What is Tasmanian devil facial tumour disease (DFTD)?
Tasmanian devil facial tumour disease (DFTD) is a transmissible cancer that affects Tasmanian devils. The disease is spread by biting and causes the appearance of tumours on the face or inside the mouth of affected Tasmanian devils. The tumours often become very large and usually cause death of affected animals. The disease has caused a massive decline in the Tasmanian devil population, and the species is now considered endangered.
In 2016 research identified a second transmissible cancer in Tasmanian devils. This second cancer, known as Devil Facial Tumour 2 (DFT2) causes tumours that are grossly indistinguishable from tumours caused by the original DFTD (that we now call DFT1).
What is the Tasmanian devil?
The Tasmanian devil is the world’s largest living carnivorous marsupial. About the size of a small dog, Tasmanian devils are well known for their piercing nocturnal shriek and their strong jaws. Tasmanian devils are found only on the island of Tasmania, to the south of the mainland of Australia. Being marsupial mammals, Tasmanian devils give birth to tiny, underdeveloped young, which complete their development in the mother’s pouch.
|Tasmanian devil young in the pouch [Photo credit: Save the Tasmanian devil Program]||
Tasmania marked in red [CC BY-SA 3.0 (http://creativecommons.org/licenses/by-sa/3.0), via Wikimedia Commons]
Where is DFTD found?
DFT1 was first observed in the 1990s in north east Tasmania. The DFTD epidemic has subsequently spread throughout most of Tasmania, and currently only areas of western and northwestern Tasmania are confirmed to have remained disease-free.
DFT2 was first observed in 2014 in the south-east of Tasmania. To date, it has only been observed in the "Channel" a peninsula in south-east Tasmania.
How is DFTD spread?
DFTD is spread by the transfer of living cancer cells by biting. Devils bite each other frequently, particularly in fights over mates and food. To our knowledge, there is no virus involved in the spread of the disease, and direct contact between devils is necessary for the disease to spread.
How old is DFTD?
DFT1 was first observed in 1996. Prior to this there was no evidence of DFTD in the devil population. DFT2 was first observed in 2014.
How does DFTD escape the immune system?
DFTD is spread by living cancer cells; thus DFTD cells should be rejected by the devils’ immune system because of its status in its hosts as a foreign graft. The mechanisms whereby DFTD escape destruction by the immune system are incompletely understood; however, down-regulation of MHC molecules from the cell surface of DFTD cells probably plays a role.
How is DFTD treated?
There is no treatment for DFTD. A number of chemotherapeutic agents have been trialled, but none have shown any efficacy in treating the disease.
What is being done to save the Tasmanian devil?
The Save the Tasmanian Devil Program is a government-funded initiative with the goal of saving the Tasmanian devil and maintaining the species as a viable member of the Tasmanian ecosystem. An insurance population has been established in order to ensure survival of the species. Research is directed towards understanding the cause, evolution and impacts of the disease with the goal of developing a vaccine, therapy or other intervention.