Mattancherry urban agglomeration, a diminishing focus of lymphatic filariasis in Kerala.

Parasitological survey conducted recently in Mattancherry, Kerala showed a low prevalence of microfilariae (mf), with a mf rate of 1.81%, compared to that of 1956 when the mf rate was 14.7%. No brugian infection was encountered in the present investigation, though both bancroftian and brugian infections were reported earlier. Culex quinquefasciatus, the vector of bancroftian filariasis was the most predominant (93.3%) mosquito species, and its infection and infectivity rates were 0.76% and 0.54% respectively. Mansonioides spp., the vectors of brugian filariasis constituted only 0.2% of the total mosquitoes and with no infection. The overall reduction in the prevalence of mf cases and vector infection rates over the years is attributed to the continued activities of the National Filaria Control Programme. The disappearance of brugian filariasis could mainly be due to the drastic reduction in the Mansonioides breeding habitats, as a result of rapid urbanization coupled with improved socio economic conditions.