Tasmanian Devils Showing Second Form Of Contagious Cancer
A second form of contagious cancer has been found in eight Tasmanian devils across southeastern Tasmania, according to a new study. This cancer -- similar to its other form -- causes deadly face tumors and can be spread by biting, killing infected animals within months.
Since this communicable cancer, commonly known as devil facial tumor disease (DFTD), was first discovered in 1996, it has brought the species to the brink of extinction several times -- despite captive breeding and efforts made to create an effective vaccine.
When infected, DFTD causes tumors to form in and around the Tasmanian devil's mouth, making it difficult for the animals to eat and ultimately means they die from starvation. It can be transmitted through bites, sharing food or eating infected carcasses. The two forms of this cancer are genetically distinct, researchers from the Universities of Cambridge and Tasmania report in their study.
"Until now, we've always thought that transmissible cancers arise extremely rarely in nature, but this new discovery makes us question this belief," Dr. Elizabeth Murchison, senior author of a new study from the University of Cambridge, explained in the university's news release.
Tasmanian devils (Sarcophilus harrisii) are known to bite each other quite frequently during mating and feeding, thus spreading the disease fairly rapidly. These iconic marsupial carnivores are native to the Australian island state of Tasmania. Following drastic population declines, the International Union for Conservation of Nature (IUCN) categorized the Tasmanian devil as endangered in 2008.
"The second cancer causes tumors on the face that are outwardly indistinguishable from the previously-discovered cancer," Dr. Ruth Pye, first author of the new study from the Menzies Institute for Medical Research at the University of Tasmania, added. "So far it has been detected in eight devils in the south-east of Tasmania."
Transmissible cancers -- cancers which can spread between individuals by the transfer of living cancer cells -- have also been observed in some dogs and soft shell clams, according to Discovery News.
"Previously, we thought that Tasmanian devils were extremely unlucky to have fallen victim to a single runaway cancer that emerged from one individual devil and spread through the devil population by biting," Dr. Murchison continued. "However, now that we have discovered that this has happened a second time, it makes us wonder if Tasmanian devils might be particularly vulnerable to developing this type of disease, or that transmissible cancers may not be as rare in nature as we previously thought."
Their findings, recently published in the journal Proceedings of the National Academy of Sciences, have important implications for Tasmanian devil conservation programs.
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