The impact of large-scale deployment of Wolbachia mosquitoes on arboviral disease incidence in Rio de Janeiro and Niterói, Brazil: study protocol for a controlled interrupted time series analysis using routine disease surveillance data

Abstract

Background: Rio de Janeiro and Niterói municipalities in southeastern Brazil experience large dengue epidemics every 2 to 5 years, with >100,000 cases notified in epidemic years. Costs of vector control and direct and indirect costs due to the Aedes-borne diseases dengue, chikungunya and Zika were estimated to total $650 million USD in 2016, but traditional vector control strategies have not been effective in preventing arboviral disease outbreaks. The Wolbachia method is a novel and self-sustaining approach for the biological control of arboviral diseases, in which the transmission potential of Ae. aegypti mosquitoes is reduced by stably transfecting them with the Wolbachia bacterium. This paper describes a study protocol for evaluating the effect of large-scale non-randomised releases of Wolbachia mosquitoes on the incidence of dengue, Zika and chikungunya in the municipalities of Niterói and Rio de Janeiro. This follows a lead-in period since 2014 involving intensive community engagement, regulatory and public approval, entomological surveys, and small-scale pilot releases. Method: The planned releases during 2017-2019 cover a combined area of 121 km2 with a resident population of 1.1 million, across the two cities. Untreated areas with comparable historical dengue profiles and sociodemographic characteristics have been identified a priori as comparative control areas in each municipality. The proposed pragmatic epidemiological approach combines a controlled interrupted time series analysis of routinely notified suspected and laboratory-confirmed arboviral cases, together with monitoring of arbovirus activity utilising outbreak signals routinely used in public health disease surveillance. Discussion: If the current project is successful, this model for control of arboviral disease through Wolbachia releases can be expanded nationally and regionally.