title: Malaria in a rural area of Sierra Leone. III. Vector ecology and disease transmission.
abstract: Studies were undertaken on the role of Anopheles gambiae and An. funestus in the transmission of malaria in four villages in a high-rainfall, forested area in the Bo district of southern Sierra Leone. Anopheles gambiae s.s., identified chromosomally as the Forest form, was the most important vector, with a mean annual sporozoite rate, based on ELISA, of 7.4%. Anopheles funestus, which was found in considerably lower numbers, was mainly a dry season vector, with an annual sporozoite rate of 11.4%. Despite these relatively high sporozoite rates, vector populations were at a low level, with approximate mean densities of only 1.0 An. gambiae and 0.1 An. funestus resting females per house room, and average biting rates of just 1.1 and 0.1 bites/person/night by these two species, respectively. In the rainy season, biting rates peaked at 9.5 An. gambiae bites/person/night and 1.0 An. funestus bites/person/night. Annual sporozoite inoculation rates by An. gambiae and An. funestus were 0.088 and 0.007 infective bites/person/night, respectively. ELISA showed that both species were highly anthropophagic. Exit-trap collections and outdoors searches showed that An. gambiae exhibited a considerable degree of exophily. Light traps inside houses caught nine anopheline species, whereas pyrethrum spray collections in houses caught only An. gambiae, An. funestus and An. hancocki.
authors.affiliation: Medical Research Council Laboratory, Bo, Sierra Leone.
authors.forename: M J
authors.initials: MJ
authors.lastname: Bockarie
authors.forename: M W
authors.initials: MW
authors.lastname: Service
authors.forename: G
authors.initials: G
authors.lastname: Barnish
authors.forename: G H
authors.initials: GH
authors.lastname: Maude
authors.forename: B M
authors.initials: BM
authors.lastname: Greenwood
mesh_terms: D000818:Animals; D000852:Anopheles / Q000145:classification / Q000502:physiology; D004463:Ecology; D005247:Feeding Behavior; D005260:Female; D006801:Humans; D007303:Insect Vectors; D008137:Longitudinal Studies; D008288:Malaria / Q000453:epidemiology / Q000635:transmission*; D012423:Rural Health; D012621:Seasons; D012807:Sierra Leone / Q000453:epidemiology