Large-scale deployment of SIT-based technology in a Brazilian city prevented Dengue outbreak

BackgroundDengue 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. MethodsSterile 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. ResultsDuring 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. ConclusionsThe 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.