Systematic review of indoor residual spray efficacy and effectiveness against Plasmodium falciparum in Africa

Abstract

Indoor residual spraying (IRS) is an important part of malaria control. There is a growing list of insecticide classes; pyrethroids remain the principal insecticide used in bednets but recently, novel non-pyrethroid IRS products, with contrasting impacts, have been introduced. There is an urgent need to better assess product efficacy to help decision makers choose effective and relevant tools for mosquito control. Here we use experimental hut trial data to characterise the entomological efficacy of widely-used, novel IRS insecticides. We quantify their impact against pyrethroid-resistant mosquitoes and use a Plasmodium falciparum transmission model to predict the public health impact of different IRS insecticides. We report that long-lasting IRS formulations substantially reduce malaria, though their benefit over cheaper, shorter-lived formulations depends on local factors including bednet use, seasonality, endemicity and pyrethroid resistance status of local mosquito populations. We provide a framework to help decision makers evaluate IRS product effectiveness.

Risk factors for Burkitt lymphoma in East African children and minors: A case–control study in malaria‐endemic regions in Uganda, Tanzania and Kenya

“…Because IRS successfully suppressed malaria in areas where it was applied, 12,13 our results suggest that the early pre-eBL lesions continue to progress to eBL for up to 20 months, i.e., during the time when the IRS effects, which last 4-6 months per cycle and assuming 3-4 consecutive IRS cycles, are effectively suppressing malaria. 29 The early pre-eBL lesions are genetically unstable B cells 30 triggered by the historical malaria, 3 which irreversible secondary mutations 31 and undergo oligoclonal expansion stimulated by recurrent malaria 5 and through Darwinian selection 32 progress to eBL despite the absence of intense malaria pressure. The period of heightened risk of 1-2 years approximates the estimated latency period for eBL.…”

The role of windows of selection and windows of dominance in the evolution of insecticide resistance in human disease vectors

“…show a very similar pattern to the cone bioassays in Figure 4b. In addition, Churcher, Lissenden, Griffin, Worrall, and Ranson (2016) and Sherrard-Smith et al (2018) show evidence that bioassay results are good predictors of mortality in hut trials of insecticidal nets and sprays, respectively.…”

Mapping Trends in Insecticide Resistance Phenotypes in African Malaria Vectors

“…Until recently, pyrethroids were the only class approved for use in LLINs and recently launched new generation nets still use pyrethroids in combination with either an insect growth regulator, a pyrrole, or a synergist that inhibits the primary metabolic mechanism of pyrethroid resistance within mosquitoes 2, 3 . A wider range of options is available for indoor residual spraying (IRS), but pyrethroids are less expensive than many alternatives and are still used for IRS in malaria-endemic Sub-Saharan African countries 4, 5 .…”