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

Abstract

<ns3:p><ns3:bold>Background: </ns3:bold>Rio de Janeiro and Niterói are neighbouring cities in southeastern Brazil which experience large dengue epidemics every 2 to 5 years, with &gt;100,000 cases notified in epidemic years. Costs of vector control and direct and indirect costs due to the <ns3:italic>Aedes</ns3:italic>-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 <ns3:italic>Wolbachia</ns3:italic> method is a novel and self-sustaining approach for the biological control of <ns3:italic>Aedes</ns3:italic>-borne diseases, in which the transmission potential of <ns3:italic>Aedes aegypti</ns3:italic> mosquitoes is reduced by stably transfecting them with the <ns3:italic>Wolbachia</ns3:italic> bacterium (<ns3:italic>w</ns3:italic>Mel strain). This paper describes a study protocol for evaluating the effect of large-scale non-randomised releases of <ns3:italic>Wolbachia­</ns3:italic>-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.</ns3:p><ns3:p> <ns3:bold>Method:</ns3:bold> The <ns3:italic>Wolbachia</ns3:italic> releases during 2017-2019 covered a combined area of 170 km<ns3:sup>2</ns3:sup> 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 <ns3:italic>a priori</ns3:italic> 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 <ns3:italic>Aedes</ns3:italic>-borne disease activity utilising outbreak signals routinely used in public health disease surveillance.</ns3:p><ns3:p> <ns3:bold>Discussion:</ns3:bold> If the current project is successful, this model for control of mosquito-borne disease through <ns3:italic>Wolbachia</ns3:italic> releases can be expanded nationally and regionally.</ns3:p>