Study: Biting spread devil tumors

SYDNEY, Australia (AP) -- Australian researchers have made a breakthrough discovery in understanding a rapidly spreading facial cancer that has decimated the country's Tasmanian Devil population.

A lack of genetic diversity in the fierce, fox-like creatures has meant the animals' immune system does not try to fight off the disease, spread through biting, according to a study by the University of Sydney's School of Veterinary Science released last week.

The grotesque facial tumors were first spotted in the devil population around a decade ago in the northeast of Australia's island state of Tasmania, where 90 percent of the species has died of the disease.

The affliction is spreading south and west, and scientists estimate that within five years, there will be no disease-free population in Tasmania -- the only place in the world where the carnivorous marsupials exist outside zoos.

Seeking to understand how a facial cancer could be contagious, the University of Sydney researchers found that the tumors had originated from a single cell line that was spread through the population by biting.

Because Tasmanian devils are genetically similar, their bodies do not recognize the tumors as foreign cells and do not produce an effective immune response.

"We propose that this tumor arose in a single individual and has spread through the population by biting during fights for food and mates," lead researcher Katherine Belov said in a statement.

"Essentially, there are no natural barriers to the spread of the disease, so affected individuals must be removed from populations to stop disease transmission," she said.

Scientists estimate that the wild devil population has fallen from around 140,000 in the 1990s to 80,000 in 2006 due to the spread of the tumors. By making it difficult for the animals to bite and catch prey, the tumors usually lead to their death from starvation within six months.

Experts fear the remaining healthy animals could become extinct within the next two decades if they are not isolated from the disease.

Since the disease first emerged, scientists have been working to save the endangered marsupials, known for their powerful jaws and bloodcurdling growl. Programs to try to save them include plans to relocate breeding pairs to island sanctuaries. E-mail to a friend

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