In 2018, I included the Tasmanian devil in a blog about animals and cancer. At the time, the species was being pushed to extinction by a contagious cancer called the devil facial tumor (DFTD).
DFTD spreads from devil to devil through bite injuries. Because Tasmanian devils are a top predator, a reduction in their population can disrupt the ecosystem and threaten other Tasmanian species. Given ongoing research, I thought it was time to follow up on this story to highlight what scientists have learned about this unusual disease.
A Rare Form of Transmissible Cancer
When cancer specialists looked at DFTD tumors from multiple devils, they found that the cancer cells were genetically identical. This discovery led to a remarkable conclusion: the cancer itself is contagious, spreading from devil to devil through the creatures’ aggressive biting behavior during mating.
There are only two other examples of contagious tumors in animals. In both cases, the cancer cells are also genetically identical across individuals.
Dogs can develop transmissible venereal tumors (CTVT) and spread it to other dogs during mating behaviors. This cancer originated in wolves and has been affecting dogs for millennia.
The third contagious animal cancer is a form of leukemia in clams, spread through sea water.
Three-Pronged Approach to Controlling Devil Facial Tumor
Scientists have used three approaches to managing DFTD:
Understanding the disease: research has shown that both tumor genetic mutations and low genetic diversity in Tasmanian devils contribute to the spread of DFTD.
Protecting the species: conservation efforts aim to preserve the species and maintain its ecological role in Tasmania.
Strengthening populations: programs focus on increasing the population of disease-free devils in the wild and improving genetic diversity.
Tasmanian Devil Insurance Program
While the “Tasmanian Devil Insurance Program” sounds like insurance you’d purchase to protect yourself from Taz, the Looney Tunes Tasmanian devil, this program is a serious conservation strategy to prevent devils from becoming extinct.
Healthy devils from areas not affected by DFTD, as well as orphans from mothers that succumbed to DFTD, have been safely housed in zoos around the world. This “insurance population” has grown to more than 600 individuals.
To further safeguard the species, some devils have been relocated to a disease-free island. Periodically, additional devils are introduced to maintain genetic diversity.
Hope for the Future
Initial predictions indicated Tasmanian devils would be extinct by 2042. Fortunately, it seems like efforts to protect the species have prevailed. Experts now predict the population will stabilize in 2030.
However, despite these efforts, the Tasmanian devil population has not sufficiently recovered to be removed from the endangered species list. In addition to DFTD, devils face ongoing threats from habitat destruction and automobile injuries.
On the bright side, the lessons learned in saving the Tasmanian devil have stretched beyond Tasmania. Insights from this work are helping scientists address other wildlife diseases, including the global pandemic of chytrid fungus in frogs and white-nose syndrome in bats.