Background There is a steady rise in the global incidence of Aedes-borne arbovirus disease. It has become urgent to develop alternative solutions for mosquito vector control. We developed a new method of sterilization of male mosquitoes, with the goal to suppress a local Aedes aegypti population and to prevent the spread of dengue. Methods Sterile male mosquitoes were produced from a locally acquired Ae. aegypti colony by using a treatment that includes double-stranded RNA and thiotepa. A field study was conducted, with sterile mosquito releases being performed on a weekly basis in predefined areas. Two intervention periods (INT1 and INT2) were carried out, with treatment and control areas reversed between INT1 and INT2. Results During INT1, releases in the treated area resulted in up to 91.4% reduction of live progeny of field Ae. aegypti mosquitoes recorded over time, while the control neighborhoods (no releases of sterile male mosquitoes) remained highly infested. The successful implementation of the program during INT1 and INT2 were associated with a 15.9-fold and 13.7-fold lower incidences of dengue in the treated area compared to the control areas, respectively. Conclusions Our data show the success of this new SIT-based program in preventing the spread of dengue.

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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.

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Background: Dengue is a global problem that seems to be worsening, as hyper-urbanization associated with climate change has led to a significant increase in the abundance and geographical spread of its principal vector, the Aedes aegypti mosquito. The current available solutions, including vaccines and traditional vector-control methods, have not been able to stop the spread of dengue which shows the urgent need to implement alternative technologies as practical solutions. We recently presented Natural Vector Control (NVC), a new Sterile Insect Technology-based method that uses massive releases of sterile male mosquitoes produced from the combined treatment with dsRNA and thiotepa. In a previous pilot trial, two intervention periods over two epidemiological seasons were carried out, in which the control and treated areas were alternated between the epidemiological seasons, and we demonstrated the efficacy and safety of the method in suppressing the Ae. aegypti vector population and in blocking the occurrence of an outbreak of dengue in the treated areas. Here, we expand the use of the Natural Vector Control program in a large-scale 2-year period intervention carried out in an entire city located in southern Brazil. Methods: Sterile male mosquitoes were produced from locally sourced Ae. aegypti mosquitoes by using a treatment that includes double-stranded RNA and thiotepa. Weekly massive releases of sterile male mosquitoes were performed in predefined areas of Ortigueira from December 2020 to July 2022. Mosquito monitoring was performed by using ovitraps during the entire period of intervention. Dengue incidence data in Ortigueira and neighboring cities was obtained from the Brazilian National Disease Surveillance system. Results: During the two epidemiological seasons, the intervention in Ortigueira resulted in up to 98.7% suppression of live progeny of field Ae. aegypti mosquitoes recorded over time. More importantly, the program protected Ortigueira from a dengue outbreak that occurred in the neighboring cities: the dengue incidence in Ortigueira was 97% lower compared to 4 control cities. Conclusions: The Natural Vector Control method has again been shown to be a safe and efficient way to suppress Ae. aegypti field populations and prevent the occurrence of a dengue outbreak. Importantly, it has been shown to be applicable for large-scale, real-life conditions.