Researchers working to stop a flesh-eating bacteria said they are getting closer to understanding how it spreads as several cases emerged in far north Queensland.
The Tropical Public Health Service said two notifications of Daintree ulcer were received in November – the first on November 14 involved a person living in Mossman and the second on November 24 involved a person living in the Daintree.
Both cases were most likely local from exposure, the service warned.
James Cook University Professor John McBride said the disease existed in the Daintree region but was also known to exist in Victoria and other parts of the world, including Africa.
“The ulcers get so big that you need to do major surgery, but I’ve seen people who have lost limbs as a result,” he said.
The Buruli ulcer, also known as the dreaded “Daintree ulcer” in the far north, usually starts as a pimple on the skin but if left untreated can result in the loss of limbs.
Professor McBride said researchers still had several questions about the disease but know that animals and insects were thought to spread the bacteria responsible for the condition.
“What initially appears to be a blind pimple then slowly enlarges and you form an ulcer,” he said.
“They call it Daintree ulcer in the far north and the Buruli ulcer in Africa – it gets a name from the geographical area it exists.
“It’s all caused by the bacterium Mycobacterium ulcerans. It’s a close relative of tuberculosis and leprosy.”
How common is it?
At least 33 countries with tropical, subtropical and temperate climates have reported Buruli ulcer in Africa, South America and western Pacific regions.
Professor McBride said in 2011 there were around 60 cases reported in far north Queensland, but usually there were less than half a dozen reported in the region annually.
In Australia, Buruli ulcer most commonly occurs in localised coastal areas of Victoria, but two lab confirmed cases were recorded in far north Queensland last month.
Dr Madhumati Chatterji from Tropical Public Health Services in Cairns said while theories differed, people in areas where the ulcer had been reported should take precautions.
“It is not known how the infection is contracted. There are various theories including the possibility of insect transmission,” Dr Chatterji said.
“While research is ongoing into how the infection is transmitted, people are advised to avoid contact with soil or water where possible and to avoid mosquito bites by covering the body with clothing and using insect repellent.”
How does it spread?
Professor McBride said there were many questions still surrounding the Buruli ulcer, but the disease may have been present before European settlement in Australia.
“You talk to some of the Aboriginal people and there were areas in the Daintree they traditionally avoided and we think it was because of the Daintree ulcer so we think it existed well before colonisation,” he said.
“It was first discovered by scientists in the 1930s in Australia in Bairnsdale, near Melbourne.”
Professor McBride said scientists in North Queensland, Victoria and Africa compare notes and are investigating what spreads the disease.
“The two major ideas about how people acquire Mycobacterium ulcerans, one is a theory developed in Australia is that it is a result of mosquito bites. We’ve found some evidence of wild-caught mosquitoes harbouring the microbacteria wild bacteria ulcerans,” he said.
“We’ve found that in the droppings of some bandicoots … so we think we’re probably on track trying to define how it’s transmitted.
“In Africa they have an alternative model where they’ve found the organism in water bugs and the theory there is people go wading in bodies of water and get bitten and develop bacterium after that.”
How is it treated?
Treatment usually consists of antibiotics followed by possible surgery if the ulcer does not respond to drugs.
Professor McBride said major surgery was not common but it was possible in certain cases.
“It’s mostly a painless unsightly ulcer which grows and patients go to their doctor because of a non-healing ulcer,” he said.
“The ulcers can get so big you need to do major surgery.
“It’s slowly progressive and no one would let an ulcer progress to the point where it’s life threatening.”