Reduced Dengue Incidence Following Deployments of <i>Wolbachia</i>-Infected <i>Aedes aegypti</i> in Yogyakarta, Indonesia

Abstract

Background: Ae. 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. Methods: In Yogyakarta City, Indonesia, following an extensive community engagement campaign, wMel Wolbachia-carrying mosquitoes were released every two weeks for 13–15 rounds of release during a seven month period in 2016–17, in a contiguous 5 km2 area with population 65,000. A controlled interrupted time series (ITS) analysis of notified dengue cases was used to evaluate the epidemiological impact of Wolbachia deployments, in comparison to a predefined comparative untreated control area (3 km2 ; 34,000 population). Findings: Rapid and sustained introgression of wMel Wolbachia into local Ae. aegypti populations was achieved. Thirty-four dengue cases (hospitalised dengue hemorrhagic fever patients) 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 ITS 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%). Interpretation: Our findings demonstrate that Wolbachia establishment in Ae. aegypti reduces dengue incidence in an endemic setting in Indonesia. Funding Statement: This work was funded by the Tahija Foundation, Indonesia. Declaration of Interests: The authors declare no competing interests. Ethics Approval Statement: Approval to release Wolbachia mosquitoes was obtained from the provincial and city governments of Yogyakarta prior to releases. Ethical approval was obtained from the Universitas Gadjah Mada Faculty of Medicine, Public Health and Nursing Ethics Committee to release Wolbachia mosquitoes, for blood-feeding the mosquito colony on human volunteers, and to access non-identifiable aggregate data on monthly notified DHF and DF case numbers from the Yogyakarta DHO. Written agreement to share dengue surveillance data and non-identifiable individual dengue RDT results from Puskesmas clinics was obtained from Yogyakarta DHO. Verbal and written consent was obtained from heads of households for hosting a BG trap or MRC, and BG hosts were compensated for the cost of powering traps.