Epidemiology of bancroftian filariasis in a semi-urban community of Kerala State.

A community-based longitudinal study was initiated in 1983 in a semi-urban area, endemic for bancroftian filariasis to determine the incidence and prevalence, natural history and clinical pattern of filarial infection and also to study the impact of control measures on it. The base-line filariometric indices observed during the initial clinico-parasitological survey and entomological observations made during the first 12 months of this study are highlighted in this paper. 5.5 per cent of the examined population had microfilaraemia with average infestation of 8.1 per 20 cmm. The microfilaraemia found to have significant (P less than 0.001) relationship with age, but not with sex (P greater than 0.05). The filarial disease which had the prevalence of 3.6 per cent showed a significant (P less than 0.001) relationship to both age and sex. The youngest microfilaria (mf) carrier was of 2 years and with filarial swelling was of 6 years age. A significant (P less than 0.001) relationship of educational status and family size was observed with disease while it was non-significant (P greater than 0.05) with microfilaraemia. With the increase in per capita income of the individuals, a significant decrease in number of persons with microfilaraemia (P less than 0.01) as well as with disease (P less than 0.05) was noted. Culex quinquifasciatus, the vector for this infection was prevalent throughout the period of observation with highest density in September. Vector infection and infectivity rates ranged from 0 to 4.4 per cent and 0 to 2.2 per cent respectively.