What is Melioidosis?
Melioidosis is a neglected tropical disease caused by Burkholderia pseudomallei, an environmental bacterium found in soil and water in tropical and subtropical regions. It spreads to people and animals through contact with contaminated soil, water, or air. People can become infected by breathing in contaminated dust or water droplets, consuming contaminated food or water, or through contaminated soil entering the body through cuts, abrasions, or other breaks in the skin.
Burkholderia pseudomallei is most commonly found in tropical climates, particularly in Southeast Asia and northern Australia. Within Australia, it is found in the Top End of the Northern Territory, North Queensland, and the Kimberley region of Western Australia, and has also been identified as far south as south western Western Australia and the Brisbane River Valley. For Australian travellers, the greatest risk of exposure comes from visiting endemic regions of Southeast Asia, particularly Thailand, Malaysia, Vietnam, Cambodia, and Indonesia, where the bacteria are widespread in the environment. Cases may increase after heavy rain, cyclones, or other major weather events, as the bacteria rise to the surface of the soil.
Melioidosis can affect otherwise healthy people, but certain medical conditions significantly increase the risk of serious illness, including diabetes, heavy alcohol use, liver disease, kidney disease, chronic lung disease, and conditions that affect the immune system.
FAQs
Where is melioidosis found?
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Melioidosis occurs in tropical and subtropical regions around the world but is most commonly reported in Southeast Asia and northern Australia. Countries where the disease is considered endemic include Thailand, Malaysia, Singapore, Vietnam, Cambodia, Laos, Myanmar, Indonesia, and parts of Papua New Guinea. In Australia, most cases occur in the Northern Territory and northern Queensland. The bacteria live naturally in soil and surface water and are more likely to be encountered during the wet season or after heavy rainfall and flooding.
How does melioidosis spread?
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People usually become infected through direct contact with contaminated soil or water. The bacteria can enter the body through cuts or abrasions in the skin, by inhaling contaminated dust or water droplets, or less commonly by consuming contaminated water. Activities such as walking barefoot in muddy areas, gardening, farming, construction work, or exposure to floodwater can increase the risk of infection in endemic regions.
Could I have melioidosis and not realise it straight away?
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Yes. Symptoms most commonly develop within one to three weeks of exposure, but in some cases they can appear months later. A person may be exposed during travel, remain completely well, and then develop illness long after returning home. Because symptoms can mimic many other infections, melioidosis may not be recognised immediately unless a doctor is aware of your travel history and considers the diagnosis.
What should I do if I think I might have melioidosis?
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Seek medical attention promptly, particularly if you develop fever, cough, skin ulcers, abscesses, chest pain, shortness of breath, or flu like symptoms after travelling to a region where melioidosis occurs. Make sure you tell your doctor exactly where and when you travelled, as this information can be critical in reaching the correct diagnosis. Early treatment significantly improves outcomes, while delays can allow the infection to spread and become life-threatening.
What to Know
Melioidosis symptoms
The symptoms of melioidosis vary widely depending on which part of the body is affected, which is one reason the condition is so often mistaken for something else.
The most common form affects the lungs. A pulmonary infection may cause cough, chest pain, high fever, headache, and loss of appetite, and can range from a mild respiratory illness to severe pneumonia with septicaemia. In some parts of northern Australia, melioidosis is the leading cause of fatal community-acquired pneumonia.
A localised infection is sometimes the initial presentation, usually appearing as a skin ulcer, abscess, or swollen and painful area on the body. These lesions may appear mild at first and can be easily dismissed as a minor wound infection. There may also be fever, swelling, and muscle aches alongside a visible skin sore.
In more severe cases, the infection spreads through the bloodstream, affecting multiple organs. Symptoms of a disseminated or bloodstream infection include fever, headache, difficulty breathing, stomach or chest pain, muscle pain, confusion, and seizure. The liver, spleen, kidneys, joints, bones, lymph nodes, and brain can all be involved. This form can deteriorate very rapidly and can be fatal.
Symptoms usually appear within one to 21 days of exposure, though incubation can sometimes extend to months, and rapid progression is common in severe cases, making early recognition and intervention crucial.
Melioidosis diagnosis and treatment
Diagnosing melioidosis can be challenging because its symptoms overlap with many other conditions, including pneumonia, tuberculosis, and generalised sepsis. Diagnosis depends heavily on the clinical microbiology laboratory for culture. Burkholderia pseudomallei can be cultured from blood, sputum, and other clinical samples.
Telling your doctor clearly that you have travelled to a region where melioidosis occurs is critical because it helps them know to specifically test for and consider this organism. Blood tests, chest X-ray, and imaging of internal organs may also be needed to assess how the infection has spread.
Treatment consists of an initial intensive phase followed by an eradication phase. Recommended antibiotic treatment for severe infection involves several weeks of intravenous antibiotics, followed by up to 20 weeks of oral antibiotics. If antibiotics are not taken for the full prescribed duration, early relapse can occur, usually within one to two years. Completing the full course of treatment is essential, and can span for several months.
Melioidosis prevention
There is currently no approved vaccine against melioidosis. Protection relies entirely on reducing exposure to contaminated environments and being aware of your personal risk factors.
If you have open skin wounds, or if you have a chronic condition such as diabetes or kidney disease, avoid contact with soil and standing water in endemic regions. This is particularly important during and after heavy rain, cyclones, or flooding, when bacterial concentrations in surface soil and water are higher. If your work or activities involve potential exposure, wearing boots can help prevent infection through the feet and lower legs. Avoid walking barefoot or wearing open footwear such as thongs or sandals in muddy or wet environments in endemic areas.
Drink only bottled or treated water in regions where melioidosis is present, as the bacteria can be found in unchlorinated bore water and untreated water sources. If you sustain any wound or cut during travel in an endemic area, clean it thoroughly and promptly with clean water and soap, and seek medical attention if the wound is deep, dirty, or slow to heal.
After returning from an endemic region, stay alert to any unexplained fever, cough, skin sores, or flu-like illness, even weeks after your return. If any of these develop, see a doctor promptly and make sure to mention where you have travelled. Early treatment dramatically improves outcomes.