Australian Broadcasting Corporation

Broadcast: 25/05/2010

Reporter: Murray McLaughlin

Melioidosis is an often fatal disease caused by bacteria common in soil in tropical climes. During the wet season it flourishes in Northern Australia and as this wet season draws to a close more than 10 people have died from the disease.

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KERRY O'BRIEN, PRESENTER: It's known as melioidosis, an often fatal disease caused by bacteria common in soil in tropical climates and it flourishes during the wet season across Northern Australia. Over the 20 years that records have been kept, more than 600 people across the Top End have been infected and 85 have died. This northern wet season is just coming to an end, but it's brought a record number of melioidosis cases, resulting in 10 deaths. The question is: why? Murray McLaughlin reports.

WAYNE MCIVOR: I'd just be throwing up and nothing was healing in my body. So I knew something was wrong, but I didn't know what.

MURRAY MCLAUGHLIN, REPORTER: Wayne McIvor was a prime candidate to be struck down by melioidosis, a disease caused by a bacterium in tropical soils. He's been an insulin-dependent diabetic all his adult life and was infected through a wound in his foot.

WAYNE MCIVOR: I was walking around my veggie garden, pulling out a few little weeds and enjoying my garden, just wearing thongs.

VICKI KRAUSE, NT CENTRE FOR DISEASE CONTROL: People with diabetes, people who overuse alcohol, people with chronic disease like lung disease, heart disease, liver disease, renal disease, people who are on medications that suppress their immune system, they all have to be very aware that they're living in an environment with this bacteria.

MURRAY MCLAUGHLIN: After many weeks of intensive antibiotic treatment, Wayne McIvor left hospital minus four toes because the disease had penetrated the bones in his feet.

WAYNE MCIVOR: There, that's it there. There's no bones in this part of the foot.

VICKI KRAUSE: It can involve any organ in your body. It can form abscesses. But the most common presentation is pneumonia.

MURRAY MCLAUGHLIN: This Top End wet season has brought a record number of cases of melioidosis. 77 cases have been reported so far, twice the average. And of those, 10 have been fatal. The weather itself has been partly to blame.

BART CURRIE, MENZIES SCHOOL OF HEALTH RESEARCH: The more severe, the intensity of the rainfall and the winds, the greater number of cases we see in humans. It's very closely and tightly linked. We've had a lot of - some pretty severe weather events with a lot of rain and a lot of wind, so that's part of it.

MURRAY MCLAUGHLIN: The rest of it is something of a puzzle to health researchers. It's been an enduring and eventful wet season up north, but not severe enough in itself to account for the alarming spike in the infections of melioidosis, especially around Darwin.

The ageing of the population might be one factor. So too might be the growth of Darwin's population.

BART CURRIE: It's a thriving city at the moment and there's a lot of new developments, new suburbs and what is known from the literature very clearly is that where you get construction happening in an area where these bacteria are present, then it can stir them up a bit and they can start to flourish a bit.

MURRAY MCLAUGHLIN: Researchers from the Menzies School of Health Researcher are mapping hotspots, where the killer bacterium occurs across the Top End.

Hundreds of soil samples are being analysed each year, especially around Darwin and its rural neighbourhood.

MARK MAYO, MELIOIDOSIS RESEARCH PROGRAM: We do find it clustered around creeks, dams, certain areas of human habitation. We do find it around there. So that's why we're looking at disturbed sites to see if humans are causing it to be more prevalent.

MURRAY MCLAUGHLIN: Melioidosis was first identified among drug users in Rangoon early last century and the bacterium which caused it likely originated from Australia's Top End.

Researchers at the Menzies School in Darwin have used molecular typing to trace its ancestry and speculate that it spread through South-East Asia from here at the time of the last Ice age, 15,000 to 40,000 years ago. Whatever its source, it's always had a role in nature.

BART CURRIE: The role is probably a symbiotic relationship with various plants to protect those plants from other invading organisms, and indeed these bacteria have a number of nasty sort of what's called virulence properties, which is why they cause such serious illness in some humans.

MURRAY MCLAUGHLIN: The virulence of the bacterium and its ability to lie dormant for a long time were identified during the Vietnam War.

VICKI KRAUSE: US vets were coming back to the US and presenting with this illness weeks or months or even years later. And it was realised that it wasn't something that was acquired in America, but that it was something that had been acquired in South-East Asia, where soldiers had been in situations where they were in muddy situations or rice fields, particularly possibly from acquiring it through cuts in their skin.

MURRAY MCLAUGHLIN: The United States now classifies the bacterium as a bio-threat organism, and in the wake of 9/11, the Department of Homeland Security is behind United States funding of research at the Menzies School in Darwin.

Here, using DNA detection technologies, scientists are close to developing a rapid test to diagnose melioidosis.

BART CURRIE: We hope that we'll be able to say definitely this is melioidosis within six hours of the patient getting to the hospital rather than having to wait for the bacteria to grow in the laboratory, which may take up to seven days to get an answer.

MURRAY MCLAUGHLIN: For many years after its first identification in Australia in 1959, melioidosis killed nearly half its victims.

Nowadays, with wider public awareness, earlier detection and better drug treatments, the percentage of deaths is in the low teens. But the discovery of a vaccine, being driven mainly by military agencies, is still a long way off.

KERRY O'BRIEN: Murray McLaughlin reporting from Darwin.