Abstract
BackgroundScaling-up of effective anti-malarial control strategies in Central-West region of Senegal has resulted in the sharp decline in malaria prevalence in this area. However, despite these strategies, residual malaria transmission has been observed in some villages (hot spots). The objective of this study was to assess the impact of indoor residual spraying (IRS) with pirimiphos-methyl on malaria transmission in hot spot areas.MethodsThe malaria vector population dynamics were monitored in each of the six selected villages (4 of which used IRS, 2 were unsprayed control areas) using overnight human landing catches (HLC) and pyrethrum spray catches (PSC). The host source of blood meals from freshly fed females collected using PSC was identified using the direct ELISA method. Females caught through HLC were tested by ELISA for the detection of Plasmodium falciparum circumsporozoite protein and Anopheles gambiae complex was identified using PCR.ResultsPreliminary data shown that the densities of Anopheles populations were significantly lower in the sprayed areas (179/702) compared to the control. Overall, malaria transmission risk was 14 times lower in the intervention zone (0.94) compared to the control zone (12.7). In the control areas, three Anopheles species belonging to the Gambiae complex (Anopheles arabiensis, Anopheles coluzzii and Anopheles melas) maintained the transmission, while only An. coluzzii was infective in the sprayed areas.ConclusionThe preliminary data from this pilot study showed that IRS with the CS formulation of pirimiphos-methyl is likely very effective in reducing malaria transmission risk. However, additional studies including further longitudinal entomological surveys as well as ecological and ethological and genetical characterization of vectors species and their populations are needed to better characterize the entomological impact of indoor residual spraying with pirimiphos-methyl in the residual transmission areas of Senegal.
Highlights
Scaling-up of effective anti-malarial control strategies in Central-West region of Senegal has resulted in the sharp decline in malaria prevalence in this area
In addition to long-lasting insecticide-treated nets (LLINs) and indoor residual spraying (IRS), between 2008 and 2010 four health districts located in the administrative departments of Fatick, Mbour, Niakhar and Bambey were selected by the Parasitology Department of the Université Cheikh Anta Diop of Dakar in collaboration with the National Malaria Control Programme (NMCP) to implement the roll-out of a pilot chemoprevention strategy named Seasonal Malaria Chemo-prevention (SMC) [5]
Additional studies on the ecological, ethological and genetical characteristics of vectors populations are needed to better characterize the entomological impact of indoor residual spraying with pirimiphos-methyl in the residual transmission areas of Senegal
Summary
Scaling-up of effective anti-malarial control strategies in Central-West region of Senegal has resulted in the sharp decline in malaria prevalence in this area. Despite these strategies, residual malaria transmission has been observed in some villages (hot spots). Sy et al Malar J (2018) 17:64 effective prevention strategies, with long-lasting insecticide-treated nets (LLINs) and indoor residual spraying (IRS) being the core interventions [1]. These two measures account for almost 60% of global investment in malaria control [2]. The SMC strategy involves administration of a single dose of sulfadoxine-pyrimethamine and amodiaquine to children under 10 during the peak malaria transmission season
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