Abstract
Due to the rapid extension of pyrethroid resistance in malaria vectors worldwide, manufacturers are developing new vector control tools including insecticide mixtures containing at least two active ingredients with different mode of action as part of insecticide resistance management. Olyset® Plus is a new long-lasting insecticidal net (LLIN) incorporating permethrin and a synergist, piperonyl butoxide (PBO), into its fibres in order to counteract metabolic-based pyrethroid resistance of mosquitoes. In this study, we evaluated the efficacy of Olyset® Plus both in laboratory and field against susceptible and multi-resistant malaria vectors and compared with Olyset Net, which is a permethrin incorporated into polyethylene net. In laboratory, Olyset® Plus performed better than Olyset® Net against susceptible Anopheles gambiae strain with a 2-day regeneration time owing to an improved permethrin bleeding rate with the new incorporation technology. It also performed better than Olyset® Net against multiple resistant populations of An. gambiae in experimental hut trials in West Africa. Moreover, the present study showed evidence for a benefit of incorporating a synergist, PBO, with a pyrethroid insecticide into mosquito netting. These results need to be further validated in a large-scale field trial to assess the durability and acceptability of this new tool for malaria vector control.
Highlights
The recent decline of malaria burden relies largely on the massive use of insecticide treated bed nets (ITNs) and the artemisinin combination therapy (ACT), supported by indoor residual spraying of insecticides (IRS) and intermittent preventive treatment during pregnancy [1]
This study demonstrated the benefit of incorporating piperonyl butoxide (PBO) and permethrin together in a long-lasting insecticidal net for malaria vector control
All treatments caused high mortality of Culicidae mosquitoes (85– 96%) relative to the untreated net (2%). Such a protective efficacy against nuisance causing mosquitoes is a positive factor as the personal protection against general blood sucking insects might be a key factor of acceptability and proper use of the long-lasting insecticidal net (LLIN)
Summary
The recent decline of malaria burden relies largely on the massive use of insecticide treated bed nets (ITNs) and the artemisinin combination therapy (ACT), supported by indoor residual spraying of insecticides (IRS) and intermittent preventive treatment during pregnancy [1]. Resistance mechanisms of malaria parasites to antimalarial drugs and Anopheles vectors to insecticides are challenging the efficacy of malaria control tools [2,3,4]. The efficacy of ITNs and long-lasting insecticidal nets (LLINs) so far relies exclusively on a single class of insecticides, the pyrethroids, to which various resistance mechanisms have spread among malaria vector populations [5,6,7]. Three main groups of enzymes have been identified: carboxylesterases, glutathione-S-transferases or GSTs and cytochrome P450-dependent monoxygenases. All these enzyme groups are involved in the resistance to pyrethroids used for malaria vector control [7]
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