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

<b>Background:</b> Rio de Janeiro and Niterói are neighbouring cities in southeastern Brazil which 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 <i>Aedes</i>-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 mosquito-borne disease outbreaks. The <i>Wolbachia</i> method is a novel and self-sustaining approach for the biological control of <i>Aedes</i>-borne diseases, in which the transmission potential of <i>Aedes aegypti</i> mosquitoes is reduced by stably transfecting them with the <i>Wolbachia</i> bacterium ( <i>w</i>Mel strain). This paper describes a study protocol for evaluating the effect of large-scale non-randomised releases of <i>Wolbachia-</i>-infected mosquitoes on the incidence of dengue, Zika and chikungunya in the two cities 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. <b>Method:</b> The <i>Wolbachia</i> releases during 2017-2019 covered a combined area of 170 km ² with a resident population of 1.2 million, across Niterói and Rio de Janeiro. Untreated areas with comparable historical dengue profiles and demographic characteristics have been identified <i>a priori</i> as comparative control areas in each city. The proposed pragmatic epidemiological approach combines a controlled interrupted time series analysis of routinely notified suspected and laboratory-confirmed dengue and chikungunya cases, together with monitoring of <i>Aedes</i>-borne disease activity utilising outbreak signals routinely used in public health disease surveillance. <b>Discussion:</b> If the current project is successful, this model for control of mosquito-borne disease through <i>Wolbachia</i> releases can be expanded nationally and regionally.