What is Melioidosis?

Melioidosis is an infectious disease caused by a species of bacteria named Burkholderia pseudomallei. Also known as Nightcliff gardener’s disease and Whitmore’s disease, the disease can be found mainly in Southeast Asia and other tropical locations. The normal habitat of Burkholderia pseudomallei is water and soil, and the infection can spread to humans who drink contaminated water or come into contact with contaminated soil.

The disease-causing bacterium is endemic in Southeast Asia, meaning that it is always present in the population. It is also common in the South Pacific, the Middle East, India, and Africa. Melioidosis is primarily a disease of the tropics, however it is considered to be of concern to the Western world due to its potential as a biological warfare agent.

Animals such as cattle, horses, pigs, sheep, goats, cats, and dogs, can also be infected with and transmit the disease. As with humans, infection occurs as a result of direct contact with contaminated sources. Direct transmission between humans is extremely rare, but may occur during sexual contact or other intimate contact if body fluids are exchanged.

Symptoms of melioidosis can fall into one of four different symptom patterns. The first is an acute localized infection, which is the result of infection that begins as a skin lesion. Early symptoms include muscle aches and fever. While these symptoms are not serious in themselves, this form of the infection can rapidly progress to infect the bloodstream, which is potentially fatal.

An acute bloodstream infection produces symptoms such as headache, respiratory difficulty, muscle aches and tenderness, diarrhea, and confusion. This form of the disease occurs most often in people who have suppressed immune systems. People with AIDS, diabetes, and renal failure, are particularly vulnerable.

When disease is due to inhalation of Burkholderia pseudomallei, a pulmonary infection such as bronchitis or pneumonia is usually the result. Possible symptoms include headache, high fever, muscle aches, chest pain, and a cough. The fourth form of infection is called a chronic suppurative infection. This involves one or more organs, which may include the skin, liver, lung, spleen, bones, brain, and lymph nodes.

In order for melioidosis to be diagnosed, Burkholderia pseudomallei must be isolated and cultured from a body fluid or tissue sample taken from the patient. Samples such as stool, urine, or blood are normally used for this purpose. Another method of diagnosis is the measurement of antibodies specific for the bacteria. Detection of such antibodies indicates the patient has been in contact with the bacteria, but not necessarily that they have an active infection.

Melioidosis treatment typically consists of penicillin or penicillin-analog antibiotics. Several different drugs may be used, including penicillin, amoxicillin, doxycycline, cetriaxone, and aztreonam. Most types of infection are not fatal and respond well to antibiotic treatment; however acute bloodstream infection is a serious condition which is often fatal.