Successful suppression of a field population of Ae. aegypti mosquitoes using a novel biological vector control strategy is associated with significantly lower incidence of dengue

Background. Despite extensive efforts to prevent recurrent Aedes-borne arbovirus epidemics, there is a steady rise in their global incidence. Vaccines/treatments show very limited efficacy and together with the emergence of mosquito resistance to insecticides, it has become urgent to develop alternative solutions for efficient, sustainable and environmentally benign mosquito vector control. Here we present a new Sterile Insect Technology (SIT)-based program that uses large-scale releases of sterile male mosquitoes produced by a highly effective, safe and environmentally benign method. Methods and findings. To test the efficacy of this approach, a field trial was conducted in a Brazilian city (Jacarezinho), which presented a history of 3 epidemics of dengue in the past decade. Sterile male mosquitoes were produced from a locally acquired Aedes aegypti colony, and releases were carried out on a weekly basis for seven months in a predefined area. This treated area was matched to a control area, in terms of size, layout, historic mosquito infestation index, socioeconomic patterns and comparable prevalence of dengue cases in past outbreaks. Releases of sterile male mosquitoes resulted in up to 91.4% reduction of live progeny of field Ae. aegypti mosquitoes recorded over time. The reduction in the mosquito population was corroborated by the standard monitoring system (LIRAa index) as determined by the local municipality, which found that our treated neighborhoods were almost free of Ae. aegypti mosquitoes after 5 months of release, whereas neighborhoods adjacent to the treated area and the control neighborhoods were highly infested. Importantly, when a dengue outbreak started in Jacarezinho in March 2019, the effective mosquito population suppression was shown to be associated with a far lower incidence of dengue in the treated area (16 cases corresponding to 264 cases per 100,000 inhabitants) almost 16 times lower than the dengue incidence in the control area (198 cases corresponding to 4,360 dengue cases per 100,000 inhabitants). Conclusions. Our data present the first demonstration that a SIT-based intervention has the potential to prevent the spread of dengue, opening exciting new opportunities for preventing mosquito-borne disease.