Insecticide-treated nets provide protection against malaria to children in an area of insecticide resistance in Southern Benin

Abstract

BackgroundMalaria control is heavily reliant on insecticides, especially pyrethroids. Resistance of mosquitoes to insecticides may threaten the effectiveness of insecticide-based vector control and lead to a resurgence of malaria in Africa.MethodsIn 21 villages in Southern Benin with high levels of insecticide resistance, the resistance status of local vectors was measured at the same time as the prevalence of malaria infection in resident children.ResultsChildren who used LLINs had lower levels of malaria infection [odds ratio = 0.76 (95% CI 0.59, 0.98, p = 0.033)]. There was no evidence that the effectiveness of nets was different in high and low resistance locations (p = 0.513). There was no association between village level resistance and village level malaria prevalence (p = 0.999).ConclusionsLLINs continue to offer individual protection against malaria infection in an area of high resistance. Insecticide resistance is not a reason to stop efforts to increase coverage of LLINs in Africa.

Empirical and theoretical investigation into the potential impacts of insecticide resistance on the effectiveness of insecticide‐treated bed nets

“…Our results are in line with those of a recent multicountry epidemiological evaluation, which found no evidence of an association between resistance (measured through standard WHO laboratory bioassays) and malaria prevalence or incidence, but did find significantly lower rates of infection in individuals using LLINs, indicating continued personal protection (Bradley et al., ; Ochomo et al., ; World Health Organization ). The pyrethroid susceptibility recorded in the multicountry evaluation was suggestive of moderate resistance.…”

“…A vector population is designated insecticide‐resistant when at least 10% of individuals survive the exposure. Although widely used for detecting resistance in field populations, it is now becoming clear that this phenotypic assay tells us little about how resistance interacts with malaria epidemiology (Bradley et al., ; Ochomo et al., ; Oxborough et al., ; Ranson & Lissenden, ; World Health Organization ). The reasons for this disconnect could be manifold (Rivero, Vézilier, Weill, Read, & Gandon, ).…”

Insecticide Resistance and Its Intensity in Populations of Malaria Vectors in Colombia

“…IRS failure has been observed when the levels of resistance intensity of the local vector populations are high [30]. This is less clear when using LLINs, attributed by some to the personal protection provided by the nets despite high level of vector resistance [31, 32]. WHO suggests interpreting resistance intensity assays as such that less than 98% mortality in mosquitoes exposed to 5 times and especially 10 times the discriminant concentration may indicate that control measures are ineffective in the field, indicating the urgency of developing adequate strategies for insecticide resistance management.…”

Insights from agriculture for the management of insecticide resistance in disease vectors

“…Despite the spread of phenotypic (based on bioassays such as the WHO tube test) and genotypic (based on genetic markers such as kdr ) resistance, the evidence for control failure due to resistance is equivocal, although perhaps clearer for IRS than for LLINs (Bradley et al., ; Maharaj, Mthembu, & Sharp, ; Wondji et al., ; World Health Organization, ; see also Huijbin, & Paaijmans, In Preparation).…”