Anopheles arabiensis and An. funestus are equally important vectors of malaria in Matola coastal suburb of Maputo, southern Mozambique

Transmission characteristics of malaria were studied in Matola, a coastal s uburb of Maputo, the capital City, in southern Mozambique, from November 19 94 to April 1996. The local climate alternates between cool dry season (May -October) and hot rainy season (November-April) with mean annual rainfall 6 50-850 mm. Saltmarsh and freshwater pools provide mosquito breeding sites i n Matola. Malaria prevalence reached similar to 60% among people living nea rest to the main breeding sites of the vectors. Plasmodium falciparum cause d 97% of malaria cases, others being P. malariae and P. ovale. Potential malaria vector mosquitoes (Diptera: Culicidae) collected at Matol a during daytime indoor-resting (n = 1021) and on human bait at night (n = 5893) comprised 12% Anopheles coustani Laveran (93% biting outdoors), 46% A n. funestus Giles (68% biting indoors) and 42% An. gambiae Giles sensu lato (60% biting outdoors). All 215 specimens of An. gambiae s.l. identified ge netically were An. arabiensis Patton. Anopheles funestus populations remain ed stable throughout the year, whereas densities of the An. gambiae complex fluctuated considerably, with An. arabiensis peaking during the rainy seas on. No concomitant rise in malaria incidence was observed. Human landing in dices of An. funestus and An. arabiensis averaged 1.8 and 3.8 per man-night , respectively. Overall Plasmodium sporozoite rates were 2.42 +/- 1.24% in 2181 An. funestus and 1.11 +/- 1.25% in 1689 An. arabiensis dissected and e xamined microscopically. Mean daily survival rates were 0.79 for both vecto r species. Estimated infective bites/person/year were 15 An. funestus and 1 2 An. arabiensis. Biting rates were greatest at 2100-24.00 hours for An. fu nestus (68% endophagic) and 21.00-03.00 hours for An. arabiensis (40% endop hagic). The entomological inoculation rate (EIR) declined sharply over very short distances (50% per 90 m) away from breeding-sites of the vectors. Co nsequently, P. falciparum prevalence among Matola residents was halved 350 m within the town. Implications for the protective effectiveness of a 'cord on sanitaire' by residual house-spraying and/or the use of insecticide-trea ted bednets are discussed.