Reduced dengue incidence following deployments of Wolbachia-infected Aedes aegypti in Yogyakarta, Indonesia: a quasi-experimental trial using controlled interrupted time series analysis

Abstract

AbstractBackgroundAe. aegypti mosquitoes stably transfected with the intracellular bacterium Wolbachia pipientis (wMel strain) have been deployed for the biocontrol of dengue and related arboviral diseases in multiple countries. Field releases in northern Australia have previously demonstrated near elimination of local dengue transmission from Wolbachia-treated communities, and pilot studies in Indonesia have demonstrated the feasibility and acceptability of the method. We conducted a quasi-experimental trial to evaluate the impact of scaled Wolbachia releases on dengue incidence in an endemic setting in Indonesia.Methods and findingsIn Yogyakarta City, Indonesia, following an extensive community engagement campaign, wMel Wolbachia-carrying mosquitoes were released every two weeks for 13–15 release rounds over seven months in 2016–17, in a contiguous 5 km2 area (population 65,000). A 3 km2 area (population 34,000) on the opposite side of the city was selected a priori as an untreated control area, on the basis of comparable socio-demographic characteristics and historical dengue incidence. Passive surveillance data on notified hospitalised dengue patients was used to evaluate the epidemiological impact of Wolbachia deployments, using controlled interrupted time series analysis. Rapid and sustained introgression of wMel Wolbachia into local Ae. aegypti populations was achieved. Thirty-four dengue cases were notified from the intervention area and 53 from the control area (incidence 26 vs 79 per 100,000 person-years) during the 24 months after Wolbachia was deployed. This corresponded in the regression model to a 73% reduction in dengue incidence (95% confidence interval 49%,86%) associated with the Wolbachia intervention. Exploratory analysis including an additional 6 months of post-intervention observations showed a small strengthening of this effect (30 vs 115 per 100,000 person-years; 76% reduction in incidence, 95%CI 60%,86%).ConclusionsThese findings demonstrate a significant reduction in dengue incidence following successful introgression of Wolbachia into local Ae. aegypti populations in an endemic setting in Indonesia. These results are consistent with previous field trials in northern Australia, and support the effectiveness of this novel approach for the control of dengue and other Aedes-borne diseases.