Melioidosis is a threat to human health throughout South and South-East Asia, Northern Australia, the Indian subcontinent and areas of South America. The geographic distribution of this infection is predicated on the presence of the causative organism, Burkholderia pseudomallei, in the environment. Infection is thought to result from bacterial inoculation, ingestion or inhalation. The number of cases that occur in Thailand appears to be associated with the quantity of B. pseudomallei that can be cultured from soil. Disease incidence is generally grossly underestimated since microbiological culture is required to confirm the diagnosis and this is lacking in many of the affected areas.

Most common Type I colony morphology of B. pseudomallei on Ashdown’s agar. The colony appears irregular-edge, rough and pale purple.
Map of Ubon Ratchathani Province, Thailand, with proven melioidosis cases in green spots.

We study the epidemiology of sepsis at Sappasithiprasong hospital in Ubon Ratchathani, northeast Thailand, where the most common cause of bacterial sepsis in adults is B. pseudomallei. The annual incidence of human melioidosis in Ubon Ratchathani province is currently 21.0 per 100,000 population, up from 4.4 per 100,000 for the period 1987 to 1991. The reason for this increase is unclear but parallels a rising life expectancy and concomitant increase in people with predisposing conditions for melioidosis such as diabetes mellitus. The mortality rate from melioidosis at Sappasithiprasong hospital is 40%. The number of people dying from melioidosis in northeast Thailand is now comparable to deaths from tuberculosis, and exceeds those from malaria, diarrhoeal illnesses and measles combined, diseases considered to high priority by funding agencies and global health organizations. Important areas of future research are to define strategies to reduce mortality from melioidosis and to develop evidence-based guidelines on the prevention of infection.