Abstract
BackgroundMosquitoes belonging to Anopheles gambiae species complex are the main malaria vector in Mauritania but data on their vector capacities, feeding habits and insecticide susceptibility are still scanty. The objectives of this study were to fill this gap.MethodsAdult Anopheles spp. mosquitoes were collected using pyrethrum spray catch method from two ecological zones of Mauritania: Nouakchott (Saharan zone) and Hodh Elgharbi region (Sahelian zone). Circumsporozoite proteins (CSP) for P. falciparum, P. vivax VK210 and P. vivax VK247 were detected by enzyme-linked immunosorbent assay (ELISA) from the female anopheline mosquitoes. To confirm CSP-ELISA results, polymerase chain reaction (PCR) was also performed. Blood meal identification was performed in all engorged females by partial sequencing of the mitochondrial cytochrome b gene. Molecular assessments of pyrethroid knockdown resistance (kdr) and insensitive acetylcholinesterase resistance (ace-1) were conducted.ResultsIn Nouakchott, the only species of Anopheles identified during the survey was Anopheles arabiensis (356 specimens). In Hodh Elgharbi, 1016 specimens of Anopheles were collected, including 578 (56.9 %) Anopheles rufipes, 410 (40.35 %) An. arabiensis, 20 (1.96 %) An. gambiae, 5 (0.5 %) An. pharoensis and 3 (0.3 %) An. funestus. Three of 186 female An. arabiensis collected in Nouakchott and tested by ELISA were found positive for Plasmodium vivax VK210, corresponding to a sporozoite rate of 1.6 %; however PCR confirmed infection by P. vivax sporozoite in only one of these. In Hodh Elgharbi, no mosquito was found positive for Plasmodium spp. infection. There was a statistically significant difference in the percentage of human blood-fed Anopheles spp. between Nouakchott (58.7 %, 47 of 80 blood-engorged An. arabiensis females) and Hodh Elgharbi (11.1 %, 2 of 18 blood-engorged mosquitoes). Analysis of the kdr polymorphisms showed 48.2 % (70/145) of East African kdr mutation (L1014S) in Nouakchott compared to 10 % (4/40) in Hodh Elgharbi region (P < 0.001). Nevertheless, West African kdr mutation (L1014F) was found only in An. gambiae populations (4/40, 10 %) from Hodh Elgharbi region. No ace-1 mutation was found in mosquito specimens from the two study zones.ConclusionsOverall, this study confirmed the autochthonous P. vivax malaria transmission in Nouakchott, involving An. arabiensis as the main vector. It also described for the first time the absence of ace-1 mutation, the co-occurrence of both West and East African kdr mutation in An. gambiae in Mauritania, and highlighted the regional variations in the prevalence and type of kdr mutations.
Highlights
Mosquitoes belonging to Anopheles gambiae species complex are the main malaria vector in Mauritania but data on their vector capacities, feeding habits and insecticide susceptibility are still scanty
Overall, this study confirmed the autochthonous P. vivax malaria transmission in Nouakchott, involving An. arabiensis as the main vector. It described for the first time the absence of ace-1 mutation, the co-occurrence of both West and East African kdr mutation in An. gambiae in Mauritania, and highlighted the regional variations in the prevalence and type of kdr mutations
Study areas The study was conducted at five sites in Mauritania: Teyarett (18°07′40′′N, 15°56′21′′W, altitude 4.3 m), Dar Naim (18°06′14′′N, 15°55′43′′W, altitude 2 m) and Sebkha (18°04′27′′N, 16°00′16′′W, altitude 3 m) districts in Nouakchott, the capital city of Mauritania, located in the Saharan part of the country, and Kobeni (15°49′02′′N, 9°22′55′′W, altitude 198 m) and Tintane (16°18′43′′N, 10°10′01′′W, altitude 169 m) districts in Hodh Elgharbi region situated in the Sahelian part of the country (Fig. 1) [13]
Summary
Mosquitoes belonging to Anopheles gambiae species complex are the main malaria vector in Mauritania but data on their vector capacities, feeding habits and insecticide susceptibility are still scanty. Mauritania (15°–27°N, 5°–17°W) covers three ecological zones. The Saharan zone in the north where rainfall is scarce (< 100 mm annually) covers two-thirds of the surface area of the country. The Sahelian zone, characterised by an annual rainfall of 100–300 mm, extends through much of the southern and the southeastern parts of the country. The Sahel-Sudanese zone, located in the southernmost part of the country with an annual rainfall of 300–400 mm, includes Guidimagha and part of the Gorgol regions. All ecological zones support the presence of mosquitoes, including malaria vectors (Anopheles spp.). There is a lack of epidemiological data in the Sahel-Sudanese zone, and the situation of malaria in this area is possibly different from other parts of the country
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