Vectorial role of Anopheles subpictus Grassi and Anopheles culicifacies Giles in Angul District, Orissa, India.

Malaria transmission by Anopheles subpictus Grassi, 1899 and Anopheles culicifacies Giles, 1901 was studied from March 2004 to February 2007 in Angul District, Orissa, India, which is highly endemic for malaria. Adult mosquitoes were collected from human dwellings using sucking tubes and a mechanical aspirator. After identification, some An. subpictus and An. culicifacies specimens were subjected to a precipitin test to determine their anthropophilic index and the remaining samples were preserved in isopropyl alcohol for sporozoite detection by nested PCR. An. subpictus was the most prevalent (29.0%) anopheline species detected, followed by An. culicifacies (11.6%). The anthropophilic index for the An. subpictus was higher than An. culicifacies and was highest during the summer season. Malaria sporozoite rates of 0.52% and 1.82% were detected for An. subpictus and An. culicifacies, respectively. Sporozoites were detected during the summer in An. subpictus and during the rainy season and winter in An. culicifacies. The slide positivity rate (SPR) was high during the summer. The high anthropophilic index and presence of sporozoites in An. subpictus during the summer indicate An. subpictus is a contributory factor for the high SPR during the summer, and An. culicifacies is a contributory factor for the high SPR during the rainy and winter seasons, along with other anophelines. In the present study An. subpictus has been incriminated as a vector of malaria for the first time in Orissa.