Last updated on March 2019

Wolbachia Disease Impact in Medellin and Bello


Brief description of study

Study setting: Medellin and Bello municipalities, Colombia Health condition(s) studied: Dengue, Zika and chikungunya virus infection Intervention: Deployment of Wolbachia-infected Aedes aegypti mosquitoes in Medellin and Bello, in addition to standard practice dengue control activities.

Primary endpoints and analysis:

Strategy 1. Measurement of incidence rate ratio of dengue cases before and after Wolbachia deployment as measured by the public health surveillance system in Medellin and Bello.

Strategy 2. Estimate of the odds of symptomatic, virologically-confirmed dengue virus (DENV) infection of any severity in the case-control study area in Medellin. The intention-to-treat analysis will consider Wolbachia exposure as binary depending on the location of the study participants' residence in the period 3-10 days prior to study enrolment.

Detailed Study Description

1.1. Selection and enrolment of participants Enrolment of patients will commence after completion of Wolbachia releases in the early zones. Study processes for enrolling patients presenting with febrile illness will be established at a network of primary health care facilities that serve the population who reside in the study area. Trained research staff will be employed to assist with study processes in each site.

Participants will be enrolled from within the population of patients (aged 3 years old) presenting with undifferentiated fever of 1-4 days' duration. All patients meeting the inclusion criteria will be eligible for enrolment and will be asked to provide written informed consent before participating in the study.

1.1.1. Recruitment procedures All eligible participants meeting study inclusion criteria will be invited to enroll continuously throughout the study period. Recruitment will occur during normal clinic hours. Participants will be managed according to standard clinical practice by the attending physicians. Recruitment rates in each clinic and across the study site as a whole will be monitored weekly, including a review of the screening logs to identify the proportion of eligible participants who did not consent to participate. The field coordinator will make regular visits to low-enrolling clinics to identify clinic-based, patient-based or other causes for low recruitment, and put measures in place to address these.

1.1.2. Screening log book All patients presenting with febrile illness will be screened against the study inclusion criteria by trained staff. All eligible febrile individuals will be recorded in a screening log and invited to participate. Participation status (consent/decline) will be recorded against each participant in the log.

1.1.3. Informed consent procedures Written informed consent will be sought from participants (or their guardian where the participant is a minor) by trained local staff, after explaining the study objectives, processes, data, and sample collection, and the participant has had an opportunity to ask questions. A verbal explanation of the written Explanatory Statement will be provided to all participants in the local language. In addition, participants aged between 7 and 17 years will be invited to sign an assent form indicating they understand the research and agree to participate. Data and sample collection procedures 1.1.4. Data to be collected A unique identifier will be assigned to each participant at enrollment. Basic demographic details, eligibility against the inclusion criteria and illness onset date will be recorded in a standardized case report form.

Clinical Study Identifier: NCT03631719

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