Malaria vector studies in two ecological zones in southern Ghana.

Abstract

A two-year longitudinal malaria vector study was carried out in two communities, Dodowa and Prampram, located in the coastal forest and coastal savannah zones, respectively, of the Dangme West district of Ghana. <i>Anopheles gambiae s.l.</i> Giles was most prevalent in both study areas, followed by <i>An. funestus</i> Giles in Dodowa and <i>An. pharoensis</i> Theobald in Prampram. <i>Anopheles gambiae s.s.</i> occurred in sympatry with <i>An. melas</i> Theobald in Prampram. Small numbers of <i>An. nili</i> Theobald, <i>An. hancocki</i> Edwards, <i>An. coustani</i> Laveran, <i>An. moucheti</i> Evans and <i>An. hargreavesi</i> Evans were collected in Dodowa and their role in transmission was negligible. <i>Anopheles gambiae s.l.</i> and <i>An. funestus</i> were found to be the major human-biting species in Dodowa, while <i>An. gambiae s.l.</i> and <i>An. pharoensis</i> were the most common biting mosquitoes in Prampram. The overall biting rate of the anophelines at Dodowa was twice that at Prampram. <i>Anopheles gambiae s.l.</i> and <i>An. funestus</i> were identified as the main vectors of malaria by salivary gland dissections. Overall mean infectivity rate of both species was approximately 2.5 times higher at Dodowa than at Prampram. <i>Anopheles pharoensis</i> was not found to be infected with <i>Plasmodium</i> parasites. The intensity of malaria transmission at Dodowa, the coastal forest area, was about six times higher than Prampram, the coastal savanna area. Some aspects of control strategies are discussed.