Wombat researchers’ Tasmanian study develops new theory on mange mite transmission

wombat in the grass

University of Tasmania scientists spent seven years studying sarcoptic mange in bare-nosed wombats in the Central Highlands, comparing prevalence to population decline.

The disease is caused by a tiny parasitic mite that burrows into a wombat’s skin, leaving it thickened, scabbed and missing chunks of hair.

“They become so weakened that they will die, usually from just an opportunistic bacterial infection in the environment,” associate professor of wildlife ecology Scott Carver said. “It’s a really slow and horrible death that takes about three months, we think, from infection till the time that they die from it.”

Sarcoptic mange is widespread in bare-nosed wombats throughout south-east Australia, and occasionally devastates populations, such as at Narawntapu National Park, where more than 95 per cent of wombats have been wiped out.

Over the study period, the outbreak decimated more than 80 per cent of the Bronte Park population. Perhaps more significantly, about 27 per cent of wombats were infected or diseased at any one time, even as the population plummeted.

“For many infectious diseases, such as flu in humans, transmission occurs when individuals contact one another — when there are more individuals in an area, individuals contact one another more often, and transmission is more frequent,” Dr Carver said. “However, wombats are relatively solitary animals, not coming into direct contact often. “A finding of this research was that sarcoptic mange continued to spread among wombats regardless of how low the population got.”

The research indicated that mite transmission doesn’t necessarily rely on wombats coming into contact with one another, and that outbreaks are independent of population density.

Dr Carver’s research also suggested that once infection surpassed a threshold of about 25 per cent of wombats, decline was likely.

He said transmission likely came down to burrows. Wombats shift home every few days, and an infected wombat leaves behind mites, making the new tenant vulnerable to picking up the disease. “When you have relatively few burrows available per wombat, then the probability of transmission events happening among wombats is much higher than if there’s lots and lots of burrows relative to the number of wombats,” Dr Carver said.

Read more at the ABC.