RESUMEN
Cambodia's goal to eliminate malaria by 2025 is challenged by persistent transmission in forest and forest fringe areas, where people are exposed to Anopheles mosquito bites during the day and night. Volatile pyrethroid spatial repellents (VPSRs) and insecticide-treated clothing (ITC) could address these gaps. This study evaluated the outdoor application of one passive transfluthrin-based VPSR, four etofenprox-ITCs paired with a picaridin topical repellent, and a combination of VPSR and ITC against wild Anopheles landing in Cambodia. A 7 × 7 Latin-square study was conducted over 49 collection nights in temporary open structures in Mondulkiri Province. All interventions substantially reduced Anopheles landing, with protective efficacy ranging from 61 to 95%. Mathematical modeling showed significant reductions in vectoral capacity, especially with the combined ITC and VPSR and VPSR alone, albeit with decreased effectiveness over time. These interventions have the potential to reduce outdoor and daytime Anopheles biting, offering valuable contributions to malaria elimination efforts in Cambodia and the Greater Mekong Subregion, contingent upon achieving effective coverage and adherence.
Asunto(s)
Anopheles , Bosques , Repelentes de Insectos , Malaria , Control de Mosquitos , Mosquitos Vectores , Piretrinas , Cambodia , Animales , Repelentes de Insectos/farmacología , Malaria/prevención & control , Malaria/transmisión , Anopheles/efectos de los fármacos , Mosquitos Vectores/efectos de los fármacos , Piretrinas/farmacología , Control de Mosquitos/métodos , Humanos , Insecticidas/farmacología , Mordeduras y Picaduras de Insectos/prevención & control , Ciclopropanos , FluorobencenosRESUMEN
BACKGROUND: Dengue is a global health problem of high significance, with 3.9 billion people at risk of infection. The geographic expansion of dengue virus (DENV) infection has resulted in increased frequency and severity of the disease, and the number of deaths has increased in recent years. Wolbachia,an intracellular bacterial endosymbiont, has been under investigation for several years as a novel dengue-control strategy. Some dengue vectors (Aedes mosquitoes) can be transinfected with specific strains of Wolbachia, which decreases their fitness (ability to survive and mate) and their ability to reproduce, inhibiting the replication of dengue. Both laboratory and field studies have demonstrated the potential effect of Wolbachia deployments on reducing dengue transmission, and modelling studies have suggested that this may be a self-sustaining strategy for dengue prevention, although long-term effects are yet to be elucidated. OBJECTIVES: To assess the efficacy of Wolbachia-carrying Aedes speciesdeployments (specifically wMel-, wMelPop-, and wAlbB- strains of Wolbachia) for preventing dengue virus infection. SEARCH METHODS: We searched CENTRAL, MEDLINE, Embase, four other databases, and two trial registries up to 24 January 2024. SELECTION CRITERIA: Randomized controlled trials (RCTs), including cluster-randomized controlled trials (cRCTs), conducted in dengue endemic or epidemic-prone settings were eligible. We sought studies that investigated the impact of Wolbachia-carrying Aedes deployments on epidemiological or entomological dengue-related outcomes, utilizing either the population replacement or population suppression strategy. DATA COLLECTION AND ANALYSIS: Two review authors independently selected eligible studies, extracted data, and assessed the risk of bias using the Cochrane RoB 2 tool. We used odds ratios (OR) with the corresponding 95% confidence intervals (CI) as the effect measure for dichotomous outcomes. For count/rate outcomes, we planned to use the rate ratio with 95% CI as the effect measure. We used adjusted measures of effect for cRCTs. We assessed the certainty of evidence using GRADE. MAIN RESULTS: One completed cRCT met our inclusion criteria, and we identified two further ongoing cRCTs. The included trial was conducted in an urban setting in Yogyakarta, Indonesia. It utilized a nested test-negative study design, whereby all participants aged three to 45 years who presented at healthcare centres with a fever were enrolled in the study provided they had resided in the study area for the previous 10 nights. The trial showed that wMel-Wolbachia infected Ae aegypti deployments probably reduce the odds of contracting virologically confirmed dengue by 77% (OR 0.23, 95% CI 0.15 to 0.35; 1 trial, 6306 participants; moderate-certainty evidence). The cluster-level prevalence of wMel Wolbachia-carrying mosquitoes remained high over two years in the intervention arm of the trial, reported as 95.8% (interquartile range 91.5 to 97.8) across 27 months in clusters receiving wMel-Wolbachia Ae aegypti deployments, but there were no reliable comparative data for this outcome. Other primary outcomes were the incidence of virologically confirmed dengue, the prevalence of dengue ribonucleic acid in the mosquito population, and mosquito density, but there were no data for these outcomes. Additionally, there were no data on adverse events. AUTHORS' CONCLUSIONS: The included trial demonstrates the potential significant impact of wMel-Wolbachia-carrying Ae aegypti mosquitoes on preventing dengue infection in an endemic setting, and supports evidence reported in non-randomized and uncontrolled studies. Further trials across a greater diversity of settings are required to confirm whether these findings apply to other locations and country settings, and greater reporting of acceptability and cost are important.