Impact of single round of indoor residual spray with lambda-cyhalotrin 10% WP on Plasmodium falciparum infection in Akola district, Maharashtra State.

Lambda-cyhalothrin 10% WP (ICON 10WP) was sprayed from 5th November 1997 at a dose of 25 mg/m2 as indoor residual spray in 74 high risk villages. The spray was completed within 10 days in most of the villages. The monthly entomological monitoring showed nil density of Anopheles culicifacies and Aedes and very low density of non-vector Anopheles and Culex. The impact of Lambda-cyhalothrin spray was discernible right in the month of November 1997 showing 52% reduction in P. falciparum cases as compared to the same month of preceding year. The reduction of P. falciparum cases in three months post-spray period was 77% (from 47 cases to 11 cases) as compared to similar months of preceding year and overall reduction of total malaria cases was 50% during the same period. Since the major part of transmission of P. vivax infection was over by the time Lambda-cyhalothrin spray was taken up, obviously the impact on P. vivax infection was not markedly high as compared to P. falciparum infection. Neither cerebral malaria cases nor deaths due to malaria were recorded in the sprayed villages.