Mosquitoes fauna diversity, Plasmodium falciparum infection and insecticide resistance status in malaria vectors in a lagoon area in Southern Benin, West Africa

Abstract

Lagoon areas maintain ideal water conditions for mosquito breeding habitats and are thus environments with high risk of malaria transmission. In Benin, several administrative units, among which the Sô-Ava District, are located in lagoon areas. We conducted entomological surveys in this lagoon district from July 2014 to June 2015, in order to update existing information on biodiversity of mosquitoes, Plasmodium falciparum infection, and insecticide resistance status in malaria vectors. Our survey found that Culex quinquefasciatus and Mansonia africana were the most abundant species, and that Anopheles coluzzii represented the main malaria vector in this area, followed by Anopheles melas. Only Anopheles coluzzii was positive to Plasmudium falcimarum circum sporozoitic protein (4.2 %). An. gambiae s.l. were susceptible to chlorpyrifos-methyl and bendiocarb but resistant to all pyrethroids tested and to pyrimiphos-methyl. The average of kdr allelic frequency from July 2014 to June 2015 was 77.4% and that of ace1 gene was less than 1%. We conclude that Anopheles coluzzii is the main malaria vector in the lagoon area we studied, somewhat contrary to our expectations. However, this malaria vector was resistant to insecticides used for bed net impregnation, even if the resistance level was lower than observed in other parts of Benin.

Human biting rhythm of Anopheles gambiae s.l. and sleeping behaviour of pregnant women in a lagoon area in Southern Benin

“…The allelic frequency of kdr gene in Anopheles coluzzii reported in the present study is consistent with that reported recently in neighbouring villages [9] and was lower than 100% observed in Cotonou, a neighbouring district. As shing is the most important economic activity in the study area, there is a lower use of insecticides linked to agriculture.…”

“…[20,21]. The low Anopheles melas proportion reported in the present study was recently reported in the same district [9], and could be due to its urbanized nature which has probably led to the proliferation of breeding sites of Anopheles coluzzii at the detriment of Anopheles melas [9,20]. Since Anopheles melas is known to have a sporozoitic index signi cantly lower than that of Anopheles coluzzii [20][21][22], the relative proliferation of breeding sites of Anopheles coluzzii is a potential health concern considering malaria transmission in this area.…”

“…However, subsequent increase in malaria transmission in this area have been masked by the large scale implementation of vectors control tools (e.g. Long Lasting Insecticidal Nets) [9]. A recent study carried out in this study area showed a general high possession of bed nets by the pregnant women with more than 8 out of 10 women using it [8].…”

“…EVALMOUS study assessed the use and the effectiveness of mosquito nets by pregnant women and other members of their household in preventing malaria [8]. This study was carried out in Sô-Ava district, a lagoon area with high risk for malaria vectors proliferation [9]. Entomological surveys and questionnaire were carried out to assess malaria vectors human biting activity and the sleeping behaviour of pregnant women.…”

Co-infecção Plasmodium falciparum e Schistosoma haematobium: papel dos genes HLA não-clássicos de classe I (HLA-G, -E e -F) na suscetibilidade à malária

“…It is also known that there is an average temperature (20-25 °C) and an average humidity of 60% (Martens et al 1995), which provide an ideal development time, between 9 and 12 days, from larva to the adult Anopheles. Ecologic features of vectors are also important for the Anopheles subspecies (Mutuku et al 2006;Djenontin et al 2010;Djènontin 2015), (Djènontin 2015). The features of the domicile represent an essential link to the understanding of malaria risk.…”