Voracious flesh-eater disease strikes out in tropics

A flesh-eating tropical disease that has inexplicably taken hold in Victoria has jumped north.

Victims Richard Seivers, left, and Peter Ryan. Picture: Lyndon Mechielsen

A flesh-eating tropical disease that has inexplicably taken hold in Victoria has also jumped out of its static hot zone in far north Queensland, deepening a mystery that has baffled doctors and scientists for decades.

One of the few givens of Daintree ulcer was that it had been confined to a sliver of rainforested coastline between the mouths of the Daintree and Mossman rivers north of Cairns. The voracious germ that causes it, Mycobacterial ulcerans, turns living tissue into a necrotic sludge, while suppressing the ability of the body’s immune system to fight back.

But for the first time, a cluster of infections has emerged outside the known catchment. A ­seriously affected child is among the three people confirmed in the past two years to have contracted Daintree ulcer in Julatten, atop the range on the Atherton Tablelands.

INQUIRER: Flesh-eater on the move

In Victoria, an outbreak of near-identical Bairnsdale ulcer has racked up 213 victims this year, many in Mornington Peninsula holiday towns on Melbourne’s southern doorstep. The confronting ulcers can reach down to the bone and force limbs to be amputated in severe cases.

An expert on the disease, ­microbiologist Tim Stinear of the University of Melbourne’s Peter Doherty Institute for ­Infection and Immunology, warned that the emergence of Daintree ulcer in Julatten, only 10km west of the thriving resort centre of Port Douglas, was worrying.

“I think that is significant,” Professor Stinear said. “I agree that’s a real shift … it might suggest that the (infection) reservoir has shifted. I think that’s cause for concern and definitely needs investigation.”

Tropical disease specialist John McBride, a professor of medicine with James Cook University, said the Julatten cases could not be dismissed as an ­isolated incident. “You might take the view that the first case was an anomaly, but the second and third cases make you think it is spreading,” he said.

Peter Ryan and Richard Seivers are still living with the consequences of Daintree ulcer outside the riverside village that gave its name to the disease. Mr Ryan, 70, nearly lost his right arm to a galloping infection in 1996; his longtime partner in the Daintree Tea House restaurant, Mr Seivers, 67, had an ulcer ­surgically removed from the left hip two years ago. Both were treated by Cairns surgeon Christina Steffen, who has operated on dozens of victims over two decades, including the Julatten cases. “There’s nothing you can do about it, it just comes with the territory here,” said Mr Ryan, who believes he was infected by a March fly bite.

Mr Seivers said he had no idea what caused his ulcer. “Something in there,” he said, pointing to the rainforest.

While research led by Professor Stinear and his colleague, Austin Health director of ­research Paul Johnson, shows that Bairnsdale ulcer infects ­native possums in coastal Victoria and is then spread to people by mosquitoes, the transmission path of Daintree disease remains elusive. Three of the five cases ­reported to Queensland Health so far this year emerged in the past month.

Bairnsdale disease has leapfrogged from East Gippsland to the Bellarine Peninsula on the western side of Melbourne’s Port Phillip Bay, and back across the inlet to Mornington Peninsula, posing a serious public health threat. Last year was the worst on record, with 265 cases reported.

Despite an intensive hunt for the suspected animal “reservoir” and insect vector in far north Queensland, the nearest scientists have come to identifying a culprit is a pair of positive tests for the pathogen in bandicoot droppings near the Daintree River. Few possums live in the wet tropical rainforest.

The Julatten cases have added a new layer to the mystery. The first victim in 2017 was a boy, 7, who had what Dr Steffen ­described as a “terrible” ulcer on his right leg. He recovered after antibiotic treatment and surgery.

The second, a man aged 18, ­developed an ulcer on his left calf after a camping trip to Wonga Beach, the centre of a 2011 outbreak that affected 64 people and the likely explanation for his ­exposure. But the cause of neither the boy’s infection nor that of the third patient, Glenn, 54, could be established.

Although Glenn had holidayed with the 18-year-old victim’s family at Wonga Beach in 2017, the weeping 8cm sore above his left elbow did not erupt until September last year, long after the median 4½-month incubation period for Daintree ulcer had elapsed.

Glenn, who asked that his surname not be published, said he remembered being stung by a March fly while laying down garden mulch containing local rainforest leaf mould, and this was his best guess at how he had been ­infected.

Unlike in Victoria, where unusual or novel cases of Bairnsdale ulcer are strenuously followed up by the state’s Department of Health and Human Services, he is yet to be interviewed by anyone from Queensland Health.

Dr Steffen said this was not surprising when Daintree ulcer was the poor cousin of Bairnsdale disease in terms of the resources devoted to combating and studying it. “This is far north Queensland. We are 2000km from Brisbane and the public health people are overwhelmed when they have so many things to deal with, like multi-resistant TB, dengue fever and leptospirosis. So we do this (research on Daintree ulcer) in our spare time,” she said.

Health Minister Steven Miles said he had been advised the ­Julatten patients had been interviewed by doctors treating them and the findings were reported to the World Health Organisation collaborating centre in Victoria.