Devil Facial Tumour Disease (DFTD) is the name given to a fatal condition in Tasmanian devils which is characterised by the appearance of obvious facial tumours.
The tumours are first noticed in and around the mouth as small lesions or lumps. These develop into large tumours around the face and neck and sometimes even in other parts of the body. Badly affected devils have many tumours throughout the body.
DFTD is extremely unusual as it is only one of a small number of recorded cancers that can spread like a contagious disease. Currently we know of transmissible cancers spreading through natural animal populations in seven species across vertebrate and invertebrate organisms and in both terrestrial and marine ecosystems. It is expected further study will likely uncover more examples.
Tasmanian devil with Devil Facial Tumour Disease
Known transmissible cancers as of March 2018
DFTD is passed from devil to devil through contact, including biting associated with copulation and fighting. The live tumour cells aren't rejected by the devil’s immune system because of the cancer’s ability to ‘hide’ from the immune system.
The identification of a second type of DFTD highlights the importance of ongoing monitoring of wild populations and disease investigations as part of assisting the ongoing survival of the Tasmanian devil in the wild.
DFTD 1 specifics:
DFTD 2 specifics:
While there are differences between the two types of cancer, both DFTD 1 and 2 are contagious and fatal. Once infected, devils usually die within a few months of the cancer becoming visible. Sometimes the tumours grow inside the mouth and can push out teeth. This makes it difficult for the devil to eat. Death results from starvation and the breakdown of body functions as a result of the cancer.
In diseased areas, nearly all sexually mature Tasmanian devils (older than two years of age) become infected and succumb to the disease. Juveniles as young as one year old can also be infected. This is resulting in populations with a very young age-structure in which females have only one breeding event, whereas they would normally have three.
Populations in which DFTD has been observed for several years have declined by up to 80% (approximate, due to low sample size in recent years). There is no evidence to date of the decline in devils stopping or the prevalence of the disease decreasing.
The monitoring team continues to assess Tasmanian devil populations as DFTD spreads. This happens systematically through our
annual monitoring project.
A second transmissible cancer in Tasmanian devils
DFT1 vs DFT2 Karyotype credit Pye et al
Metzger MJ, Goff SP (2016) A Sixth Modality of Infectious Disease: Contagious Cancer from Devils to Clams and Beyond. PLoS Pathog 12(10): e1005904. doi:10.1371/journal.ppat.1005904
Pearse AM, Swift K. Allograft theory: transmission of devil facial-tumour disease. Nature. 2006; 439
(7076):549. doi: 10.1038/439549a PMID: 16452970
Pye RJ, Pemberton D, Tovar C, Tubio JM, Dun KA, Fox S, et al. A second transmissible cancer in Tasmanian devils. Proc Natl Acad Sci U S A. 2016; 113(2):374±9. doi: 10.1073/pnas.1519691113 PMID:26711993