Emergence of knock-down resistance in the Anopheles gambiae complex in the Upper River Region, The Gambia, and its relationship with malaria infection in children

Abstract

BackgroundInsecticide resistance threatens malaria control in sub-Saharan Africa. Knockdown resistance to pyrethroids and organochlorines in Anopheles gambiae sensu lato (s.l.) is commonly caused by mutations in the gene encoding a voltage-gated sodium channel which is the target site for the insecticide. The study aimed to examine risk factors for knockdown resistance in An. gambiae s.l. and its relationship with malaria infection in children in rural Gambia. Point mutations at the Vgsc-1014 locus, were measured in An. gambiae s.l. during a 2-year trial. Cross-sectional surveys were conducted at the end of the transmission season to measure malaria infection in children aged 6 months–14 years.ResultsWhilst few Anopheles arabiensis and Anopheles coluzzii had Vgsc-1014 mutations, the proportion of An. gambiae sensu stricto (s.s.) mosquitoes homozygous for the Vgsc-1014F mutation increased from 64.8 to 90.9% during the study. The Vgsc-1014S or 1014F mutation was 80% higher in 2011 compared to 2010, and 27% higher in the villages with indoor residual spraying compared to those without. An increase in the proportion of An. gambiae s.l. mosquitoes with homozygous Vgsc-1014F mutations and an increase in the proportion of An. gambiae s.s. in a cluster were each associated with increased childhood malaria infection. Homozygous Vgsc-1014F mutations were, however, most common in An. gambiae s.s. and almost reached saturation during the study meaning that the two variables were colinear.ConclusionsAs a result of colinearity between homozygous Vgsc-1014F mutations and An. gambiae s.s., it was not possible to determine whether insecticide resistance or species composition increased the risk of childhood malaria infection.Electronic supplementary materialThe online version of this article (10.1186/s12936-018-2348-8) contains supplementary material, which is available to authorized users.

Effects of indoor residual spraying and outdoor larval control on Anopheles coluzzii from São Tomé and Príncipe, two islands with pre-eliminated malaria

“…In this study, kdr mutation was a significant risk factor to malaria incidence at a risk ratio of 1.06 (95% CI 1.02–1.10) for a 10% increase. The risk ratio was not high but similar to the results from the aforementioned study in Gambia where the odds ratio for a 10% increase in kdr mutation was 1.01–1.02 [66].…”

“…A recent study conducted in Gambia examined the risk for kdr mutation but failed to provide conclusive findings due to the co-occurrence of An. gambiae s.s. and homozygous L1014F mutation [66]. In this study, kdr mutation was a significant risk factor to malaria incidence at a risk ratio of 1.06 (95% CI 1.02–1.10) for a 10% increase.…”

Prediction ability of vector species, environmental characteristics and socio-economic factors for malaria risk in Sub-Saharan African Countries

“…coluzzi and An. gambiae are dominant, there is more malaria infection (Wilson et al 2018). This significant difference in malaria risk associated with species of Anopheles was clearly shown by the OR plot.…”

Correction to: Emergence of knock-down resistance in the Anopheles gambiae complex in the Upper River Region, The Gambia, and its relationship with malaria infection in children

“…Unfortunately, the original article [ 1 ] contained an error mistakenly carried forward by the Production department handling this article whereby some figures and their captions were interchanged. The correct figures (Figs.…”