Infectious facial tumours threaten to wipe out Tasmanian devils

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An infectious cancer is wiping out the Tasmanian devil, a marsupial carnivore whose aggressive bites could be passing facial tumours from one animal to another.

Scientists have discovered that the tumours are genetically similar, indicating that they have derived from one animal.

The tumours cause grotesque facial disfigurements which interfere with normal feeding and eventually cause the sick animals to starve to death. A wildlife photographer first documented the disease in 1996 and the cancer has contributed to the deaths of up to 80 per cent of the infected devil population in Tasmania, the only place the species is found.

Although the size of a small dog, the marsupials are known as devils because of their spine-chilling screeches, black colour and reputed bad tempers. They usually die within the first six months of being affected by the cancerous tumours.

In that time they can pass on the disease when they bite each other around the mouth during fights and aggressive mating. Scientists studied the chromosomes of cancerous cells taken from different animals and found they had all undergone an identical but complex re-arrangement that could not be due to chance alone.

In a study published in the journal Nature, researchers concluded that all the cancers were derived from a single tumour that survived when cancerous cells were transmitted in the bites of the devils. "We suggest that the devils' cancer ... is infective and that the infective agent is a rogue cell line that initially evolved in a tumour of unknown origin," said Ann-Maree Pearce, of the Tasmanian state government.

It is known that tumours can be transmitted accidentally between humans during organ transplants if the donor has cancer but this is believed to be the first case of a transmissible cancer being discovered in wild animals.

The disease seems to affect only the devils living on the eastern side of Tasmania, who appear to be genetically distinct from their cousins in the west, who may have a natural, in-built resistance to the cancer. Scientists are analysing the genetic differences between the twoto see if they can find any clues that may help to develop a vaccine or treatment for the disease.

In the meantime, conservationists are removing sick animals from wild populations in the hope that this will suppress the transmission of the tumours.

Nick Mooney, a wildlife officer for the state government, told Nature: "This work is the best hope for the devil yet. The initial results are giving us grounds for optimism."

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