Combining unrelated insecticides for improved control and management of insecticide resistant African malaria vectors

Doctoral thesis English OPEN
Ngufor, CA

It is now generally accepted that if nothing is done and insecticide resistance in malaria vectors especially to pyrethroids eventually led to widespread failure of current vector control strategies, the progress achieved so far in reducing the burden of malaria could be reversed. Interventions and operational tactics capable of controlling insecticide resistant malaria vector populations and delaying the evolution of resistance need to be urgently identified and properly investigated. One important insecticide resistance management strategy is to expose vector populations to a combination of unrelated insecticides.\ud In this study I investigated the potential of this combination concept to control and manage the spread of indoor resting insecticide resistant African malaria vectors. A series of field evaluations were performed in experimental huts in selected malaria endemic sites to investigate; 1.the impact of combining non-pyrethroid IRS or wall linings with pyrethroid LLINs against malaria vector populations with different levels of insecticide resistance and 2.The efficacy of LLINs treated with a pyrethroid and an alternative compound against pyrethroid resistant mosquitoes. The capacity of the combined intervention approach to delay the spread of insecticide resistance genes was investigated via genotyping studies.\ud I demonstrate that the use of combined interventions and mixture net with unrelated insecticides is an effective way to improve the control of pyrethroid resistance malaria vectors. However, the performance of these combinations will undoubtedly depend on the levels and type of resistance encountered. Where resistance to both insecticides exists, improved control is unlikely. While the use of single interventions would likely exacerbate resistance the combinations would be less beneficial for preventing selection of insecticide resistance when resistance genes are already well established. The impact of these findings on malaria vector control and resistance management is discussed.
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