Bat-killing white-nose syndrome moves southeast

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White-nose syndrome has killed 7 million bats, Photo courtesy U.S. Geological Survey.

New infections found in Georgia, South Carolina

By Summit Voice

SUMMIT COUNTY — The spread of a lethal bat disease to Georgia and South Carolina once again heightens concerns that humans may be implicated in the transmission of the fungal spores that cause white-nose syndrome.

State and federal officials announcing the discovery of the disease in southeastern bat populations warned that there’s growing evidence that humans are a factor in the spread. White-nose syndrome has now spread to 22 states and 5 Canadian provinces over the past seven years.

The most recent discovery of the disease was made at two caves in Dade County, Ga. — one in the Chickamauga and Chattanooga National Military Park, operated by the National Park Service, and the other at Cloudland Canyon State Park. Last year the bat disease was documented on the Tennessee side of the same national military park.

“White-nose syndrome’s attack on North American bats is continuing unabated,” said Mollie Matteson, a bat specialist at the Center for Biological Diversity. “Unfortunately, despite the disease’s relentless push across the country, the response of state and federal wildlife agencies has been astonishingly passive.”

The bat disease, first documented in a cave in upstate New York in 2006, has spread as far west as Missouri. In the past month, it was reported for the first time in Illinois and Prince Edward Island, Canada. Biologists estimate it has killed nearly 7 million bats; so far it has affected seven species, including two that are federally endangered, the Indiana bat and the gray bat. Scientists fear the continued spread of the disease, which strikes bats during hibernation, will lead to the endangerment and possible extinction of many of North America’s two dozen hibernating bat species.

There is no cure for white-nose syndrome, which is caused by an introduced fungus, almost certainly from Europe, where the fungus is found but does not make bats sick. According to Matteson, scientists have collected compelling evidence that the fungus was brought to North America by cave visitors.

Given that humans may be carriers of the spore, Matteson said resource managers need to do much more to protect as-yet unscathed bat populations in he West, including stricter cave management rules and even closures of caves, a strategy deemed ineffective by cave-access groups.

Caves on U.S. Forest Service and National Park Service lands in Georgia have been closed to nonessential access since 2009.

“It’s chillingly clear that the next frontier for this devastating disease is the western United States and the many, many bat species that live there,” Matteson said. “But even now, our government officials keep allowing cave visitors to come and go in most western caves on federal land, as though nothing has changed in the past seven years. That needs to stop, or bat populations across the West may crash.”

The epidemic’s impacts are not limited to bats. Scientists estimate that the value of bug-eating bats to U.S. farmers ranges from $3 billion to $53 billion per year. Bats eat enormous quantities of moths, beetles, mosquitoes and other insects, and their absence could make farmers and others decide to use greater quantities of expensive, and potentially harmful, pesticides.

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3 Responses

  1. Once again,the statement that there is “growing evidence that humans are a factor in the spread” of WNS is unsupported by any research, attribution, or citation. In fact, the opposite is true.

    To date, the only proven method of WNS transmission is by physical bat to bat contact. (U.S. Geological Survey’s National Wildlife Health Center lab, experiments described and published by Lorch, et al in Nature, Oct. 26, 2011).

    Scientists still do not know how many spores it takes to cause the disease (epidemiologists call this the Multiplicity of Infection, or MOI). Lab inoculations are given in the 500,000 range, where in-cave experiments have shown that tourists constantly pick up and drop (as we all do when we walk around) in the neighborhood of 50,00 – 60,000 spores of all kinds, much less of Geomyces destructans.

    Finally, most every new report of WNS comes from caves or mines that have been closed to the public for years. Closing caves – that is, putting up a sign, or locking a bat-friendly gate – doesn’t prevent the spread of the disease, as the bats ignore government warnings, signs, and gates. They’re spreading this themselves along expected bat travel routes.

    In a just-published study in the Journal of Cave and Karst Studies, by V. Shelley, et al, the authors state, “At this time, no information is available about spore loading during human
    visits to a cave or the minimum infective dose of G.destructans
    to initiate WNS in bats or contaminate the cave environment. The spread of WNS along bat migration routes (Frick et al., 2010) and the lack of numerous geographic epicenters may also suggest that human-vectored transport of G. destructans may be rare.”

    It’s time we stopped listening to the fear-mongering being spread by the Center for Biological Diversity, calling for over-reaction by federal and state land management agencies, and allowed our responses to be driven by hard science.

    Unfortunately, to date that hard science is telling us we may not be able to do anything about this disease, except to help affected colonies recover. Scientists have been working to see if physical interventions, or chemical or biological treatments would help. They haven’t. While certain substances kill the fungus, they also kill the bats, or the handling necessary to apply the materials kills the bats, or the risks of contamination of other cave obligate species and groundwater are too high.

    Not all bat species are affected the same – and many not at all. Understanding those nuances is important. It can help us with conservation measures, such as protecting maternity roosts, building bat houses for summer use, and avoiding disturbing surviving bats during winter hibernation.

    In the meantime, there is other critical cave and bat research that needs to take place, including the development of baseline information about western bat species and behaviors – much of which is unknown due to the vast remote regions of the western U.S.

    A “one size fits all” call by the CBD for blanket cave closures is off point, a distraction, proven ineffective in stopping the disease spread, and frankly, counterproductive. It’s time we stopped listening.

    (Since, 2008, Peter Youngbaer has been the White Nose Syndrome Liaison for the National Speleological Society, which has been exploring, studying, and conserving caves in the Unites States for over 70 years. He administers the WNS Rapid Response Fund, which has provided financial support for no less than twenty research projects dedicated to WNS).

  2. [...] “Unfortunately, to date … hard science is telling us we may not be able to do anything about this disease, except to help affected colonies recover,” the National Speleological Society‘s Peter Youngbaer wrote in a comment on a previous Summit Voice story. [...]

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