Malaria control dynamics may explain inconsistent outcomes from bednet trials: a modeling study

Abstract

BACKGROUND Long-lasting insecticidal bednets have unparalleled efficacy in reducing malaria burden. However, insecticidal resistance and bednet avoidance behaviors among the mosquito vectors are now widespread.METHODS Reviewing the relevant field and semi-field studies highlights the ubiquity of zoophagic and spatiotemporal (biting outdoors or at different times of day) plasticity among vectors in response to bednet deployment. Transmission models coupled with the population genetics of vectors are developed to assess the impact on malaria control caused by insecticide resistance and the avoidance behaviors of mosquitoes. RESULTS Interactions between physiological resistance and behavioral resilience among mosquitovectors can significantly impact malaria control efforts both in the short-and long-term. The possibility of misleading observations from injudiciously timed assessments of malaria control programs is demonstrated through simulation.CONCLUSIONS Currently, there are no guidelines to inform when during a bednet trial its effectiveness should be measured. The importance of this oversight is described in the context of recent randomized controlled bednet trials.