Impact of full coverage of population with Long Lasting Insecticidal Nets (LLIN) on malaria vector density in Gadchiroli district of Maharashtra

Abstract

Background & objectives: Long-lasting insecticidal nets (LLINs) are a major weapon in the fight against malaria. But protection of each of family member is not possible with current distribution system with 80% coverage. Therefore, we hypothesized that distribution of LLIN to every member of a household will be more effective at reducing vector density and ultimately malaria in endemic areas like district Gadchiroli of Maharashtra. Methods: The three sub centers Kulbhati, Pannemara and Yerkad of Murumgaon Primary Health Center of Gadchiroli district were selected for the study based on malaria incidence and LLIN distribution. Prestructured questionnaire were filled to know the distribution and use of LLIN as baseline, thereafter additional LLIN were distributed in selected villages for 100% coverage of population. Entomological surveys were undertaken to know the impact of LLIN on vector mosquito density. Results: A total of 250 houses were surveyed in these villages and questionnaires were filled regarding bednet distribution and their use. 507 LLIN were distributed in study villages (population 1270) of Murumgaon PHC. In four selected villages, additional 409 LLIN were distributed for 100% coverage of population with bed nets. Man hour density of vector mosquito in human dwelling in the experimental villages was significantly reduced, 0-19 in comparison to control (0-66). In cattle sheds, MHD of An. culicifacies was observed to be 1-243 in experimental villages vis-ΰ-vis 1-179 in control villages. During exit trap collection of mosquitoes, ~94 % mosquitoes were deterred from blood feeding. Interpretation & conclusion: In this study there was a significant impact of insecticide treated nets on vector mosquito density in human dwellings. Thus 100% coverage of human populations with LLIN may be an important tool in controlling malaria situation in endemic areas like Gadchiroli.