Resistance to insecticides in Anopheles gambiae complex in West Africa: A review of the current situation and the perspectives for malaria control

In West Africa, the Anopheles gambiae sensu lato (s.l.) complex mosquitoes are the main malaria vectors. Malaria control relies mainly on long-lasting insecticide-treated nets (LLINs) and to a lesser extent on indoor residual spray (IRS) of insecticides. Important progress has been made in terms of malaria morbidity and mortality in these past decades. Resistance to insecticides in An. gambiae s.l. was first attributed to their use in agriculture. Further, their use in public health increased selection pressure. Resistance has been recorded to the four main classes of insecticides used in public health in West Africa. However, the spread of insecticide resistance in West Africa is persistent due to the lack of management of resistance monitoring. Resistance to insecticides involves different mechanisms. Resistance to pyrethroids and organochlorines was caused by target modification such as some sodium channel mutations in addition to metabolic changes. Reduction of sensitivity to organophosphates and carbamates was caused by acetylcholinesterase mutations. Therefore, efforts should be made as quickly as possible to develop novel vector control techniques. Furthermore, it is also suggested to combine environmental, chemical, and biological management. In this review, we outline the insecticide resistance of Anopheles in West Africa and the current alternative tools for effective mosquito vector control.