Malaria transmission in a region of savanna-forest mosaic, Haut-Ogooue, Gabon

During the 2 years 1993 to 1995, an entomological survey was carried out in the savanna-forest area of Franceville, Gabon, investigating malaria trans mission in one suburban district of Franceville (Akou) and in one rural vil lage (Benguia). The biting rates of the Anopheles vectors were 10 times hig her in the rural zone compared to the suburban zone. Anopheles funestus Gil es was the predominant species in both zones followed by Anopheles gambiae s.l. Giles. The densities of Anopheles nili Theobald and Anopheles moucheti Evans were very low. In the suburban zone, transmission was maintained thr oughout the year by Art. funestus and An. gambiae s.l., whereas in rural zo nes the secondary vectors An. nili and An. moucheti were also involved in t ransmission. Humans in a suburban setting received one infective bite per p erson every 4 days, whereas in the rural area the infective biting rate was 4 times higher. Considering each vector, the observed entomological inocul ation rates (EIRs) were one infective bite per person every 6 and 17 days f or An. funestus and An. gambiae s.l., respectively, at Akou. At Benguia, th e EIRs were one infective bite per person every 2, 3. 6, and 19 days for th e 4 An. funestus, An. gambiae s.l., An. nili, and An. moucheti, respectivel y. The predominance of An. funestus over An. gambiae s.l. and its high Em m ake it the most important malaria vector in this region of Haut-Ogooue.