Experts tackle the devil's tumour

Over the past decade, tens of thousands of Tasmanian devils have been killed by Devil Facial Tumour Disease.

The diseased animals develop facial tumours, which can grow so large that they prevent feeding.

Scientists fear the devils - which are a symbol for Tasmania - could become extinct if action is not taken.

Tasmania's other famous animal, the thylacine or Tasmanian tiger, died out in the 1930s.

Dramatic decline

Hamish McCallum, professor of wildlife research at the University of Tasmania's School of Zoology, said the disease is having a devastating effect on the devils.

"In all the populations that have been infected, they've declined dramatically - often by up to 90% - and they continue to decline," he told the BBC's World Today.

"I think there is a substantial risk that unless we do something, the populations may be extinct over a time frame of 10 to 15 years - or may be even shorter than that."

But he said the Tasmanian people were "quite determined" not to let their largest surviving marsupial carnivore die out.

The disease has struck 57 separate locations in Tasmania since December 1996.

Environmental authorities have recently taken four colonies of healthy animals off the island and placed them in zoos on the mainland.

The cause of the disease is not known, but scientists believe it is spread through contact with other animals, mostly by biting.

Grotesque sight

Tasmanian devils have powerful jaws that are able to crunch through the bones of much larger animals. They are known to bite each other's faces during fights and courtship behaviour.

A severely diseased devil is a grotesque sight, with large tumours protruding from the face and neck, sometimes pushing out teeth and invading eye sockets.

As the tumours interfere with feeding, the animals become emaciated and usually die within six months of showing lesions.

The suspected means of transmission is highly unusual. Scientists believe that when one animal attacks another, it leaves cancerous cells behind in the bite.

There is a dog cancer which is also thought to be transmitted this way, but the canine immune system is apparently able to deal with the malignant cells.

The authors of a report from last year suggested that close kinship and low genetic diversity among Tasmanian devils reduces their immune response to transplanted cancer cells, making it more likely that they will take hold.

There is no evidence that the disease has spread to other animals.

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