Identification of Anopheles fauna in a hyperendemic falciparum area of Orissa State, India

Abstract

Background & objective: Keonjhar district of Orissa State has been hyperendemic for falciparum malaria since many years with alarming deaths due to cerebral malaria. Therefore an entomological investigation to know more about the relative prevalence of Anopheles species was done.

Methods: Daytime indoor resting and outdoor resting, light trap and double bed net collections were made. Surveys were also made to collect Anopheles immature in streams and paddy fields. The Anopheles mosquitoes obtained by different catching methods were identified and the known vector species were subjected to gut and salivary gland dissection for vector incrimination. The infected specimens of An. fluviatilis and An. minimus were subjected to polymerase chain reaction assay for identification of sibling species.

Results: Of the anophelines collected, the most abundant was An. splendidus (18.2%) and An. fluviatilis (17.7%), followed by An. maculatus (14.0%) and An. minimus (9.0%). The sporozoite rate of An. fluviatilis and An. minimus was 0.9 and 1.4 respectively. The infected specimens have been identified as sibling species S of the An. fluviatilis complex and A of the An. minimus complex.

Interpretation & conclusion: An. fluviatilis and An. minimus are the major two species in the transmission of malaria in Keonjhar district in Orissa.