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Negative Cross Resistance Mediated by Co-Treated Bed Nets: A Potential Means of Restoring Pyrethroid-Susceptibility to Malaria Vectors |
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| Authors: | Michael T White Dickson Lwetoijera John Marshall Geoffrey Caron-Lormier David A Bohan Ian Denholm Gregor J Devine |
| Institution: | 1. MRC Centre for Outbreak Analysis and Modelling, Imperial College, London, United Kingdom.; 2. Ifakara Health Institute, Ifakara, Tanzania.; 3. University of Nottingham, Sutton Bonington, Leicestershire, United Kingdom.; 4. INRA, UMR 1347 Agroécologie, Pôle ECOLDUR, Dijon, France.; 5. University of Hertfordshire, Hatfield, Hertfordshire, United Kingdom.; 6. QIMR Berghofer Medical Research Institute, Brisbane, Australia.; Institut Pasteur, France, |
| Abstract: | Insecticide-treated nets and indoor residual spray programs for malaria control are entirely dependent on pyrethroid insecticides. The ubiquitous exposure of Anopheles mosquitoes to this chemistry has selected for resistance in a number of populations. This threatens the sustainability of our most effective interventions but no operationally practicable way of resolving the problem currently exists. One innovative solution involves the co-application of a powerful chemosterilant (pyriproxyfen or PPF) to bed nets that are usually treated only with pyrethroids. Resistant mosquitoes that are unaffected by the pyrethroid component of a PPF/pyrethroid co-treatment remain vulnerable to PPF. There is a differential impact of PPF on pyrethroid-resistant and susceptible mosquitoes that is modulated by the mosquito’s behavioural response at co-treated surfaces. This imposes a specific fitness cost on pyrethroid-resistant phenotypes and can reverse selection. The concept is demonstrated using a mathematical model. |
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