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White-Nose Syndrome comes to Missouri

This article first appeared in the St. Louis Beacon, April 3, 2012 - The Missouri Department of Conservation confirmed April 2 that White-Nose Syndrome (WNS), a deadly disease that has decimated bat populations in the Northeast, has been found in Missouri bats. It is the first known incidence of WNS west of the Mississippi.

The disease was detected in two tricolor bats and one little brown bat in caves in Lincoln County. While the disease-causing fungus, Geomyces destructans, was discovered growing on bats in Missouri in Pike and Shannon Counties in 2010, the bats tested in 2010 did not exhibit WNS, which is characterized by white growth of the fungus on the face, ears and wings of affected bats. The fungus is not thought to affect humans.

“The mortality rates in the east, where they have been hit the hardest, are staggering,” said MDC bat biologist Tony Elliott. Some eastern U.S. bat populations have been reduced by as much as 95 percent by the disease, he said.

Given that the disease has killed more than 5 million bats in the eastern United States since it was detected in New York caves in 2006, and has spread to 19 states and four Canadian provinces, the finding bodes ill not only for Missouri bats, but for bats in Western states, many of which have overlapping ranges.

“There are a lot of bat species that occur only in the Western United States,” said Ann Froschauer, national WNS communications leader for the USFWS. Western bats, she said, often share ranges with Missouri bats, increasing the likelihood of transmission.

Cause of Death

Just as the timeline of the disease is not clear to researchers (how long bats carry the fungus before they develop the syndrome), scientists are researching exactly what causes bats to succumb.

Growth of the fungus on wings damages wing membranes, disrupting homeostasis and leading to dehydration, said Anne Ballman, a wildlife disease specialist for the U.S. Geological Survey. Bats may be starving themselves by moving around unnecessarily, depleting fat stores during the hibernation period.

Moreover, impaired bats with tattered wings are much more likely to be eaten by crows, red tailed hawks and ravens, said Jeremy Coleman, a biologist for the U.S. Fish and Wildlife Service.

Slowing the Spread

To contain the spread, the Missouri Department of Conservation has formed a working group that includes the Department of Natural Resources, Missouri State Parks, the U.S. Fish and Wildlife Service and the National Parks Service, said Elliott.

“The main thing that has been addressed so far is looking at different cave closure options,” said Elliott. While public caves in Missouri are already closed, he said, Missouri also is home to numerous “show” caves, privately owned commercial attractions that have thousands of visitors and are not required by law to close.

The WNS Working Group is interacting with such cave owners and operators to deter human spread of the fungus by unwitting visitors, who might unknowingly carry the fungus from cave to cave.

Human Vectors

While bats are considered to be the number one vector of WNS, carrying spores and actively growing fungus from hibernacula (bat cave) to hibernacula, humans may also pick up the fungus on caving gear, shoes and other articles brought into multiple caves, unwittingly transmit it to other caves.

In fact, Froschauer said, research has shown that Geomyces destructans originates in Europe, and has been found growing on European bats without apparent harm. Since the first incidence of WNS occurred in Howe’s Cave, a tourist attraction in Upstate New York, Froschauer said, it is likely that the original fungus traveled from Europe on somebody’s shoe or gear. People have the ability to spread the disease far and wide.

“A hiker flying [from Missouri] to Seattle and going into a cave in Washington with spores on his shoes,” Froeschauer said, could create a “new epicenter” of the epidemic.

“Don’t move your gear back and forth,” she said. “It’s something to be thoughtful about.”

Decontamination and control

In addition, the U.S. Fish and Wildlife Service has posted decontamination guidelines for those bringing gear into and out of caves using ordinary household products such as Lysol to rid boots and other gear of the fungus.

While scientists and governmental entities are searching for other ways to stop the spread of WNS, they have not yet found a fungicide or pharmaceutical that will “inhibit the growth of the fungus and not be detrimental to the bats,” said Coleman.

“We are aiming at slowing the spread and reducing the risk involved,” he said. “Our best hope would be to slow it.”

Hilary Davidson is a freelance writer.