White nose syndrome
White-nose syndrome (WNS) is a poorly understood disease associated with the deaths of at least 5.7 million to 6.7 million North American bats. The condition, named for a distinctive fungal growth around the muzzles and on the wings of hibernating bats, was first identified in a cave in Schoharie County, New York in February 2006. It has rapidly spread, and as of 2013, the condition had been found in over 115 caves and mines ranging mostly throughout the Northeastern U.S. and as far south as Alabama and west to Missouri and into four Canadian provinces.
According to laboratory research in late 2011, the syndrome appears to be caused by a fungus called Geomyces destructans, but no obvious treatment or means of preventing transmission is known. The mortality rate of some species has been observed at 95%.
The US Fish & Wildlife Service (USFWS) has called for a moratorium on caving activities in the affected areas and strongly recommends that any clothing or equipment used in such areas be decontaminated after each use.
The fungus Geomyces destructans can only grow in low temperatures, in the 4 to 15 °C range (39–59°F). The fungus will not tolerate temperatures above 20 °C (68 °F) and appears to be adapted to attacking hibernating bats. Infection causes bats to rouse too frequently from torpor (temporary hibernation) and starve to death through excessive activity. The symptoms associated with WNS include loss of body fat, unusual winter behavior (including flying), damage and scarring of the wing membranes, and death.
The disease was first reported in January 2007 in some New York caves. It spread to other New York caves and into Vermont, Massachusetts, and Connecticut in 2008. In early 2009 it was confirmed in New Hampshire, New Jersey, Pennsylvania, West Virginia and, in March 2010, Ontario, Canada, and Middle Tennessee. In 2012, new cases showed up in northeastern Ohio, and Acadia National Park in Maine. New confirmed cases appeared in 2013 in Georgia, South Carolina, and Illinois.
Alan Hicks with the New York State Department of Environmental Conservation has described the impact as "unprecedented" and "the gravest threat to bats...ever seen." The mortality rate in some caves has exceeded 90%. A once-common species, the little brown bat has suffered a major population collapse and may be at risk of rapid extinction in the northeastern U.S. within 20 years due to WNS. There are currently nine hibernating bat species confirmed with infection of Geomyces destructans, and at least five of those species have suffered major mortality. Some of those species are already listed as endangered on the U.S. endangered species list, including the Indiana bat, whose primary hibernaculum in New York has been affected. The long-term impact of the reduction in bat populations may be an increase in insects, possibly even leading to crop damage or other economic impact in New England.
Bat colonies have been decimated throughout the northeastern U.S., and the syndrome has spread into mid-atlantic states and northward into Canada. The Forest Service estimates that the die-off from white-nose syndrome means that at least 2.4 million pounds of bugs (1.1 million kg) will go uneaten and become a financial burden to farmers. The disease may also threaten an already-endangered species, such as the big-eared bat (Corynorhinus townsendii virginianus), the official state bat of Virginia. Some bat species are adapting to slow the spread of the disease by roosting alone more frequently.
Comparisons have been raised to colony collapse disorder, another poorly-understood phenomenon resulting in the abrupt disappearance of Western honey bee colonies, and with chytridiomycosis, a fungal skin disease linked with worldwide declines in amphibian populations.
Biologists are investigating the geographic extent of the outbreaks and collecting samples of affected bats. Bucknell University professor DeeAnn Reeder, one of the foremost experts on White-Nose Syndrome, expects it will continue to spread across the United States, and drive some species to extinction. "While a number of researchers from multiple academic disciplines are now working on WNS research, and while we are beginning to understand how this fungus (Geomyces destructans) is killing bats, we are really struggling in our attempts to control the spread," Reeder said. A geographic database is being developed to track the location of sites where WNS has been found, collecting information at each site in regards to the number of bats affected.
The U.S. Fish and Wildlife Service is also partnering with the Northeastern Cave Conservancy to track movements of cavers that have visited affected sites in New York. It has also advised closing caves to explorers in 20 states, from the Midwest to New England. This directive will soon be extended to 13 southern states. As one Virginia scientist stated, "If it gets into caves more to our south, in places like Tennessee, Kentucky, Georgia and Alabama, we’re going to be talking deaths in the millions.". In March 2012, WNS was discovered on some tri-color bats (Perimyotis subflavus) in Russell Cave in Jackson County Alabama.
Recent research has found that the fungus may respond to typical human anti-fungal treatments. More studies are being undertaken to determine how best to use this knowledge.
Increasing evidence is accumulating that points to Geomyces destructans as the sole cause of the disease. A 2008 study determined that the fungus found on the muzzles, wings, ears and all exposed skin tissues of infected bats is a member of the genus Geomyces. A 2011 study found that 100% of healthy bats infected with the fungus Geomyces destructans cultured from infected bats exhibit lesions consistent with the disease, providing evidence that the fungus alone, and not a combination of factors is responsible for the disease.
There is consensus among researchers that bat-to-bat transmission is the predominant factor in the spread of the disease. A laboratory experiment suggests that physical bat-to-bat contact is required for the spread of the disease. The same study found that bats in mesh cages adjacent to infected bats did not contract the fungus, implying that the fungus is not airborne, or at least is not spread from bat to bat through the air.
The role of humans in the spread of the disease, and the transmission of the fungus from Europe, is debated. The occurrence of the same fungus in healthy bats in Europe suggests that the fungus originated in Europe, where some bats acquired immunity and was somehow transmitted to bats in North America which lack immunity to the disease. This aspect of the geographic spread led some officials to argue that humans may also transmit WNS from infected sites to clean sites, probably on clothing and equipment.
The fungus Geomyces destructans, or a closely related species of fungus, has been found in soil samples from infected caves and suggests that it can be transported from cave to cave by soil, such as that carried by human clothing. Precautionary decontamination methods are being encouraged to inhibit the possible spread of spores by humans. Cave management and preservation organizations have been requesting that cave visitors limit their activities and disinfect clothing and equipment that has been used in possibly infected caves. In some cases, access to caves is being closed entirely.
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- "Newly Identified Fungus Implicated In White-nose Syndrome". Science Daily. 2008-10-31. Retrieved 2009-10-25.
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- National Geographic: "Deadly Bat Disease Linked to Cold-Loving Fungus". Retrieved 2008-11-02.
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- "Culprit behind bat scourge confirmed" Nature
- Bureau of Land Management FAQ
- Linder, Daniel; Blehert (2011-03-18). "DNA-based detection of the fungal pathogen Geomyces destructans in soils from bat hibernacula". Mycologia 103 (2): 241–246. PMID 20952799.
- "Something is killing our bats: The white-nose syndrome mystery". U.S. Fish and Wildlife Service. Retrieved 2008-02-14.
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- Species Profile- White-Nose Syndrome, National Invasive Species Information Center, United States National Agricultural Library. Lists general information and resources for White-Nose Syndrome.
- White-nose Syndrome from the U.S. Fish and Wildlife Service Northeast Region (public domain photos and Flickr page)
- White Nose Syndrome: The mystery fungus killing our bats, a comprehensive article from Wild Things Sanctuary
- White-Nose Syndrome Threatens the Survival of Hibernating Bats in North America from the U.S. Geological Survey Fort Collins Science Center
- Testimony before the U.S. House Committee on Natural Resources on June 4, 2009
- WNS News from the National Speleological Society
- WNS News Archive from Bat Conservation International
- Bat Man vs. White Nose article and video from BU Today, Sept 10, 2009
- White Nose Syndrome narrated slideshow from wildlife photographer Gerrit Vyn
- Bat Boy joins fight against WNS humor from Weekly World News
- http://savelucythebat.org/ Empowering youth to conserve North American bats in the face of WNS and other threats
- Scientific community unites to save bats - article and video from WHYY/NewsWorks