BANCROFTIAN FILARIASIS - ANALYSIS OF INFECTION AND DISEASE IN 5 ENDEMIC COMMUNITIES OF NORTH-EASTERN TANZANIA

Clinical and parasitological surveys for bancroftian filariasis were c arried out in five endemic communities in north-eastern Tanzania, cove ring a population of 3086 individuals. High microfilarial (mf) prevale nces (17.7%-34.7%) and mf geometric mean intensities (251-1122 microfi lariae/ml) were observed in the communities. The mf prevalence general ly increased with age, but often levelled out in the older age groups. Larger variability was observed in individual mf intensities and no d ear association between mf geometric mean intensity and age or sex was seen. Hydrocele was the most common clinical manifestation (with a pr evalence of 30.2%-40.0% in male subjects aged greater than or equal to 20 years) followed by leg elephantiasis (with a prevalence of 2.0%-6. 8% in all subjects aged greater than or equal to 20 years). In four of the five communities, there was no significant difference in mf preva lence in males aged greater than or equal to 20 years between those wi th and without hydrocele. In all the communities, the mf geometric mea n intensities in microfilaraemic males with and without hydrocele were not significantly different. The present study therefore did not indi cate any association between hydrocele in males (the most common type of chronic clinical manifestation seen) and presence or absence of mic rofilaraemia. In contrast, only two (4.4%) of the 45 subjects with leg elephantiasis were microfilaraemic. In children aged 1-15 years, mf p revalence was significantly higher among those with microfilaraemic mo thers (18.0%) than among those with amicrofilaraemic mothers (7.9%). T he children of microfilaraemic mothers were therefore at 2.3-fold high er risk of becoming microfilaraemic than the children of amicrofilarae mic mothers. No relationship between the mf prevalence of the children and the mf status of their fathers was observed.