Search

Background: Ae. aegypti mosquitoes stably transfected with the intracellular bacterium Wolbachia pipientis ( w Mel strain) have been deployed for 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: In Yogyakarta City, Indonesia, following extensive community engagement, w Mel Wolbachia -carrying mosquitoes were released every two weeks for 13-15 rounds over seven months in 2016-17, in a contiguous 5 km 2 area (population 65,000). A 3 km 2 area (population 34,000) on the opposite side of the city was selected a priori as an untreated control area. Passive surveillance data on notified hospitalised dengue patients was used to evaluate the epidemiological impact of Wolbachia deployments, using controlled interrupted time-series analysis. Results: Rapid and sustained introgression of w Mel 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 24 months following Wolbachia deployment. 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 6 months additional 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%). Conclusions: We demonstrate a significant reduction in dengue incidence following successful introgression of Wolbachia into local Ae. aegypti populations in an endemic setting in Indonesia. These findings are consistent with previous field trials in northern Australia, and support the effectiveness of this novel approach for dengue control., Competing Interests: No competing interests were disclosed., (Copyright: © 2020 Indriani C et al.)

Background: The w Mel strain of Wolbachia has been successfully introduced into Aedes aegypti mosquitoes and subsequently shown in laboratory studies to reduce transmission of a range of viruses including dengue, Zika, chikungunya, yellow fever, and Mayaro viruses that cause human disease. Here we report the entomological and epidemiological outcomes of staged deployment of Wolbachia across nearly all significant dengue transmission risk areas in Australia. Methods: The  w Mel strain of  Wolbachia  was backcrossed into the local  Aedes aegypti  genotype (Cairns and Townsville backgrounds) and mosquitoes were released in the field by staff or via community assisted methods. Mosquito monitoring was undertaken and mosquitoes were screened for the presence of  Wolbachia . Dengue case notifications were used to track dengue incidence in each location before and after releases. Results: Empirical analyses of the Wolbachia mosquito releases, including data on the density, frequency and duration of Wolbachia mosquito releases, indicate that Wolbachia can be readily established in local mosquito populations, using a variety of deployment options and over short release durations (mean release period 11 weeks, range 2-22 weeks). Importantly, Wolbachia frequencies have remained stable in mosquito populations since releases for up to 8 years. Analysis of dengue case notifications data demonstrates near-elimination of local dengue transmission for the past five years in locations where Wolbachia has been established. The regression model estimate of Wolbachia intervention effect from interrupted time series analyses of case notifications data prior to and after releases, indicated a 96% reduction in dengue incidence in Wolbachia treated populations (95% confidence interval: 84 - 99%). Conclusion: Deployment of the w Mel strain of Wolbachia into local Ae. aegypti populations across the Australian regional cities of Cairns and most smaller regional communities with a past history of dengue has resulted in the reduction of local dengue transmission across all deployment areas., Competing Interests: No competing interests were disclosed., (Copyright: © 2020 Ryan PA et al.)

Background: The w Mel strain of Wolbachia has been successfully introduced into Aedes aegypti mosquitoes and subsequently shown in laboratory studies to reduce transmission of a range of viruses including dengue, Zika, chikungunya, yellow fever, and Mayaro viruses that cause human disease. Here we report the entomological and epidemiological outcomes of staged deployment of Wolbachia across nearly all significant dengue transmission risk areas in Australia. Methods: The  w Mel strain of  Wolbachia  was backcrossed into the local  Aedes aegypti  genotype (Cairns and Townsville backgrounds) and mosquitoes were released in the field by staff or via community assisted methods. Mosquito monitoring was undertaken and mosquitoes were screened for the presence of  Wolbachia . Dengue case notifications were used to track dengue incidence in each location before and after releases. Results: Empirical analyses of the Wolbachia mosquito releases, including data on the density, frequency and duration of Wolbachia mosquito releases, indicate that Wolbachia can be readily established in local mosquito populations, using a variety of deployment options and over short release durations (mean release period 11 weeks, range 2-22 weeks). Importantly, Wolbachia frequencies have remained stable in mosquito populations since releases for up to 8 years. Analysis of dengue case notifications data demonstrates near-elimination of local dengue transmission for the past five years in locations where Wolbachia has been established. The regression model estimate of Wolbachia intervention effect from interrupted time series analyses of case notifications data prior to and after releases, indicated a 96% reduction in dengue incidence in Wolbachia treated populations (95% confidence interval: 84 - 99%). Conclusion: Deployment of the w Mel strain of Wolbachia into local Ae. aegypti populations across the Australian regional cities of Cairns and most smaller regional communities with a past history of dengue has resulted in the reduction of local dengue transmission across all deployment areas., Competing Interests: No competing interests were disclosed., (Copyright: © 2019 Ryan PA et al.)

Background : A number of new technologies are under development for the control of mosquito transmitted viruses, such as dengue, chikungunya and Zika that all require the release of modified mosquitoes into the environment. None of these technologies has been able to demonstrate evidence that they can be implemented at a scale beyond small pilots. Here we report the first successful citywide scaled deployment of Wolbachia in the northern Australian city of Townsville. Methods : The w Mel strain of Wolbachia was backcrossed into a local Aedes aegypti genotype and mass reared mosquitoes were deployed as eggs using mosquito release containers (MRCs). In initial stages these releases were undertaken by program staff but in later stages this was replaced by direct community release including the development of a school program that saw children undertake releases. Mosquito monitoring was undertaken with Biogents Sentinel (BGS) traps and individual mosquitoes were screened for the presence of Wolbachia with a Taqman qPCR or LAMP diagnostic assay. Dengue case notifications from Queensland Health Communicable Disease Branch were used to track dengue cases in the city before and after release. Results : Wolbachia was successfully established into local Ae. aegypti mosquitoes across 66 km 2 in four stages over 28 months with full community support.  A feature of the program was the development of a scaled approach to community engagement. Wolbachia frequencies have remained stable since deployment and to date no local dengue transmission has been confirmed in any area of Townsville after Wolbachia has established, despite local transmission events every year for the prior 13 years and an epidemiological context of increasing imported cases. Conclusion : Deployment of Wolbachia into Ae. aegypti populations can be readily scaled to areas of ~60km 2 quickly and cost effectively and appears in this context to be effective at stopping local dengue transmission., Competing Interests: No competing interests were disclosed.