Thai research reveals simpler, safer treatment for deadly environmental - borne bacterial disease

A Thai farmer working in a rice paddy. Melioidosis prevention guidelines include avoiding direct contact with soil or ground water

Bangkok (Thailand), 28 November 2013 – Thailand based medical researchers have found that a simple oral drug regimen to cure melioidosis, a deadly tropical infection, is as effective and safer than the current drug combination used here.

Melioidosis is a little known, serious infection caused by the soil and water based bacterium Burkholderia pseudomallei. It is found in melioidosis-endemic regions of South-East Asia, the Indian subcontinent, northern Australia, parts of South America, and African countries including Niger, Gambia, Kenya and Uganda. There is currently no promising vaccine candidate for melioidosis on the horizon.

Thailand has more cases than any other country, with over 2,000 melioidosis infections a year – of which 40% are fatal. The number of people dying from melioidosis in northeast Thailand is now comparable to deaths from tuberculosis – and exceeds those from malaria, diarrheal illnesses and measles combined. Ubon Ratchathani province alone sees nearly 500 melioidosis cases a year. Patients who survive acute infection need to take oral antibiotics for 20 weeks to eradicate the bacteria and prevent relapse.

The results of the study, the largest ever undertaken on melioidosis, were published this week in the prestigious medical journal The Lancet.

The study, coordinated by the Mahidol Oxford Tropical Medicine Research Unit (MORU), drew on a nationwide network of contributors including the Thailand Melioidosis Research Network, Khon Kaen University, the Melioidosis Research Center, Khon Kaen Hospital, Sappasithiprasong Hospital in Ubon Rachathani, Udon Thani Hospital, Mahasarakham Hospital and Mahidol University.

It reveals that a simple regimen of the oral treatment for the disease - trimethoprim - sulfamethoxazole (TMP-SMX) alone - is actually as effective and has considerably fewer adverse side effects than the standard combination-drug regimen of TMP-SMX plus doxycycline now used in Thailand.

“The study is significant because it changes the oral eradicative regimen for melioidosis. The new regimen uses lower drug amounts and will reduce unnecessary side effects, thereby increasing patients’ adherence to the treatment,” said Ploenchan Chetchotisakd, Professor at Khon Kaen University, and the principal investigator for the study.

“There are times that less is more, particularly when you have to take many drugs for a long period,” said Asst Prof Direk Limmathurotsakul, Head of Microbiology at Bangkok’s MORU and a lecturer at the Faculty of Tropical Medicine, Mahidol University.

Melioidosis is preventable since infection occurs as a direct result of outdoor exposure to Burkholderia pseudomallei. Melioidosis prevention guidelines include avoiding direct contact with soil or ground water, the use of rubber boots or protective gear if contact is necessary (such as working in rice fields), drinking only bottled or boiled water, and avoiding direct contact with heavy rain and dust clouds.

“Public awareness and prevention of infection are key to reducing morbidity and mortality due to melioidosis. However, our recent survey found that 72% of Thai's have not heard of melioidosis; and that 99% of Thai's do not know how to protect themselves from infection,” said Nicholas Day, Director of MORU and Professor at the University of Oxford.

Melioidosis is often misdiagnosed because it causes a wide range of symptoms that often mimic those of other tropical diseases. The mortality rate of untreated patients can be up to 80%, and many cases die before the diagnosis is made.

“Diagnosis of melioidosis requires culture and identification of B. pseudomallei by microbiology facilities and experienced microbiologists, which are often unavailable in areas where the disease occurs. Thus, the burden of melioidosis is largely hidden in many resource limited tropical countries,” said Sharon Peacock, Visiting Professor at Mahidol University.

The Mahidol Oxford Tropical Medicine Research Unit (MORU) is a research collaboration between Mahidol University (Thailand), Oxford University (UK) and the UK’s Wellcome Trust. MORU hosts the Thailand Melioidosis Research Network website, and the Global Melioidosis Network.

MORU’s main office and laboratories are located within the Faculty of Tropical Medicine at Mahidol University in Bangkok, Thailand. MORU has study sites and collaborations across Thailand, Asia and Africa including Cambodia, Lao PDR, Myanmar, Bangladesh, India, Kenya, Democratic Republic of the Congo (DRC), Tanzania, Mozambique, Ghana, and The Gambia.