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

Abstract

Transmission characteristics of malaria were studied in Matola, a coastal suburb of Maputo, the capital City, in southern Mozambique, from November 1994 to April 1996. The local climate alternates between cool dry season (May-October) and hot rainy season (November-April) with mean annual rainfall 650-850 mm. Saltmarsh and freshwater pools provide mosquito breeding sites in Matola. Malaria prevalence reached approximately 60% among people living nearest to the main breeding sites of the vectors. Plasmodium falciparum caused 97% of malaria cases, others being P. malariae and P. ovale. Potential malaria vector mosquitoes (Diptera: Culicidae) collected at Matola during daytime indoor-resting (n = 1021) and on human bait at night (n = 5893) comprised 12% Anopheles coustani Laveran (93% biting outdoors), 46% An. funestus Giles (68% biting indoors) and 42% An. gambiae Giles sensu lato (60% biting outdoors). All 215 specimens of An. gambiae s.l. identified genetically were An. arabiensis Patton. Anopheles funestus populations remained stable throughout the year, whereas densities of the An. gambiae complex fluctuated considerably, with An. arabiensis peaking during the rainy season. No concomitant rise in malaria incidence was observed. Human landing indices 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 examined microscopically. Mean daily survival rates were 0.79 for both vector species. Estimated infective bites/person/year were 15 An. funestus and 12 An. arabiensis. Biting rates were greatest at 2100-24.00 hours for An. funestus (68% endophagic) and 21.00-03.00 hours for An. arabiensis (40% endophagic). The entomological inoculation rate (EIR) declined sharply over very short distances (50% per 90m) away from breeding-sites of the vectors. Consequently, P. falciparum prevalence among Matola residents was halved 350 m within the town. Implications for the protective effectiveness of a 'cordon sanitaire' by residual house-spraying and/or the use of insecticide-treated bednets are discussed.

Analysis of Anopheles arabiensis Blood Feeding Behavior in Southern Zambia during the Two Years after Introduction of Insecticide-Treated Bed Nets

“…Peak biting after midnight has been observed in Senegal, 9,10 Chad, 8 and Kenya. 24 However, in Mozambique 13 and Tanzania, 14 high activity levels were seen as early as 9:00 pm, and in Ethiopia peak biting was seen from 7:00 pm until 9:00 pm. 42 In Macha, An.…”

“…arabiensis is more variable its foraging behavior. Although the vector can be found feeding and resting indoors in some localities, [6][7][8][9][10][11] in other areas it is mainly exophagic [12][13][14][15] and exophilic. 12,16,17 Additionally, An.…”

Habitat Partitioning of Malaria Vectors in Nchelenge District, Zambia

“…funestus population. 3,[64][65][66][67][68][69][70][71] The longevity of An. funestus is particularly important because a higher proportion of malarial parasites can successfully develop and, combined with frequent exposure to infections still present in the local human population, can continue transmission into the wet season.…”

Prevalence of Malaria among Patients Attending Public Health Facilities in Maputo City, Mozambique

“…18 Previous reports showed that Anopheles funestus and Anopheles arabienses are the most common vectors in areas surrounding Maputo City. 19 Both species have proven to have considerable endophagic behavior, which favors the benefits of IRS and ITNs as protective measures.…”