Malaria incidence and vector density in relation to climatological factors in western Doon valley (Uttaranchal)

A study on malaria incidence conducted in Sahaspur area of District Dehradun, Uttaranchal during January 1999 to December 2002 revealed considerably high infection of Plasmodium vivax. The slide positivity rate ranged between 0.08 to 4.75 with transmission from April to November. There was not a single case of Plasmodium falciparum during the study period. Among 2402 specimens of Anophelines there were 10 species of Anopheles viz., A. culicifacies Giles 1901, A. fluviatilis James 1902, A. stephensi Liston 1901, A. subpictus Grassi 1899, A. nigerrimus Giles 1899, A. maculatus Theobald 1901, A. annularis Van der Wulp 1884, A. vagus Donitz 1902, A. pulcherrimus Theobald 1902 and A. aconitus Donitz 1902. A. stephensi (15.57%) tops the rank followed by A. nigerrimus (14.19%), A. fluviatilis (13.94%), A. subpictus (13.53%), A. culicifacies (11.32%) and A. maculatus (11.11%) in succession. The climatological parameters during July to October favoured the transmission of malaria while perennial transmission of malaria was attributed to low socio-economic conditions, poor surveillance and inadequate intervention measures.