White nose syndrome

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A little brown bat with white nose syndrome.

White nose syndrome (WNS) is a poorly understood disease associated with the deaths of more than a million North American bats.[1] The condition, named for a distinctive fungal growth around the muzzles and on the wings of hibernating animals, was first identified in a cave in Schoharie County, New York, USA, in February 2006.[2] It steadily spread and as of spring 2010, the condition had been found in over 115 caves and mines ranging mostly throughout the Northeastern US and as far south as North Carolina and west to Tennessee and into the provinces of Quebec and Ontario in Canada.[3]

According to laboratory research in late 2011, the syndrome appears to be caused by a fungus called Geomyces destructans,[4] but no obvious treatment or means of preventing transmission is known.[5]

The US Fish & Wildlife Service (USFWS) has called for a moratorium on caving activities in the affected areas,[6] and strongly recommends that any clothing or equipment used in such areas be decontaminated after each use.

The National Speleological Society (NSS) maintains an up-to-date page to keep cavers apprised of current events and advisories.[7]

Contents

[edit] Impact

The fungus Geomyces destructans can only grow on low temperatures, in the 5 to 10 °C range (40–50°F). The fungus will not tolerate temperatures above 20 °C (68 °F), and appears to be adapted to attacking hibernating bats.[8] Infection causes bats to arouse 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 first showed up in the news after January 2007, reported in bats in some New York caves.[9] It spread to other New York caves and into Vermont, Massachusetts and Connecticut[10] in 2008.[11] In early 2009 it was confirmed in New Hampshire,[12] New Jersey, Pennsylvania,[13] West Virginia [10] and in March 2010 in Ontario, Canada, and northern Tennessee.[14][15]

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."[16] The mortality rate in some caves has exceeded 90 percent.[17][18] A once common species, little brown myotis, has suffered a major population collapse and may be at risk of rapid extinction in the northeastern US within 20 years from mortality associated with WNS.[19] There are currently 9 hibernating bat species confirmed with infection of Geomyces destructans and at least 5 of those species have suffered major mortality. Some of those species are already listed as endangered on the US endangered species list, including the Indiana bat, whose primary hibernaculum in New York has been affected.[20] 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.[17]

Bat colonies have been decimated throughout the northeastern US, 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. Furthermore, the disease could threaten an already endangered species, such as Indiana bats and the big-eared bat (Corynorhinus townsendii virginianus), the official state bat of Virginia.[21]

Comparisons have been raised to colony collapse disorder, another poorly-understood phenomenon resulting in the abrupt disappearance of Western honey bee colonies,[9][22] and with chytridiomycosis, a fungal skin disease linked with worldwide declines in amphibian populations.[23][24]

[edit] Research

Biologists are investigating the geographic extent of the outbreaks and collecting samples of affected bats.[25] 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.[25]

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.[25] 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."[21]

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.[26]

[edit] Cause

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.[23][27] 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.[4]

The fungus Geomyces destructans is a cold-loving fungus that grows at temperatures below 20 °C (68 °F) and grows on the bats when they are hibernating in caves and mines during winter.[23]

Another species of the genus is G. pannorum, a pathogen responsible for skin infections in humans.[28]

[edit] Spread

There is consensus among researchers that bat-to-bat transmission is the predominant factor in the spread of the disease.[29] A laboratory experiment suggests that physical bat-to-bat contact is required for the spread of the disease.[4] 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.[4]

The role of humans in the spread of the disease, and the transmission of the fungus from Europe, is debated.[29] 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 any immunity to the disease.[30][31] This aspect of the geographic spread lead some officials to argue that humans may also transmit WNS from infected sites to clean sites, probably on clothing and equipment.[32]

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.[33] 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.[34] In some cases, access to caves is being closed entirely.[35]

[edit] References

  1. ^ "Fish and Wildlife Service Awards $800,000 in Grants to Explore Cause, Control of White-Nose Syndrome in Bats". United States Fish and Wildlife Service. 2009-10-26. http://www.fws.gov/news/NewsReleases/showNews.cfm?newsId=9191BAAD-F8E8-0097-B3670BDF3849EBF2. Retrieved 2009-10-30. 
  2. ^ David S. Blehert et al. Bat White-Nose Syndrome: An Emerging Fungal Pathogen?. Science 9 January 2009: Vol. 323. no. 5911, p. 227 DOI: 10.1126/science.1163874
  3. ^ Bat White Nose Syndrome (WNS) by Occurrence by County/District NSS WNS Map
  4. ^ a b c d Lorch, Jeffrey M.; Meteyer, Behr, Boyles, Cryan, Hicks, Ballman, Coleman, Redell, Reeder, Blehert (2011-10-26). "Experimental infection of bats with Geomyces destructans causes white-nose syndrome". Nature advanced online publication. http://dx.doi.org/10.1038/nature10590. 
  5. ^ "Bat killer identified", New Scientist
  6. ^ http://www.caves.org/WNS/USFWS-WNS_cave_advisory_news_rls_2009-03-26_final-1.pdf
  7. ^ "White Nose Syndrome Page". National Speleological Society. http://www.caves.org/WNS/. Retrieved November 9, 2011. 
  8. ^ Cryan, Paul. "White-Nose Syndrome Threatens the Survival of Hibernating Bats in North America". USGS Fort Collins Science Center. http://www.fort.usgs.gov/wns/. Retrieved 17 December 2011. 
  9. ^ a b Hill, Michael (2008-01-30). "Bat Deaths in NY, Vt. Baffle Experts". Associated Press. http://ap.google.com/article/ALeqM5jglXh1LrwpTZZW0QjCD_H91BgVYwD8UGF9101. Retrieved 2008-02-14. 
  10. ^ a b "White Nose Syndrome; Could cave dwelling bat species become extinct in our lifetime?". Bat Conservation and Management, Inc.. http://www.batmanagement.com/wns/wns.html. Retrieved 2009-02-05. 
  11. ^ "Bat affliction found in Vermont and Massachusetts caves". Newsday.com. 2008-02-15. http://www.newsday.com/news/local/wire/newyork/ny-bc-ny--batdie-off0215feb15,0,232424.story. Retrieved 2008-02-20. 
  12. ^ http://www.nashuatelegraph.com/apps/pbcs.dll/article?AID=/20090223/NEWS02/302239991
  13. ^ Joe Kosack (2009). "WHITE-NOSE SYNDROME SURFACES IN PENNSYLVANIA". http://www.pgc.state.pa.us/pgc/cwp/view.asp?Q=175717&A=11. Retrieved 2009-02-05. [dead link]
  14. ^ Ontario Ministry of Natural Resources (2010). "White Nose Syndrome Detected In Ontario Bats". http://www.mnr.gov.on.ca/en/Newsroom/LatestNews/289824.html. Retrieved 2010-03-19. 
  15. ^ Chris Smith. "Bat in Clarksville's Dunbar Cave with deadly fungus may be migrant". The Leaf-Chronicle. http://www.theleafchronicle.com/apps/pbcs.dll/article?AID=2010100324016. Retrieved 24 March 2010. [dead link]
  16. ^ Shapley, Dan (2008-02-05). "The Gravest Threat to Bats Ever Seen". The Daily Green. http://www.thedailygreen.com/environmental-news/latest/white-nose-syndrome-bats-47020509. Retrieved 2008-02-14. 
  17. ^ a b Daley, Beth (2008-02-07). "Die-off of bats could hurt area crops". The Boston Globe. http://www.boston.com/news/local/articles/2008/02/07/die_off_of_bats_could_hurt_area_crops/. Retrieved 2008-02-14. 
  18. ^ Kelley, Tina (2008-03-25). "Bats Perish, and No One Knows Why". The New York Times. http://www.nytimes.com/2008/03/25/science/25bats.html?_r=1&hp&oref=slogin/. Retrieved 2008-03-25. 
  19. ^ Frick et al. 2010. An emerging disease causes regional population collapse of a common North American bat species. Science 329: 679-682.
  20. ^ "Unexplained "White Nose" Disease Killing Northeast Bats". Environment News Service. 2008-01-31. http://www.ens-newswire.com/ens/jan2008/2008-01-31-094.asp. Retrieved 2008-02-14. 
  21. ^ a b "Cute but contagious" The Economist, May 21, 2009
  22. ^ Mann, Bryan (2008-02-19). "Northeast Bat Die-Off Mirrors Honeybee Collapse" (audio). All Things Considered (National Public Radio). http://www.npr.org/templates/story/story.php?storyId=19174588&ft=1&f=1001. Retrieved 2008-02-20. 
  23. ^ a b c Blehert DS, Hicks AC, Behr M, et al. (October 2008). "Bat White-Nose Syndrome: An Emerging Fungal Pathogen?". Science 323 (5911): 227. doi:10.1126/science.1163874. PMID 18974316. http://www.sciencemag.org/cgi/content/abstract/1163874. Retrieved 2008-11-02. 
  24. ^ "Newly Identified Fungus Implicated In White-nose Syndrome". Science Daily. 2008-10-31. http://www.sciencedaily.com/releases/2008/10/081030144613.htm. Retrieved 2009-10-25. 
  25. ^ a b c U.S. Fish & Wildlife Service, Northeast Region, "White-Nose Syndrome in bats: Something is killing our bats." http://www.fws.gov/northeast/white_nose.html (accessed April 14, 2009)
  26. ^ Chaturvedi, Sudha; Rajkumar, Li, Hurteau, Shtutman, Chaturvedi (2011-03-02). "Antifungal Testing and High-Throughput Screening of Compound Library against Geomyces destructans, the Etiologic Agent of Geomycosis (WNS)". PLos ONE 6 (3). http://dx.doi.org/10.1371%2Fjournal.pone.0017032. 
  27. ^ National Geographic: "Deadly Bat Disease Linked to Cold-Loving Fungus". http://news.nationalgeographic.com/news/2008/10/081031-bat-fungus.html. Retrieved 2008-11-02. 
  28. ^ Kolbert, Elizabeth, "Batless", The New Yorker; March 29, 2010, pp 42-43.
  29. ^ a b Youngbaer, Peter (2010-02-20 & 2011-04), "White-Nose Syndrome: Year Six, and Counting", NSS News, http://www.caves.org/WNS/Hellhole%20Photo%20Trip.pdf, retrieved 2011-09-01 
  30. ^ Puechmaille, Sébastien J.; Verdeyroux, Pascal; Fuller, Hubert; Ar Gouilh, Meriadeg; Bekaert, Michaël; Teeling, Emma C. (February 2010). "White-nose syndrome fungus (Geomyces destructans) in bat, France" (PDF). Emerging Infectious Diseases (Atlanta: Centers for Disease Control and Prevention) 16 (2). doi:10.3201/eid1602.091391. ISSN 1080-6059. http://www.cdc.gov/eid/content/16/2/pdfs/09-1391.pdf. Retrieved 2 January 2010. 
  31. ^ "Culprit behind bat scourge confirmed" Nature
  32. ^ Bureau of Land Management FAQ
  33. ^ 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. http://www.mycologia.org/content/103/2/241.full. 
  34. ^ "Something is killing our bats: The white-nose syndrome mystery". U.S. Fish and Wildlife Service. http://www.fws.gov/northeast/white_nose.html. Retrieved 2008-02-14. 
  35. ^ Munger, Edward, Jr. (2008-02-14). "Group asking cavers to keep out". Daily Gazette. http://www.dailygazette.com/news/2008/feb/14/0214_caves/. Retrieved 2008-02-14. 

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