Melioidosis: A hidden tropical disease in Sri Lanka

ABSTRACT

Melioidosis, caused by the soil saprophyte Burkholderia pseudomallei, is found in tropical countries. Infection is acquired from soil and water by inoculation through the skin and mucous membranes, inhalation into the respiratory tract and ingestion of untreated water. Clinical manifestations range from acute fulminant septicaemia to chronic localized infection characterised by abscess formation. Isolation of Burkholderia pseudomallei from patient specimens confirms the diagnosis. Although exposure is widespread in rural, agricultural communities, clinical disease is less common as it usually requires compromised immunity, commonly diabetes. Case fatality is high in the absence of effective antibiotic treatment which comprises an acute phase of intravenous antibiotics and a long eradication phase of oral antibiotics. Prevention and control is difficult as the bacterium is widespread in the soil and water of endemic countries and exposure is common in rural, agricultural populations. Sri Lanka was not considered a country with endemic melioidosis in the past. National surveillance was instituted in 2006. Around 450 culture positive cases and more than 1 000 antibody positive cases were recorded to date. Males predominated. The age range was wide. All provinces were affected with the majority living in rural areas. Case load increased during the two monsoons. There was representation of all population groups including farmers, drivers, housewives, school children, professionals, businesspersons, white collar and blue collar workers. Diabetes was the predominant risk. Clinical presentations included community acquired sepsis and pneumonia, superficial and deep abscesses, septic arthritis, neurological melioidosis and endocarditis. Mortality was more than 20%. Melioidosis is endemic in Sri Lanka with a wide geographic and demographic distribution. There is a need to extend surveillance to under-resourced parts of the country.