Plasmodium falciparum infection rates for some Anopheles spp. from Guinea-Bissau, West Africa

Abstract

Presence of Plasmodium falciparum circumsporozoite protein (CSP) was detected by enzyme linked immunosorbent assay (ELISA) in a sample of Anopheles gambiae s.s., A. melas and A. pharoensis collected in Guinea-Bissau during October and November 2009. The percentage of P. falciparum infected samples (10.2% overall) was comparable to earlier studies from other sites in Guinea-Bissau (9.6-12.4%). The majority of the specimens collected were identified as A . gambiae which had an individual infection rate of 12.6 % across collection sites. A small number of specimens of A. coluzzii, A. coluzzii x A. gambiae hybrids, A . melas and A . pharoensis were collected and had infection rates of 4.3%, 4.1%, 11.1% and 33.3% respectively. Despite being present in low numbers in indoor collections, the exophilic feeding behaviors of A . melas (N=18) and A . pharoensis (N=6) and high infection rates observed in this survey suggest falciparum -malaria transmission potential outside of the protection of bed nets.