Melioidosis in Southeast Asia

Abstract

After the first report of human melioidosis in Burma by Whitmore and Krishnaswami (1912), it took approximately 50 years for the establishment of its endemicity in Southeast Asian countries such as Malaysia, Singapore and Thailand. In other Southeast Asian countries, little is known about the epidemiology although melioidosis is gradually being recognized as an emerging infectious disease in Vietnam (Weber et al., 1969). The septicemic or bacteremic form is the best indicator of its presence since blood isolates generally receive greater attention for proper identification than isolates from other sites. In Thailand, the first case report appeared in 1955 (Chittivej et al., 1955). However, melioidosis was not widely recognized until the Vietnam war when the death of American soldiers due to acute pneumonitis provoked great interest in the disease (Weber et al., 1969). At that time little evidence could be found to substantiate the existence of melioidosis in Thailand. The microorganism could be isolated from soil and water collected from various parts of the country (Finkelstein et al., 1967). The prevalence of a positive serological test was found in 29% of Thai military personnel (Nigg, 1963) but strangely enough, clinical cases could not be identified. In 1975, Sompone Punyagupta and colleagues reported ten cultureproven cases of melioidosis at the meeting of the Infectious Disease Group of Thailand (Punyagupta et al., 1976). Since then clinicians and laboratory personnel in medical schools have been alert to look for the disease. The knowledge and expertise gained from a handful of cases diagnosed at medical schools was passed on to various provincial hospitals. The first national workshop on melioidosis was held 10 years later. It compiled more than 700 reported cases that led to research activities on various aspects of melioidosis. At present, 2000–3000 cases of clinical melioidosis are estimated to occur each year in Thailand with a population of 60 000 000. The incidence rate in highly endemic areas was calculated to be 3.6–5.5 cases per 100 000 population and is seasonal (Suputtamongkol et al., 1994). A multicenter study on the etiology of acute undifferentiated febrile illness from 1991 to 1992 revealed one blood isolate per 1033 cases and 11 (0.9%) cases with a positive serological test among the 1218 cases. Since there are approximately 400 000 cases of acute undifferentiated febrile illness reported to the Division of Epidemiology, Ministry of Public Health each year, 387 cases of bacteremic melioidosis and another 3612 cases with positive serology could be derived according to calculation using this information. In a laboratory survey, total numbers of the isolates were 1131 strains in 1994 and 1165 strains in 1995 (Leelarasamee et al., 1997). When the site of isolation and the annual number of isolates were plotted on a map, it was seen that Burkholderia * Tel.: +66-2-4197785. E-mail address: siall@mahidol.ac.th (A. Leelarasamee)