FRIDAY, Dec. 11, 2020 (HealthDay News) -- The spread of a deadly disease that was pushing Tasmanian devils towards extinction appears to be slowing, researchers say.
They found that the transmissible cancer called Tasmanian devil facial tumor disease is switching from an emerging disease to an endemic one.
That means the spread of the disease is decreasing to the point that each infected devil is infecting just one or fewer other devils, according to the study.
"It is cautiously optimistic good news," said research team leader Andrew Storfer, a biologist at Washington State University.
"I think we're going to see continued survival of devils at lower numbers and densities than original population sizes, but extinction seems really unlikely even though it was predicted a decade ago," Storfer said in a school news release.
Tasmanian devils are carnivorous marsupials found only on the island state of Tasmania, off the southeastern coast of Australia. Their population numbers have fallen by 80% since devil facial tumor disease was identified in 1996. The animals spread the infection when they fight and bite one another on the face.
Although the disease is still deadly to most devils who contract it, this study confirms previous field research suggesting the illness appears to be reaching an equilibrium. That means the practice of releasing captive-bred devils into the wild should be reconsidered, according to the study authors.
"Active management may not be necessary and could actually be harmful," Storfer said. "It looks like the devil populations are naturally evolving to tolerate and possibly even resist the cancer. By introducing a whole bunch of genetically naïve individuals, they could breed with the wild individuals, basically mix up the gene pool and make it less well-adapted."
Disease-free, captive-bred animals could also increase transmission of the cancer among different groups of devils.
For their study, the researchers used a type of genetic analysis called phylodynamics. This is typically used to track viruses such as influenza and the new coronavirus that causes COVID-19.
The findings could help improve understanding of how other emerging diseases evolve in animals and humans, according to the researchers.
The results were published Dec. 10 in the journal Science.
The Tasmania Parks and Wildlife Service has more on Tasmanian devils.
SOURCE: Washington State University, news release, Dec. 10, 2020