Melioidosis is an infectious disease caused by a gram-negative bacterium, Burkholderia pseudomallei, found in soil and water. It is of public health importance in endemic areas, particularly in Thailand and northern Australia. It exists in acute and chronic forms. Signs and symptoms may include pain in chest, bones, or joints; cough; skin infections, lung nodules and pneumonia.
B. pseudomallei was previously classed as part of the Pseudomonas genus and until 1992, it was known as Pseudomonas pseudomallei. It is phylogenetically related closely to Burkholderia mallei which causes glanders, an infection primarily of horses, donkeys, and mules. The name melioidosis is derived from the Greek melis (μηλις) meaning “a distemper of asses” with the suffixes -oid meaning “similar to” and -osis meaning “a condition”, that is, a condition similar to glanders.
This bacteria from the soil can be inhaled and travels from the nose to the brain. Seek a doctor for an antibiotic treatment when sympoms occur: fever, cough
In the subgroup of patients where an inoculating event was noted, the mean incubation period of acute melioidosis was 9 days (range 1–21 days). Patients with latent melioidosis may be symptom-free for decades; the longest period between presumed exposure and clinical presentation is 62 years. The potential for prolonged incubation was recognized in US servicemen involved in the Vietnam War, and was referred to as the “Vietnam time-bomb”. A wide spectrum of severity exists; in chronic presentations, symptoms may last months, but fulminant infection, particularly associated with near-drowning, may present with severe symptoms over hours.
A patient with active melioidosis usually presents with fever. Pain or other symptoms may be suggestive of a clinical focus, which is found in around 75% of patients. Such symptoms include cough or pleuritic chest pain suggestive of pneumonia, bone or joint pain suggestive of osteomyelitis or septic arthritis, or cellulitis. Intra-abdominal infection (including liver and/or splenic abscesses, or prostatic abscesses) do not usually present with focal pain, and imaging of these organs using ultrasound or CT should be performed routinely. In one series of 214 patients, 27.6% had abscesses in the liver or spleen (95% confidence interval, 22.0% to 33.9%). B. pseudomallei abscesses may have a characteristic “honeycomb” or “swiss cheese” architecture (hypoechoic, multiseptate, multiloculate) on CT.
Regional variations in disease presentation are seen: parotid abscesses characteristically occur in Thai children, but this presentation has only been described once in Australia. Conversely, prostatic abscesses are found in up to 20% of Australian males, but are rarely described elsewhere. An encephalomyelitis syndrome is recognised in northern Australia.
Patients with melioidosis usually have risk factors for disease, such as diabetes, thalassemia, hazardous alcohol use, or renal disease, and frequently give a history of occupational or recreational exposure to mud or pooled surface water. However, otherwise healthy patients, including children, may also get melioidosis.