Abstract
Background:Reducing the burden of malaria requires better understanding of vector populations, particularly in forested regions where the incidence remains elevated. Here, we characterized malaria vectors in a locality near the Yaoundé international airport, Cameroon, including species composition, abundance,Plasmodiuminfection rate, insecticide resistance profiles and underlying resistance mechanisms.Methods:Blood-fed adult mosquitoes resting indoors were aspirated from houses in April 2019 at Elende, a village located 2 km from the Yaoundé-Nsimalen airport. Female mosquitoes were forced to lay eggs to generate F1adult progeny. Bioassays were performed to assess resistance profile to insecticides. The threshold of insecticide susceptibility was defined above 98% mortality rate and mortality rates below 90% were indicative of confirmed insecticide resistance. Furthermore, the molecular basis of resistance andPlasmodiuminfection rates were investigated.Results:Anopheles funestuss.s. was most abundant species in Elende (85%) followed byAnopheles gambiaes.s. (15%) with both having a similar sporozoite rate. Both species exhibited high levels of resistance to pyrethroids (<40% mortality).An. gambiaes.s. was also resistant to DDT (9.9% mortality) and bendiocarb (54% mortality) while susceptible to organophosphate.An. funestuss.s. was resistant to dieldrin (1% mortality), DDT (86% mortality) but susceptible to carbamates and organophosphates. The L119F-GSTe2 resistance allele (8%) and G119Sace-1 resistance allele (15%) were detected inAn. funestuss.s. andAn. gambiaes.s., respectively.Furthermore, the high pyrethroid/DDT resistances inAn. gambiaes.s. corresponded with an increase frequency of 1014Fkdrallele (95%). Transcriptional profiling of candidate cytochrome P450 genes reveals the over-expression ofCYP6P5,CYP6P9aandCYP6P9b.Conclusion:The resistance to multiple insecticide classes observed in these vector populations alongside the highPlasmodiumsporozoite rate highlights the challenges that vector control programs encounter in sustaining the regular benefits of contemporary insecticide-based control interventions in forested areas.
Highlights
Malaria is the major vector-borne disease globally and a leading public health problem[1]
The recent certification of Algeria and Argentina as malaria-free countries by the World Health Organization (WHO) has been a historic achievement for universal health coverage, and serving as a model in demonstrating the feasibility of malaria elimination in the Afro-tropical region[1]. This success was in part largely attributed to a coordinated system of vector control interventions such as long-lasting insecticidal nets (LLINs) and indoor residual spraying (IRS) among others, including prompt diagnosis, effective treatment and efficient surveillance response system[3]
In order to facilitate and reinforce the National Malaria Control Program in their efforts to implementing sustainable and efficacious vector control interventions, this study investigated the entomological component of malaria transmission in a rural setting within the forested region of Cameroon
Summary
Malaria is the major vector-borne disease globally and a leading public health problem[1]. There was a reported increase in malaria victims in 2018 compared with the previous years in ten African countries scoring the highest burden of the disease[1] To this effect, the WHO Global Technical Strategy for Malaria (2016–2030) outlines a pathway for malaria control and elimination and designates a target for a 90% reduction in global malaria mortality rates by 2030 relative to a 2015 baseline[2]. The WHO Global Technical Strategy for Malaria (2016–2030) outlines a pathway for malaria control and elimination and designates a target for a 90% reduction in global malaria mortality rates by 2030 relative to a 2015 baseline[2] In this vein, the recent certification of Algeria and Argentina as malaria-free countries by the World Health Organization (WHO) has been a historic achievement for universal health coverage, and serving as a model in demonstrating the feasibility of malaria elimination in the Afro-tropical region[1]. Any reports and responses or comments on the article can be found at the end of the article
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