Background: There has been rapid scale-up of malaria vector control in the last ten years. Both of the primary control
strategies, long-lasting pyrethroid treated nets and indoor residual spraying, rely on the use of a limited number of
insecticides. Insecticide resistance, as measured by bioassay, has rapidly increased in prevalence and has come to the
forefront as an issue that needs to be addressed to maintain the sustainability of malaria control and the drive to
elimination. Zambia’s programme reported high levels of resistance to the insecticides it used in 2010, and, as a result,
increased its investment in resistance monitoring to support informed resistance management decisions.
Methodology/Principal Findings: A country-wide survey on insecticide resistance in Zambian malaria vectors was
performed using WHO bioassays to detect resistant phenotypes. Molecular techniques were used to detect target-site
mutations and microarray to detect metabolic resistance mechanisms. Anopheles gambiae s.s. was resistant to pyrethroids,
DDT and carbamates, with potential organophosphate resistance in one population. The resistant phenotypes were
conferred by both target-site and metabolic mechanisms. Anopheles funestus s.s. was largely resistant to pyrethroids and carbamates, with potential resistance to DDT in two locations. The resistant phenotypes were conferred by elevated levels of cytochrome p450s.
Conclusions/Significance: Currently, the Zambia National Malaria Control Centre is using these results to inform their vector control strategy. The methods employed here can serve as a template to all malaria-endemic countries striving to create a sustainable insecticide resistance management plan