mainly spread among bats, humans can transport the spores in dirt clinging to the soles of shoes and on clothes.
Park officials had regularly checked Long Cave, which has a far denser bat population than nearby Mammoth Cave. Steven Thomas, the biologist who found the first infected bat in the park, said that scores of infections usually follow the first.
“We did not see any other bats with symptoms of white nose,” he said. “I did not go back in the cave for fear of disturbing the bats.”
Federal officials in Great Smoky Mountain National Park and Acadia National Park, as well as state and regional governments throughout the nation have imposed new restrictions on spelunking in an effort to prevent humans from spreading the spores.
Since 2009, officials at Mammoth Cave National Park have taken precautions like requiring all tourists to clean their footwear and researchers to disinfect their clothing with Lysol. Until this month, the closest confirmed case of white nose syndrome was in a cave some 50 miles away in Breckenridge County, Ky.
The fungus interrupts bats’ hibernation, scientists say: infected animals are often seen flying outside in broad winter daylight, where they have been known to try and enter human homes. Some scientists believe that the bats die because the infection forces them to burn precious fuel reserves by flying in cold weather, as opposed to hibernating in caves with their wings wrapped around them, conserving calories and electrolytes.
“It increases the potential that bats and people might interact,” said Kevin Castle, the National Park Service’s white nose syndrome coordinator.
In some caves where the fungus has lived for more than a year, bat populations have plummeted by 90 percent, while some mines have seen bat populations “completely wiped out,” said Jeremy Coleman, the national white nose syndrome coordinator for the Fish & Wildlife Service.
The disease could have a devastating impact on endangered Indiana bats and gray bats, for which Long Cave is a stronghold. Populations of northern long-eared bats and tricolored bats have also plummeted across the eastern United States because of white nose syndrome. The population of little brown bats, once the most common bat in North America, has plummeted.
“We don’t know at this point if the numbers we’re seeing are enough to sustain that population’s long term survival,” Dr. Coleman said.
Four species of tree-dwelling bats that live in Mammoth Cave National Park appear unaffected by the disease.
While scientists don’t know the origin of the white nose syndrome fungus in America, they note that similar microbes are common in Europe, suggesting that the spores may have been imported. Because the fungus thrives in cold temperatures, it is can survive inside caves for years.
Despite the grim prognosis for bats in Mammoth Cave National Park, Ms. Craighead said the crisis presents an opportunity to educate the public about the ecological role of bats.
“The number of North American bats estimated to have died from white nose syndrome thus far had the capacity to consume up to 8,000 tons of insects per year,” she said. “Bats are an important and misunderstood part of our ecosystem.”