By Zach Howard
NORTH CONWAY, Mass (Reuters) - A cold-loving fungus already linked to a devastating disease that has killed more than a million bats in the eastern United States definitively causes the fast-spreading malady, officials said on Wednesday.
A study by the U.S. Geological Survey, conducted at its National Wildlife Health Center in Wisconsin and published in the journal Nature, provides the first direct evidence that the fungal pathogen Geomyces destructans causes white nose syndrome in bats, the USGS said.
The finding should help experts develop ways to preserve vulnerable U.S. and Canadian bat populations and their ecosystems, Anne Kinsinger, associate director of Ecosystems at the USGS, said in a statement.
The syndrome gets its name from the white fungus that settles in tufts on infected bats' muzzles and invades their skin.
It causes them to use limited body-fat reserves, retreat deeper into chilly caves or exhibit odd behavior, such as flying in daytime and cold weather, when insects they eat are not found.
Wildlife officials have said little-brown and tricolored bats are the ones worst hit in the nation so far by white nose, and the endangered Indiana and Southeast-based Gray bats could potentially be acutely affected as well.
White nose is mainly spread bat to bat, but humans can transport fungal spores via clothes and gear from contaminated sites, such as caves and mines. People can help slow the spread by staying out of sites that are homes to bats.
In the USGS study, all healthy little brown bats exposed to the fungus while hibernating in captivity developed the disease, the agency said. The experiment also demonstrated that the fungus can be spread bat-to-bat in a given population.
Since its discovery in an upstate New York cave in 2006, white nose has been confirmed in about 16 states and four eastern Canadian provinces, and it appears to be steadily trekking westward.
Earlier this year, officials said Oklahoma was the furthest west the fungal pathogen has been detected, while full-blown white nose has gone as far west as Kentucky and Tennessee.
Experts suspect the fungus may have been brought to the United States from Europe by a person inadvertently carrying its spores on shoes, clothing or other gear. Evidence of a similar fungus has been discovered in Europe, they said.
Experts say diminishing populations of bats, an important predator of insects, could have harmful consequences for humans.
North America's loss of bats, a key predator of mosquitoes, beetles and pests that can harm plants, could cost agriculture at least $3.7 billion a year, according to a study published in the journal Science in April.
Scientists have predicted the disease could wipe out some bat species in New England within 15 years.
About a dozen species out of a total 45 U.S. bat species are affected by white nose, which is nearly half of the 26 bat species that are cave-hibernating bats. In some Northeast caves, 90 to 100 percent of populations have died. About 1,100 bat species exist worldwide.
(Reporting by Zach Howard; Editing by Cynthia Johnston)