Bat-killer fungus at Md. borders

Infection hits tiny mammals, valued for their insect consumption, during winter hibernation in caves

April 05, 2009|By Frank D. Roylance | Frank D. Roylance,

White-nose syndrome, a deadly fungal infection that has devastated bat populations in New York and New England in the past two years, has now spread to three states on Maryland's borders - and seems poised to strike here next, biologists say.

"We are surrounded on all sides," said Aimee Haskew, a faculty research assistant at the University of Maryland's Appalachian Lab in Frostburg. "It's like a guillotine hanging above your neck."

An outbreak here could destroy one of the largest hibernating populations surviving in the East of the globally rare Eastern small-footed myotis and gradually wipe out larger bat populations that help to control Maryland's insect pests.

Surveys of 10 Maryland hibernation sites this winter found no signs of the disease. But after reports in recent months that it has struck in Pennsylvania, West Virginia and Virginia, biologists fear that its appearance in this state is only a matter of time.

"I have to admit I was shocked. ... These were huge leaps," said Dan Feller, a western region biologist with the Maryland Department of Natural Resources. "It may be some indication that the fungus has been spread, possibly, by cavers. ... We are well within bat range now, from sites in West Virginia and Pennsylvania."

As creepy as some people find them, bats play important roles in plant pollination, seed dissemination and pest control. One little brown bat can consume 1,000 mosquito-size bugs in an hour. Their appetite for pests spares U.S. farmers an estimated $1 billion a year in crop losses and insecticide costs.

White-nose syndrome first appeared in 2006, in a cave near Albany, N.Y. Hibernating bats were found with a white substance on their faces and wings. All were emaciated; many were dead.

Some were clustered near the cave entrances or flying nearby long before they should have left hibernation and before enough insects had emerged to sustain them.

Genetic analysis revealed the fungus to be an unknown member of the cold-loving Geomyces genus. A similar fungus has been seen on bats in Europe, but it has not killed them, Haskew said. It's possible the fungus was somehow transported into North America and began spreading among native bats that have no natural resistance.

The fungus is not known to affect humans, and scientists are only beginning to learn how it affects bats. Some suspect it is an irritant that causes them to awaken frequently during hibernation. A Bucknell University study found that infected bats were waking every two to three days. Disease-free bats rouse every 10 to 18 days.

The frequent disruptions apparently cause the bats to burn too much body fat. They leave the cave too soon in search of food that isn't there, and they starve.

By 2007, the contagion had spread to more caves in upstate New York. By late winter 2008, it was devastating hibernation sites, or hibernacula, in Vermont, Massachusetts and Connecticut. Hundreds of thousands of bats died, 90 percent to 100 percent of each colony.

Inspections this winter have confirmed more white-nose bat mortality in mines and caves in northwestern New Hampshire; northern New Jersey; Lackawanna, Mifflin and Luzerne counties in central Pennsylvania; and four sites in Pendleton County, in West Virginia's eastern panhandle.

In western Virginia, bats in Bath and Giles counties have been found with the white fungus on their faces and wing membranes. Those cases are listed as "likely," pending lab confirmation.

Why Maryland bats have been spared so far isn't clear. Feller thinks it might be because Maryland caves are not interesting enough to attract cavers active in affected areas of the country.

Unlike Maryland's hibernacula, the Virginia caves are "large, complex systems that are extremely popular with cavers," Haskew said. Cross-checks of the logbooks cavers sign have found instances of people visiting the West Virginia and Virginia caves after exploring the "ground zero" cave in New York where the outbreak began.

On March 26, the U.S. Fish and Wildlife Service urged cavers to "curtail all caving activity in WNS-affected states and adjoining states." And when exploring elsewhere, cavers should use clothing and gear that has never been used in white-nose affected states, or in states adjoining them, the agency said.

The government, and such cavers' groups as the Northeastern Cave Conservancy and the National Speleological Society, are urging people to stay out of bat hibernacula in winter. They've issued detailed protocols for cleaning and decontaminating clothes and cave gear. Caving groups also have closed some of the caves they own or control during bat hibernation.

Peter Youngbaer, white-nose liaison for the speleological society, said caving groups are also conservation organizations. A cavers' "Crawlathon" in Kentucky was canceled in January with just three days' notice out of concern that some of the 700 participants might bring the fungus into the state.

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