What Is Devil Facial Tumor Disease?
In 1996, wildlife photographer Christo Baars noticed something odd about certain Tasmanian devils he watched through his camera lens. Camped out in Mount William National Park in Tasmania, Baars spotted large, gruesome lumps around the devils' mouths and necks [source: Quammen]. His observation marked the first known sighting of Devil Facial Tumor Disease (DFTD).
DFTD, a contagious cancer introduced by feral cats, foxes and other pests, has raced across Tasmania at a swift pace, reaching more than 60 percent of the island state [source: Clausen]. In May 2008, the government officially declared the Tasmanian devil species endangered, with only 20,000 to 50,000 individuals remaining from the original 150,000. The typical lifecycle of DFTD begins with a showdown between two Tasmanian devils. If one of the animals is already infected with DFTD, a bite will deliver the virus into the other devil's healthy flesh. After that, the Tasmanian devil will develop the symptomatic facial tumors. As the tumors metastasize, they may destroy the devil's jaw and cause their teeth to deteriorate. Eventually, the animals lose their ability to eat and starve to death. This process takes place over a period of three months to a year.
Scientists have found only a handful of cancers that are contagious like DFTD. Viruses can trigger cancer, but rarely does cancer itself act as a virus, jumping among individuals. That makes not only DFTD easy to catch, but also highly fatal due to the genetic isolation among Tasmanian devils. The marsupials live in the wild only in Tasmania, which has resulted in a lack of genetic diversity among the species. In addition, the genetic sequencing of DFTD is so similar to that of a Tasmanian devil that the animal's body doesn't recognize the virus as a threat. Consequently, the animal's immune system doesn't respond to fight off the virus before it develops into full-blown cancer.
And the genetic clock ticks quickly in Tasmania. According to the Tasmanian devil preservation program, DFTD already has mutated and formed new strains. Chances are, the immune systems of Tasmanian devils won't adapt as fast to resist the emerging DFTD variations. Nevertheless, some of the animals have responded in an interesting way to the viral assassin. In communities with high disease rates, researchers recognized a pattern of earlier pregnancies. Most female Tasmanian devils breed between ages two and four; but in sickly groups, as many as 80 percent of females breed at 1 year old [source: New Scientist].
But that activity won't stamp out DFTD, which could wipe out Tasmanian devils in 20 years. Instead, the Tasmanian government and a team of scientists have stepped in to save the afflicted species.