Chapter 23

Melioidosis

It is a paradox that war often increases medical knowledge and benefits humanity. Several decades ago melioidosis, named from the Greek words meaning "having a resemblance to glanders, a distemper of asses," was a little known disease, endemic in Southeast Asia, and thought to be almost always fatal. However, the medical evaluation of military personnel who acquired melioidosis while serving in the Vietnam conflict during the 1960s and early 1970s has given new insight into this disease, which can easily be mistaken for tuberculosis or a fungal infection. In fact, infection with the causative bacillus, Burkholderia pseudomallei, can take any one of four distinct forms: acute, subacute, subclinical, and chronic (usually extrapulmonary).

Serologic surveys suggest that significant subclinical disease exists in several endemic areas of Southeast Asia and Oceania and the actual incidence of human infection is far greater than the relatively few fulminating cases reported prior to the Vietnam war. Indeed, up to 10% of people in some endemic regions survive unrecognized infections with few if any symptoms. Radiologists may be the first to alert their colleagues to the possibility of melioidosis on chest radiographs.

Synonyms

Melioidosis. Stanton's disease. Pseudocholera. Pneumoenteritis. Rangoon beggar's disease. Whitmore's disease. The Vietnamese time bomb. Sp: Equinia muermo. Fr: Morve (maliasme). Ger: Infektionskrankheit der Einhufer durch Malleomyces mallei.

Definition

Melioidosis is an infectious disease caused by a gram negative bacillus, Burkholderia pseudomallei (until recently known as Pseudomonas pseudomallei before being reclassified).

Geographic Distribution

Fig. 23.1 Geographic distribution of melioidosis.

Melioidosis is primarily endemic in Southeast Asia and Oceania, occurring chiefly in Vietnam, Laos, Cambodia, Myanmar (Burma), Thailand, Malaysia and northern Australia (Fig. 23. 1). It has a seasonal peak during the rainy season. In northeast Thailand, the infection is responsible for nearly 20% of community-acquired septicemia. Occasional patients have been reported from India, Sri Lanka, Hong Kong, Guam, the Philippines, Indonesia and New Guinea. There have been rare case reports of human infection outside of the endemic zone of Southeast Asia and Oceania, encompassing such widely divergent areas as Panama, Mexico, Ecuador and other countries of northern South America, Turkey, Iran, Madagascar, Kenya, Central West Africa, South Africa and the United States. However, most of these have been citizens or soldiers who have returned home after traveling, living or fighting in Southeast Asia. During the prolonged Vietnam conflict, over 400 hundred French and American soldiers contracted melioidosis. Between 1965 and 1969, the attack rate among U.S. Army personnel in Vietnam was estimated at three cases per month.

Veterinary disease caused by the same bacillus, B. pseudomallei, has been reported from animals in Australia, West Africa, Madagascar and Reunion islands, the Amazon basin and Caribbean, as well as in a Paris zoo and an oceanarium in Hong Kong.