Reduced dengue incidence following city-wide wMel Wolbachia mosquito releases throughout three Colombian cities: Interrupted time series analysis and a prospective case-control study.

• Published in: PLOS Neglected Tropical Diseases
• Main Authors: Ivan Dario Velez, Stephanie K Tanamas, Maria Patricia Arbelaez, Simon C Kutcher, Sandra L Duque, Alexander Uribe, Lina Zuluaga, Luis Martínez, Ana Cristina Patiño, Jovany Barajas, Estefanía Muñoz, Maria Camila Mejia Torres, Sandra Uribe, Sandra Porras, Rita Almanza, Henry Pulido, Scott L O'Neill, Eduardo Santacruz-Sanmartin, Sandra Gonzalez, Peter A Ryan, Jai A Denton, Nicholas P Jewell, Suzanne M Dufault, Cameron P Simmons, Katherine L Anders
• Format: Article in Journal/Newspaper
• Language: English
• Published: Public Library of Science (PLoS) 2023
• Subjects: Arctic medicine. Tropical medicine; RC955-962; Public aspects of medicine; RA1-1270; Arctic; Bello
• Online Access: https://doi.org/10.1371/journal.pntd.0011713; https://doaj.org/article/3531382218da43138231d593291254b2

Background The introduction of Wolbachia (wMel strain) into Aedes aegypti mosquitoes reduces their capacity to transmit dengue and other arboviruses. Randomised and non-randomised studies in multiple countries have shown significant reductions in dengue incidence following field releases of wMel-infected Ae. aegypti. We report the public health outcomes from phased, large-scale releases of wMel-Ae. aegypti mosquitoes throughout three contiguous cities in the Aburrá Valley, Colombia. Methodology/principal findings Following pilot releases in 2015-2016, staged city-wide wMel-Ae. aegypti deployments were undertaken in the cities of Bello, Medellín and Itagüí (3.3 million people) between October 2016 and April 2022. The impact of the Wolbachia intervention on dengue incidence was evaluated in two parallel studies. A quasi-experimental study using interrupted time series analysis showed notified dengue case incidence was reduced by 95% in Bello and Medellín and 97% in Itagüí, following establishment of wMel at ≥60% prevalence, compared to the pre-intervention period and after adjusting for seasonal trends. A concurrent clinic-based case-control study with a test-negative design was unable to attain the target sample size of 63 enrolled virologically-confirmed dengue (VCD) cases between May 2019 and December 2021, consistent with low dengue incidence throughout the Aburrá Valley following wMel deployments. Nevertheless, VCD incidence was 45% lower (OR 0.55 [95% CI 0.25, 1.17]) and combined VCD/presumptive dengue incidence was 47% lower (OR 0.53 [95% CI 0.30, 0.93]) among participants resident in wMel-treated versus untreated neighbourhoods. Conclusions/significance Stable introduction of wMel into local Ae. aegypti populations was associated with a significant and sustained reduction in dengue incidence across three Colombian cities. These results from the largest contiguous Wolbachia releases to-date demonstrate the real-world effectiveness of the method across large urban populations and, alongside previously ...