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Raphaël N'Guessan, PhD
fr

Research

Insecticide resistance and the tools that still protect people. Four themes, one aim. Every claim below rests on published work.

Insecticide resistance

How Anopheles mosquitoes survive pyrethroids, from the kdr mutation to detoxifying enzymes, and what that resistance costs malaria control in the field. His 2010 review on the subject is among the most cited in the discipline.

The problem
Pyrethroids were for years the only insecticides on bed nets, and Anopheles mosquitoes across Africa have become resistant to them.
The approach
Measure resistance where it matters, in wild mosquitoes and in experimental huts where they fly freely, and link it to its mechanisms, the kdr mutation and detoxifying enzymes.
The impact
In Benin in 2007 he showed that treated nets killed 98% of susceptible mosquitoes but only 30% where kdr resistance was common. The warning helped turn the field toward new insecticides.

68 articles

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Nets and new chemistries

Evaluating the nets that still kill resistant mosquitoes, with chlorfenapyr, piperonyl butoxide and pyriproxyfen, from bioassay to experimental hut and cluster randomised trial.

The problem
Standard pyrethroid nets no longer kill resistant mosquitoes, and the tests used to approve nets were designed for pyrethroids only.
The approach
Adapt laboratory tests to insecticides that act differently, then compare nets in experimental huts and in cluster randomised trials in villages.
The impact
His 2016 trial of Interceptor G2 in Benin was among the first evidence for chlorfenapyr nets, which the World Health Organization now strongly recommends where resistance is intense.

64 articles

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Indoor residual spraying

Measuring what spraying the walls of homes really achieves against malaria in Africa, and which insecticides keep working once mosquitoes have adapted.

The problem
Programmes must choose between spraying products that differ in duration, cost and effect on resistant mosquitoes.
The approach
Pool experimental hut data on each insecticide and feed them into a model of malaria transmission.
The impact
A framework, published in Nature Communications in 2018, that helps decision makers compare the public health impact of spraying products.

11 articles

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Homes and new tools

Turning the house itself into a trap. Eave tubes and screening, the lethal house lure tested in a cluster randomised trial published in The Lancet, and attractive targeted sugar baits.

The problem
Mosquitoes enter homes at night through the eaves, and nets alone leave part of the transmission untouched.
The approach
Turn the house into a trap, with screening and EaveTubes that kill mosquitoes as they try to enter, and test sugar baits that deliver new insecticides.
The impact
In a trial in 40 villages of central Côte d'Ivoire, published in The Lancet in 2021, malaria fell from 2.29 to 1.43 cases per child per year in homes fitted with the lure.

24 articles

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