Burkholderia pseudomallei, a saprophytic gram-negative bacillus, is the causative agent of melioidosis. The bacteria are found in soil and water, widely distributed in tropical and subtropical countries.
Through subcutaneous inoculation, ingestion, or inhalation; person-to-person transmission is extremely rare but may occur through contact with the blood or body fluids of an infected person.
Melioidosis is endemic in Southeast Asia, Papua New Guinea, much of the Indian subcontinent, southern China, Hong Kong, and Taiwan and is considered highly endemic in northeast Thailand, Malaysia, Singapore, and northern Australia. Sporadic cases have been reported among residents of or travelers to Aruba, Colombia, Costa Rica, El Salvador, Guatemala, Guadeloupe, Honduras, Martinique, Mexico, Panama, Venezuela, and many other countries in the Americas, as well as Puerto Rico. In northern Brazil, clusters of melioidosis have been reported and are associated with periods of heavy rainfall. The risk is highest for adventure travelers, ecotourists, military personnel, construction and resource extraction workers, and other people whose contact with contaminated soil or water may expose them to the bacteria; infections have been reported in people who have spent less than a week in an endemic area. Risk factors for systemic melioidosis include diabetes, excessive alcohol use, chronic renal disease, chronic lung disease (such as associated with cystic fibrosis or chronic obstructive pulmonary disease), thalassemia, and malignancy or other non-HIV-related immune suppression.
Incubation period is generally 1–21 days, although it may extend for months or years; with a high inoculum, symptoms can develop in a few hours. Melioidosis may occur as a subclinical infection, localized infection (such as cutaneous abscess), pneumonia, meningoencephalitis, sepsis, or chronic suppurative infection. The latter may mimic tuberculosis, with fever, weight loss, productive cough, and upper lobe infiltrate, with or without cavitation. More than 50% of cases present with pneumonia.
Culture of B. pseudomallei from blood, sputum, pus, urine, synovial fluid, peritoneal fluid, or pericardial fluid is diagnostic. Indirect hemagglutination assay is a widely used serologic test but is not considered confirmatory. Diagnostic assistance is available through CDC (http://www.cdc.gov/ncezid/dhcpp/bacterial_special/zoonoses_lab.html).
Ceftazidime, imipenem, or meropenem is used for initial treatment of 10–14 days, followed by 20–24 weeks of trimethoprim-sulfamethoxazole. Relapse may be seen, especially in patients who received a shorter-than-recommended course of therapy.
Travelers should use personal protective equipment such as waterproof boots and gloves to protect against contact with contaminated soil and water and thoroughly clean skin lacerations, abrasions, or burns that have been contaminated with soil or surface water.
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