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[[Image:Tasmanian Devil Facial Tumor Disease.png|thumb|Devil facial tumor disease causes tumors to form in and around the mouth, interfering with feeding and eventually leading to death by starvation.]]
[[Image:Tasmanian Devil Facial Tumour Disease.png|thumb|Devil facial tumor disease causes tumors to form in and around the mouth, interfering with feeding and eventually leading to death by starvation.]]


'''Devil facial tumor disease''' ('''DFTD''') is an aggressive non-viral transmittable [[parasitic cancer]] that affects [[Tasmanian Devil]]s. The first "official case" was described in 1996, in [[Australia]]. In the subsequent decade the disease ravaged [[Tasmania]]'s wild devils, with estimates of decline ranging from 20% to as much as a 50% of the devil population, across over 65% of the state.<ref name="dftdupdatejune20005">DPIWE. 2005. [http://www.dpiwe.tas.gov.au/inter.nsf/Attachments/LBUN-6D73V5/$FILE/Tas_devil_update_June2005.pdf Devil Facial Tumor Disease - Update June 2005]</ref><ref name="dpiwe dms2005">DPIWE. 2005. [http://www.dpiwe.tas.gov.au/inter.nsf/Attachments/LBUN-6996MH/$FILE/DFTD_DMS_Feb05a.pdf Tasmanian Devil Facial Tumor Disease, Disease Management Strategy]</ref> Affected high-density populations suffer up to 100% mortality in 12&ndash;18 months.<ref name="dpiweweb3">DPIWE. [http://www.dpiwe.tas.gov.au/inter.nsf/WebPages/LBUN-5QF86G?open Disease Affecting Tasmanian Devils]</ref> The disease has mainly been concentrated in Tasmania's eastern half.
'''Devil facial tumor disease''' ('''DFTD''') is an aggressive non-viral transmittable [[parasitic cancer]] that affects [[Tasmanian Devil]]s. The first "official case" was described in 1996, in [[Australia]]. In the subsequent decade the disease ravaged [[Tasmania]]'s wild devils, with estimates of decline ranging from 20% to as much as a 50% of the devil population, across over 65% of the state.<ref name="dftdupdatejune20005">DPIWE. 2005. [http://www.dpiwe.tas.gov.au/inter.nsf/Attachments/LBUN-6D73V5/$FILE/Tas_devil_update_June2005.pdf Devil Facial Tumor Disease - Update June 2005]</ref><ref name="dpiwe dms2005">DPIWE. 2005. [http://www.dpiwe.tas.gov.au/inter.nsf/Attachments/LBUN-6996MH/$FILE/DFTD_DMS_Feb05a.pdf Tasmanian Devil Facial Tumor Disease, Disease Management Strategy]</ref> Affected high-density populations suffer up to 100% mortality in 12&ndash;18 months.<ref name="dpiweweb3">DPIWE. [http://www.dpiwe.tas.gov.au/inter.nsf/WebPages/LBUN-5QF86G?open Disease Affecting Tasmanian Devils]</ref> The disease has mainly been concentrated in Tasmania's eastern half.

Revision as of 13:59, 12 August 2009

Devil facial tumor disease causes tumors to form in and around the mouth, interfering with feeding and eventually leading to death by starvation.

Devil facial tumor disease (DFTD) is an aggressive non-viral transmittable parasitic cancer that affects Tasmanian Devils. The first "official case" was described in 1996, in Australia. In the subsequent decade the disease ravaged Tasmania's wild devils, with estimates of decline ranging from 20% to as much as a 50% of the devil population, across over 65% of the state.[1][2] Affected high-density populations suffer up to 100% mortality in 12–18 months.[3] The disease has mainly been concentrated in Tasmania's eastern half. Visible signs of DFTD begin with lesions and lumps around the mouth. These develop into cancerous tumors that may spread from the face to the entire body. The tumors interfere with feeding, and the affected animal may starve to death.

Transmissible cancer is extremely rare. There is only one other known type - canine transmissible venereal tumor (CTVT) which is spread in dogs through sexual activity and has been known to science for about 100 years.[4][5]

Characteristics

Using cultures of the cancerous tissue to study the condition, researchers have identified the cancer as a neuroendocrine tumor, and all the cancer cells have identical chromosomal rearrangements.[6] A virus was initially thought to be the cause of DFTD, but no evidence of such a virus could be detected in the cancer cells. Environmental toxins had also been suspected.[7] However, ultimately the idea that cancer cells themselves are an infective agent turned out to be correct, with transmission of the disease occurring by biting, feeding on the same material, and aggressive mating (rough sexual intercourse). Final confirmation of this came when researcher Anne-Maree Pearse and colleagues[8] found an infected animal that had a chromosomal abnormality in its non-tumorous cells that did not appear in its tumor cells, proving that the tumor cells could not have descended from the animal's own cells.[9][10] Pearse believes that this may prove vital to the survival of the devils. Since June 2005, three females have been found that are partially resistant to DFTD.[11]

Further research from the University of Sydney has shown that the infectious facial cancer may be able to spread because of vanishingly low genetic diversity in devil immune genes (MHC class I and II).[12] The same genes are also found in the tumors, so the devil's immune system does not recognise the tumor cells as foreign.[13][14] There are at least nine strains of the cancer, showing that it is evolving, and may become more virulent.[15] The strains may also complicate attempts to develop a vaccine, and the mutation of the cancer may mean that it could spread to other related species, like the quoll.[16]

Tasmanian Devil cells have 14 chromosomes, while the tumor cells contain 13.[17] The DFTD cells have similar karyotype anomalies as cancer cells from canine transmissible venereal tumor (CTVT), a cancer of dogs that is transmitted between canines by physical contact.[6][18]

According to the Allograft Theory, devil facial-tumor disease is transmitted by bites that the animals inflict on each other. Every animal with this disease has chromosomes in their tumors that undergo identical complex rearrangements.[19]

The Tasmanian devil facial tumor is similar to the Syrian hamster tumor in that they both exhibit fast tumor growth and they result in host death. These two are examples of non-viral transmissible tumors.

Preservation response

In response to the impact of DFTD on Tasmanian Devil populations, forty-seven Devils have been shipped to mainland Australian wildlife parks to attempt to preserve the genetic diversity of the species. The Tasman peninsula is being considered as a possible "clean area" with the single narrow access point controlled by physical barriers. The Tasmanian Department of Primary Industries and Water is experimenting on culling infected animals with some signs of success.[20][21] Previously, a Devil named Cedric was thought to have a natural immunity to the disease, but he then developed two tumors on his face. These were cut out, but it cast doubt on the research that had been conducted on him.[22]

See also

References

  1. ^ DPIWE. 2005. Devil Facial Tumor Disease - Update June 2005
  2. ^ DPIWE. 2005. Tasmanian Devil Facial Tumor Disease, Disease Management Strategy
  3. ^ DPIWE. Disease Affecting Tasmanian Devils
  4. ^ Loh, Richmond. 2003. Tasmanian Devil (Sarcophilus harrisii) facial tumor (DFT). Paper prepared for the Devil Facial Tumor Disease Workshop, Sir Raymond Ferral Centre, University of Tasmania, Newnham, 14 October 2003, p. 2.
  5. ^ Experts tackle the devil's tumor, BBC News, 20 February 2007.
  6. ^ a b Bostanci, A. (2005). "A Devil of a Disease". Science. 307: 1035. doi:10.1126/science.307.5712.1035. PMID 15718445.
  7. ^ Owen, David and Pemberton, David. 2005. Tasmanian Devil: A unique and threatened animal. Crows Nest, Australia: Allen & Unwin. ISBN 1-74114-368-3
  8. ^ Pearse, A-M., Swift, K. (2006). "Allograft theory: Transmission of devil facial-tumor disease" (abstract). Nature. 439 (7076): 549. doi:10.1038/439549a. PMID 16452970.{{cite journal}}: CS1 maint: multiple names: authors list (link)
  9. ^ Tasmanian devils felled by rare cancer, New Scientist, 1 February 2006.
  10. ^ Gramlin, Carolyn: Poor Devils: Critters' fights transmit cancer, Science News, 4 February 2006.
  11. ^ Story relocated : Nature News
  12. ^ "Tasmanian devil epidemic: cause isolated?". Cosmos Magazine. 27 June2007. {{cite news}}: Check date values in: |date= (help)
  13. ^ Leung, Chee Chee: Extinction warning for Tassie devils, The Age, 4 October 2007.
  14. ^ "Scientists make progress in understanding Tasmanian devil disease". International Herald Tribune. 2007-10-09.
  15. ^ http://northerntasmania.yourguide.com.au/news/local/news/environmental-issues/disease-setback-for-tasmanian-devil-tumor-evolving-with-nine-strains-now-identified/1227014.aspx
  16. ^ New Tas devil tumor strands 'harder to vaccinate' - ABC News (Australian Broadcasting Corporation)
  17. ^ "Bites spread fatal 'devil' cancer". BBC News. 2006-02-02.
  18. ^ "Study Finds That a Type of Cancer in Dogs Is Contagious". The Washington Post. 11 August 2006. {{cite news}}: Check date values in: |date= (help); Unknown parameter |accessmonthday= ignored (help)
  19. ^ Pearse, A.M. & Swift, K. 2006. Allograft theory: Transmission of devil facial-tumor disease. Nature 439, 549
  20. ^ Scientific American, March 2007
  21. ^ Contagious cancer: the evolution of a killer, David Quammen, Harper's Magazine, April 2008.
  22. ^ BBC - Fence hope for Tasmanian Devils, retrieved 5 January 2009
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