Second Contagious Cancer Found to Afflict Tasmanian Devils

Scientists have discovered a second type of contagious cancer that infects Tasmanian devils, two of which are shown here eating a chunk of rabbit at the Sydney's Taronga Zoo. Tim Wimborne / REUTERS

Cancer isn't usually contagious. To date, scientists had discovered only three transmissible varieties: one that afflicts dogs, another that infects soft-shell clams and a third that ravages Tasmanian devils, an endangered animal native to an island south of the Australian continent. But researchers have now identified a second contagious cancer that also infects these Aussie animals.

The first type of these, known as devil facial tumor disease (DFT1), was discovered in 1996. A decade later, scientists determined that it spreads contagiously when the animals bite each other, and it causes tumors in the mouth and face that are almost always deadly. The disease has reduced the population of Tasmanian devils by 90 percent.

In a study published December 28 in the journal Proceedings of the National Academy of Sciences, researchers wrote that they have found a second type of spreadable cancer, which they've termed DFT2. This variety is genetically distinct from DFT1 and, unlike DFT1, contains a Y chromosome, suggesting that the cancer originated in a male animal before spreading to others. So far, the researchers have found DFT2 in five animals.

"One transmissible cancer is rare," study co-author Greg Woods of Tasmania told The Scientist. "Two is astonishing."

The researchers are now working on a vaccine for DFT1. Genetic evidence suggests that both types of cancer are likely to be recognized in the same way by the Tasmanian devil's immune system, so they hope the vaccine will work on DFT2 as well.