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Science and the Environment

No White-Nose Syndrome in Bats in Sequiota Cave; Biologists Continue to Monitor the Disease in

Good news for the bats at Sequiota Park in Springfield:  laboratory test results show no evidence of white-nose syndrome among the bat population in the cave there.  Lab samples were taken from the Sequiota Park Cave March 26thfollowing the unusually early migration of a colony of gray bats, which lives in the cave during the summer.  Researchers at the U.S. Geological Survey’s National Wildlife Health Center in Madison, Wisconsin examined the samples under microscope and through DNA-sequencing.  Both tests came back negative.

But last week, white-nose syndrome was confirmed in Missouri.  Three infected bats were found in two public caves north of St. Louis in Lincoln County.

Biologists in the state have been working for some time to address the threat of the illness. 

Tony Elliott, resource scientist and bat biologist with the Missouri Department of Conservation, says the confirmation last week of the disease in the state was not a surprise.  The presence of the fungus that causes the illness was detected in Missouri in the spring of 2010.

According to Elliott, white-nose syndrome is caused by the fungus geomyces destructans, which was unknown to science before the advent of the illness in 2007…

"The fungus grows on bats as they are hibernating in caves.  It's a cold-loving fungus, and it grows on the exposed skin, the nose, the wing membranes, the tail membranes of the bats.  And it actually penetrates the skin layer, which is different than most surface fungal infections like athlete's foot or things like that."

The fungus breaks down the skin of bats.  Biologists aren’t sure exactly what causes the infected bats to die.  It might be that bats with white-nose syndrome wake up during hibernation to try to combat the growth of the fungus and use up precious fat reserves that they need to get them through the winter.  Or it might be due to the deterioration of a bat’s wing and tail membranes…

"which are important to bats for maintaining water balance and some gas exchange type of activities during the hibernation period."

There is evidence that bats can survive the disease.  Studies have found bats with heavy scarring on their wings—a sign that they’ve beaten white-nose syndrome.

The current estimate is that between five and  a half and six and a half million bats have been killed by white-nose syndrome in North America since 2007…

"At individual sites they have seen ranging usually from 70% to even 100% mortality at a particular site at a cave where all of the bats died or  or at least 70% of the bats using that cave died."

Currently there’s no cure for white-nose syndrome.  Infected bats that are brought out of hibernation into captivity and provided with food and water can fight the illness.  And bats that are infected near the end of hibernation can recover.

The fungus doesn’t appear to affect other mammals.  Elliott says that’s because the growing fungus cannot survive temperatures above 54 degrees.  The body temperature of bats drops low enough during hibernation to allow the fungus to thrive.

Elliott is concerned for the future of bats in the United States…

"There's been some modeling in the northeast part of the U.S. that suggests that little brown bats, which were the most common bats in that region, could become extinct--extirpated from that region--in as few as 15 years, and that modeling was done, I believe, in 2010."

And, although the endangered Indiana bat hasn’t been impacted as much as the little brown bat, there’s concern for it, too…

"The Indiana bat has not been suffering quite as high a mortality rate as the little brown bat, but it was not doing very well as a species before white-nose arrived.  There's real concern about the possibility that this could be the straw that broke the camel's back when it comes to Indiana bats."

The loss of millions of bats has a significant impact on our eco-system since the flying mammals are extremely beneficial.  Elliott says they’re the main predator of night-flying insects…

"In Missouri we estimate that just one species of Missouri's bats, the gray bat, could eat over 540 tons of insects a year.  A lot of those insects are agricultural pests, forestry pests and mosquitoes, things like that."

According to Elliott, part of the hope of slowing the geomyces distructans fungus is that nature can come into some sort of balance.  But he says the faster it moves, the less likely that is to happen.

Prevention is the focus right now.  Steps have been taken to eliminate the spread of the fungus by humans.  There are suggested decontamination protocols to follow before someone enters a cave.  Most caves on public land in Missouri have been closed to the public.

Landowners with caves on their properties are asked to closely monitor who enters their caves to try to avoid bat disturbance.

Elliott says most of the management steps that are going to be taken in Missouri have already been taken.

He says, now that white-nose syndrome has been confirmed in Missouri, the Department of Conservation may get involved in research such as finding potential treatments and determining how the disease progresses once it first arrives at a location.  And they’ll continue to track the progression of the illness in the state.  A group has been formed—the Missouri White-Nose Working Group—to study the topic.