A mysterious bat-killing disease that has swept across the eastern U.S. in recent years officially reached Missouri on Monday -- the first confirmation west of the Mississippi River.
Three bats collected from two public caves in Lincoln County, about an hour north of St. Louis, tested positive for white-nose syndrome at a U.S. Geological Survey National Wildlife Health Center laboratory in Madison, Wis.
The discovery in Missouri of white-nose syndrome, named for a white fungus that forms on the muzzle and wings of infected bats, doesn't surprise biologists and only further confirms that the disease is continuing to spread despite the best efforts to contain it, said Jeremy Coleman, national white-nose syndrome coordinator for the U.S. Fish and Wildlife Service in Hadley, Mass.
The disease has spread to 19 states and four Canadian provinces since the first case was documented near Albany, N.Y., in 2006.
Its effect on bat populations has been devastating. A January study by Fish and Wildlife Service biologists estimates as many as 6.7 million bats across the eastern U.S. have died. In some places, bats are dying at such a rate that biologists fear some species won't survive.
"The mortality rates in the east where this has been happening are staggering," said Tony Elliot, a Missouri Department of Conservation bat biologist.
Evidence of the fungus that causes the disease was first detected in Missouri in April 2010 in a little brown bat found in a private cave in Pike County. The disease was suspected in five federally endangered gray bats and in a northern long-eared bat netted outside a public cave in Shannon County a month later.
But Monday was the first time that white-nose syndrome was officially confirmed in Missouri.
The infected bats in Lincoln County -- a little brown bat and two tri-colored bats -- were discovered as part of a Department of Conservation surveillance and monitoring program.
The two caves are closed to public access and their specific locations aren't being disclosed to prevent human disturbance of any remaining bats.
"Disturbing bats in caves while they roost or hibernate can increase their stress and further weaken their health," Elliott said.
While there is little doubt that white-nose syndrome is devastating to bat populations, scientists aren't sure exactly how.
One hypothesis is that the fungus disrupts bats' hibernation, depleting fat reserves and causing starvation. It's also possible that bats are dying of dehydration or that the fungus is making them more susceptible to predators.
"It might not be as simple as one answer," Coleman said. "It might be multiple things."
Whatever the reason bats are dying of white-nose syndrome, it's not just concerning for biologists and conservationists, but also farmers and forest managers.
Bats provide natural pest control for farms and forests and help control insects such as mosquitoes that spread disease to people. For instance, Missouri's 775,000 gray bats eat more than 223 billion bugs per year, or about 540 tons.
"The economic impact would be just as tremendous as the biological impact," said Paul McKenzie, endangered species coordinator for Fish and Wildlife Service's Columbia, Mo. field office.
White-nose syndrome spreads primarily through bat-to-bat contact and hasn't been found to infect humans or other animals. But scientists believe it may also be transmitted by humans inadvertently carrying the fungus from cave to cave on clothing and gear.
Many public caves in Missouri have been closed, at least seasonally, to prevent the spread of this disease. But almost three-fourths of Missouri's 6,300 caves are privately owned.
State and federal agencies have been working with conservation groups and private cave owners to address the threat of white-nose syndrome, including the use of screening and decontamination protocols to minimize the risk of human transmission.
Biologists say there's no way to stop the spread of the disease. The only hope is to slow it down.
Said Coleman: "Right now the only thing we have in our toolbox is containment."
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