Devil facial tumour disease

Devil facial tumour disease (DFTD) is an aggressive non-viral clonally transmissible cancer which affects Tasmanian devils, a marsupial native to the Australian island of Tasmania. The cancer manifests itself as lumps of soft and ulcerating tissue around the mouth, which may invade surrounding organs and metastasise to other parts of the body. Severe genetic abnormalities exist in cancer cells - for example, DFT2 cells are tetraploid, containing twice as much genetic material as normal cells. DFTD is most often spread by bites, when teeth come into contact with cancer cells; less important pathways of transmission are ingesting of infected carcasses and sharing of food. Adult Tasmanian devils who are otherwise the fittest are most susceptible to the disease. DFTD is estimated to have first developed in 1986. There are two currently existing strains, both appearing to be derived from Schwann cells. DFT1 is the main and older strain that infects most of the devil population. It was first described in 1996 in an animal from Mount William National Park in northeastern Tasmania. DFT2 appeared around 2011 and was first detected in 2014; all cases are limited to the area of southern Tasmania near the D'Entrecasteaux Channel. There still remain disease-free pockets in the relatively isolated south-west of the island. The disease poses a direct threat to the survival of Tasmanian devils as a species as the disease is almost universally fatal. In the two decades since the disease was first spotted, population of Devils (Sarcophilus harrisii) declined by 80% (locally exceeding 90%), as the condition spread through virtually entire Tasmania. However, by 2020 the spread has stabilised and the disease no longer appeared to be destined to exterminate all devils. The Tasmanian Government, Australian universities and zoos are engaged in efforts to curb the disease. Culling infected individuals, the policy used by state officials until 2010, brought little success. Thus the main prevention method became taking hundreds of devils into captivity and then releasing some of them into the wild.