A systematic review of interventions targeting Anopheles stephensi

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Background Anopheles stephensi, a malaria mosquito originally from South Asia and the Middle East, has been expanding across both Asia and Africa in recent decades. The invasion of this species into sub-Saharan Africa is of particular concern given its potential to increase malaria burden, especially in urban environments where An. stephensi thrives. Whilst surveillance of this vector in Africa has recently increased markedly there is a need to review the existing methods of An. stephensi control so that we can stop, rather than simply monitor, its spread in Africa. Methods We searched published papers in PubMed using An. stephensi and intervention-specific search terms. Forty-five full-text articles were screened for eligibility and all those that reported the use of interventions against An. stephensi, and the effect on malaria incidence, malaria prevalence or vector densities were included in the analysis. All data retrieved from the literature were from the native range of An. stephensi and from the period 1995 to 2018. Results Fourteen studies which met the inclusion criteria were included in the final analysis. The vector control interventions discussed were bio larvicides (n=3), repellents (n=1), Indoor Residual Spraying (n=2), Insecticide Treated Nets (n=3), insecticide-treated materials other than nets (n=3), the combined use of repellents and mosquito nets (n=1), and combination of biolarvicide and fish (n=1). Outcomes of the studies were primarily vector density (n=10) although some reported malaria incidence and/or prevalence (n=4). Conclusions Long-lasting insecticidal nets and indoor residual spraying are effective in controlling, An. stephensi-transmitted malaria and reducing vector density, with repellents offering a complementary approach, especially in urban areas where this vector thrives. The private sector can help scale up affordable repellent production in Africa. There is a need to address gaps in cost-effectiveness analysis and gather more epidemiological evidence to better assess the impact of malaria control strategies.