The epidemiology of melioidosis in Papua New Guinea

Melioidosis has only been sporadically reported in PNG and its contribution to the disease burden of Papua New Guineans has been questioned. The rural district of Balimo, located within the Aramia flood plain of the Western province, was chosen to test the hypothesis that melioidosis is under recognised in rural PNG due to a lack of clinical awareness and a poorly resourced laboratory sector. A prospective clinical screening program conducted at Balimo Health Centre revealed melioidosis as the cause of a previously recognised fatal febrile illness affecting children. The implementation of diagnosis and treatment protocols reduced the apparent case fatality rates from 100% to 45%. Although case numbers were small, features of melioidosis in this community include childhood predilection (average age 12-years), a lack of traditional co-morbidity and regional clustering. Simple methods of isolate identification were tested against gold standards of phenotypic and genotypic techniques and found to be sensitive and sustainable. An IHA serological study of 747 children demonstrated a correlation between sero-reactivity and clinical incidence. Furthermore, selective culture of 374 soil samples taken from the environment within this region revealed autochthonous B. pseudomallei from village communities demonstrated to be melioidosis endemic. Of the 191 samples taken from areas within these villages where children play, 3.7% were found to harbour the organism. DNA macro restriction analysis demonstrated clonality between clinical and environmental strains further substantiating the hypothesis that a driver of childhood predilection is behaviour typical of children which encourages exposure to B. pseudomallei from permanently saturated soil and/or water, most likely through preexisting abrasions or pernasal inoculation. A lack of genetic diversity of B. pseudomallei revealed by DNA macro restriction analysis is a feature. This may represent recent importation or the comfortable niche of environment - host cycling of this virulent saprophyte. This is in contrast to the diversity demonstrated in the analysis of the avirulent PNG derived B. thailandensis. In a geographical analysis of the Balimo region, the environmental attributes of low altitude (