Deadly Bat Fungus Spreading in U.S.

A deadly fungus responsible for tens of thousands of bat deaths in the eastern United States is on the move, according to recent tests that confirmed the killer's presence in Tennessee.

White-nose syndrome, which appears in hibernating bats, has been linked to a cold-loving fungus found on the wings, ears, and muzzles of infected bats. Until now, the disease has appeared only in caves along the northeastern seaboard from Vermont to Virginia (see a U.S. map).

But today the Tennessee Wildlife Resources Agency announced that two tricolored bats—commonly known as pips—have been found with white-nose syndrome in Worley's Cave in Sullivan County.

"I think this will be furthest south that white-nose syndrome has been detected in the United States, and it may be the furthest west as well," said Gina Hancock, a spokesperson for the nonprofit Nature Conservancy, which has been tracking the disease.

The cave where the two infected bats were found is only about 65 miles (105 kilometers) from a confirmed infection site in Virginia—well within flying range for the pips.

"There's nothing extraordinary about the jump from Virginia to the Tennessee site, except we're disappointed to see it happen," said Alan Hicks, a bat expert at the New York State Department of Environmental Conservation who was not involved in the Tennessee tests.

But if white-nose syndrome spreads through Tennessee, the disease could wreak havoc on several bat populations and may even wipe out two endangered bat species, scientists say.

"The eastern caves don't have many large hibernating colonies," Hancock said. But Tennessee "has up to one hundred thousand or more bats in one cave. With a 95-percent mortality rate, the loss is going to be massive."

Rare Bats at Risk in Tennessee

First identified in 2007, white-nose syndrome is still something of a mystery. It's unclear how the fungus kills or whether it is even the main cause of death in afflicted animals.

Scientists think the disease spreads when bats gather in colonies to hibernate.

The ailment causes bats to wake up during hibernation, which means the animals use up their fat reserves too fast. Sick bats fly out of their caves during winter in a desperate attempt to find food. Because the insects they eat are also seasonally dormant, the bats soon die of starvation.

(Related: "'Drunk' Bats Fly Right—Discovery Surprises Scientists.")

Pips don't generally cluster when they hibernate, so the occurrence of white-nose syndrome in Tennessee may still be relatively isolated. But scientists are concerned that the condition could jump to gray bats and Indiana bats, which are endangered.

The sick pips' cave, for example, is also a gray bat summer nesting ground.

"Gray bats hibernate in very large numbers in very few caves," said Cory Holliday, the Nature Conservancy's cave and karst manager.

"If gray bats are infected, it will probably be a matter of just a couple of years before the global population of gray bats is in severe danger."

Bats: Key Public Servants

People can help control spread of the disease by keeping away from known infection sites and decontaminating any gear used for recreational caving.

"It's not a far-reaching conclusion to think that people can get dirt or fungal spores on their boots and walk into a cave two states away and spread the disease," Holliday said.

White-nose syndrome isn't a direct health risk for humans, he added. But the loss of thousands of bats would have a huge impact on people. (Related: "Bat Bonanza: 100 Species Found in 5 Acres of Jungle.")

Since many bat species primarily eat insects, "bats provide a tremendous public service in terms of pest control," Richard Kirk, the Tennessee wildlife agency's nongame and endangered species coordinator, said in a statement.

"If we lose 500,000 bats, we'll lose the benefits from that service, and millions of pounds of insects will still be flying around our neighborhoods, agricultural fields, and forests."