Quantifying the Epidemiological Impact of Targeted Indoor Residual Spraying on Aedes-borne Diseases

Emory University4,461 enrolled

Overview

The objective of this trial is evaluate the efficacy of Targeted Indoor Residual Spraying (TIRS) in preventing symptomatic disease caused by Aedes-borne diseases (ABDs) in children 2 to 15 years of age in the city of Merida, Yucatan State, Mexico.

Contemporaneous urban vector control (truck-mounted ultra-low volume spraying, thermal fogging, larviciding) has failed to contain dengue epidemics and to prevent the global range expansion of Aedes-borne diseases (ABDs: dengue, chikungunya, zika). Part of the challenge in sustaining effective ABD control emerges from the remarkable paucity of evidence about the epidemiological impact of any vector control method. Furthermore, the classic deployment of interventions in response to clinical cases fails to account for the important contribution of out-of-home human mobility and asymptomatic infections. The trial will be conducted in the city of Merida extending ongoing longitudinal cohort to follow a population of 4,600 children 2-15 years old randomly allocated to receive either TIRS treatment or not. If efficacious, TIRS will drive a paradigm shift in Aedes control by: considering Ae. aegypti behavior to rationally guide insecticide applications; the change to preventive control (pre- ABD transmission season rather than in response to symptomatic cases); the use of third generation insecticides to which Ae. Aegypti is susceptible.

Study Type

INTERVENTIONAL

Allocation

RANDOMIZED

Purpose

PREVENTION

Masking

NONE

Enrollment

4,461

Conditions

Aedes-borne Diseases Dengue Chikungunya Zika

Interventions

Targeted Indoor Residual Spraying (TIRS)OTHER

Spraying of insecticide Actellic 300CS will start in May or June extending for 1 to 2 months. Residents will be asked to temporarily leave the house during treatment and wait half an hour to one hour for the product to dry before re-entering the house. Insecticide application will follow strict protocol developed by the Centers for Disease Control and Prevention (CDC), Emory University, and the Universidad Autónoma de Yucatán.

Eligibility

Sex: ALLMin age: 2 YearsMax age: 15 Years

Medical Language ↔ Plain English

Inclusion Criteria: Household Level Inclusion Criteria: * Household is located within the bounds of a study cluster (5x5 city-block clusters) * City block has at least 60% premises that are residential Individual Level Inclusion Criteria: * 2 or more and up to 15 years of age at the time of initial enrollment * Living in a house that consented to TIRS (for children in TIRS cluster) Exclusion Criteria: Household Level Exclusion Criteria: * Households where study personnel identify a security risk (i.e., site where drugs are sold, residents are always drunk or hostile) * Sites where no residents spend time during the day (i.e. work 7days a week outside the home) * Inability for a resident to provide informed consent * Non-residential places (e.g., businesses, schools, markets, etc.) Individual Level Exclusion Criteria: * Less than 2 years of age or more than 15 years of age at the time of enrollment * Not living in a house that consented to TIRS (for children in TIRS cluster) * Having a medical condition that prevents implementation of study procedures * Temporary visitor to household * Plans to leave study area within next 12 months

Locations (1)

Universidad Autonoma de Yucatan

Mérida, Yucatán, Mexico

Outcomes

Primary Outcomes

Number of Symptomatic Participants Testing Positive for Aedes-borne Virus Infections That Are Laboratory Confirmed or Serologically

The number of symptomatic children with laboratory confirmed, by reverse transcription-polymerase chain reaction (RT-PCR) or immunoglobulin M/ immunoglobulin G (IgM/IgG) enzyme-linked immunosorbent assay (ELISA), Aedes-borne Viruses infections. The number of any Aedes-borne virus infection during three seasons of high transmission is described, as well as the number of Dengue virus (DENV), Chikungunya virus (CHIKV), Zika virus (ZIKV) and coinfections.

Time frame: 18 months of active surveillance during high transmission seasons (each 6 months in duration) during 3 years (July through December in 2021, 2022, and 2023)

Secondary Outcomes

Number Positive Tests of Laboratory Confirmed Aedes-borne Viruses Infections By Season

Number of laboratory confirmed (IgG ELISA and neutralization testing) Aedes-borne Viruses (DENV, CHIKV and ZIKV) in annual surveillance samples.

Time frame: Up to 36 months, during serosurvey seasons 2021-2022, 2022-2023, and 2023-2024

Ae. Aegypti Mosquito Infection Rate With Aedes-borne Viruses (DENV, CHIKV and ZIKV)

Ae. aegypti mosquito infection rate with Aedes-borne Viruses (DENV, CHIKV and ZIKV) assessed by the number of positive RT-PCR tests. Infection is mosquitoes is analyzed by collecting binary data (a mosquito pool is either infected or not) and transforming that into minimum infection rates (MIR) with the calculation: (1/number of mosquitoes in the pool) times 1000. Households were randomly selected for testing; houses were eligible for testing if they were located within the central blocks and had at least one child enrolled in the study.

Time frame: Up to 6 months (mosquito pools were collected during the 6 months post TIRS spraying samplings in 2021)

Ae. Aegypti Indoor Entomological Index of Adult Mosquito Abundance

The Ae. aegypti indoor entomological index of adult mosquito presence/abundance is calculated as the number of adult mosquitoes per house. Higher values mean that more mosquitoes are found within houses.

Data from ClinicalTrials.gov

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