The impact of city-wide deployment of Wolbachia-carrying mosquitoes on arboviral disease incidence in Medellín and Bello, Colombia: study protocol for an interrupted time-series analysis and a test-negative design study [version 2; peer review: 2 approved, 1 approved with reservations]

• Published in: F1000 research Vol. 8; p. 1327
• Main Authors: Velez, Ivan D, Santacruz, Eduardo, Kutcher, Simon C, Duque, Sandra L, Uribe, Alexander, Barajas, Jovany, Gonzalez, Sandra, Patino, Ana Cristina, Zuluaga, Lina, Martínez, Luis, Muñoz, Estefanía, Mejia, María Camila, Arbelaez, María Patricia, Pulido, Henry, Jewell, Nicholas P, Dufault, Suzanne M, O'Neill, Scott L, Simmons, Cameron P, Anders, Katherine L, Tanamas, Stephanie K
• Format: Journal Article
• Language: English
• Published: London Faculty of 1000 Ltd 2020; F1000 Research Limited
• Subjects: Aedes aegypti; Chikungunya virus; Culicidae; Demography; Dengue fever; Disease; Disease transmission; Epidemics; Epidemiology; Mosquitoes; Population; Primary care; Public health; Study Protocol; Time series; Tropical environment; Vaccines; Wolbachia; Zika virus; Colombia; Latin America; Colombia; Wolbachia; interrupted time series; dengue; disease surveillance; chikungunya; vector-borne disease; Zika
• ISSN: 2046-1402; 2046-1402
• DOI: 10.12688/f1000research.19858.2

Background: Dengue, chikungunya and Zika are viral infections transmitted by
Aedes aegypti mosquitoes, and present major public health challenges in tropical regions. Traditional vector control methods have been ineffective at halting disease transmission. The World Mosquito Program has developed a novel approach to arbovirus control using
Ae. aegypti stably transfected with the
Wolbachia bacterium, which have significantly reduced ability to transmit dengue, Zika and chikungunya in laboratory experiments. Field releases in eight countries have demonstrated
Wolbachia establishment in local
Ae. aegypti populations.
Methods: We describe a pragmatic approach to measuring the epidemiological impact of city-wide
Wolbachia deployments in Bello and Medellín, Colombia. First, an interrupted time-series analysis will compare the incidence of dengue, chikungunya and Zika case notifications before and after
Wolbachia releases, across the two municipalities. Second, a prospective case-control study using a test-negative design will be conducted in one quadrant of Medellín. Three of the six contiguous release zones in the case-control area were allocated to receive the first
Wolbachia deployments in the city and three to be treated last, approximating a parallel two-arm trial for the >12-month period during which
Wolbachia exposure remains discordant. Allocation, although non-random, aimed to maximise balance between arms in historical dengue incidence and demographics. Arboviral disease cases and arbovirus-negative controls will be enrolled concurrently from febrile patients presenting to primary care, with case/control status classified retrospectively following laboratory diagnostic testing. Intervention effect is estimated from an aggregate odds ratio comparing
Wolbachia-exposure odds among test-positive cases versus test-negative controls.
Discussion: The study findings will add to an accumulating body of evidence from global field sites on the efficacy of the
Wolbachia method in reducing arboviral disease incidence, and can inform decisions on wider public health implementation of this intervention in the Americas and beyond.
Trial registration: ClinicalTrials.gov:
NCT03631719. Registered on 15 August 2018.