3. Producción
Browse
3 results
Search Results
- Some of the metrics are blocked by yourconsent settings
Item type:Publication, Efficacy of a spatial repellent for control of Aedes-borne virus transmission: a cluster randomized trial in Iquitos, Peru(Cold Spring Harbor Laboratory, 2021-03-05)Over half the world’s population is at risk for viruses transmitted by Aedes mosquitoes, such as, dengue and Zika. The primary vector, Aedes aegypti , thrives in urban environments. Despite decades of effort, cases and geographic range of Aedes -borne viruses (ABV) continue to expand. Rigorously proven vector control interventions that measure protective efficacy against ABV diseases is limited to Wolbachia in a single trial in Indonesia, and do not include any chemical intervention. Spatial repellents, a new option for efficient deployment, are designed to decrease human exposure to ABV by releasing active ingredients into the air that disrupt mosquito-human contact. A parallel, cluster-randomized controlled trial was conducted in Iquitos, Peru to quantify the impact of a transfluthrin-based spatial repellent on human ABV infection. From 2,907 households across 26 clusters (13 per arm), 1,578 participants were assessed for seroconversion (primary endpoint) by survival analysis. Incidence of acute disease was calculated among 16,683 participants (secondary endpoint). Adult mosquito collections were conducted to compare Ae. aegypti abundance, blood-fed rate and parity status through mixed effect difference-in-difference analyses. The spatial repellent significantly reduced ABV infection by 34·1% (1-sided 95% CI lower limit, 6·9%; 1-sided p-value=0·0236, z=1·98). Aedes aegypti abundance and blood-fed rates were significantly reduced by 28·6% (95% CI 24·1%, ∞); z=-9·11) and 12·4% (95% CI 4·2%, ∞); z=-2·43), respectively. Our trial provides the first conclusive statistical evidence from a pre-planned cluster randomized controlled clinical trial with a pre-defined effect size on the primary endpoint that was appropriate powered to prospectively quantify and statistically test for a difference in the impact of a chemical intervention, in this case a spatial repellent, to reduce the risk of ABV transmission compared to a placebo. Significance Statement Vector interventions are needed for Aedes -borne viral diseases (dengue, Zika, chikungunya, and yellow fever) prevention, but their application is hindered by the lack of evidence proving they prevent infection or disease. Our research reports the first conclusive statistical evidence from a pre-planned, prospective cluster-randomized, controlled clinical trial (cRCT) of significant protective efficacy (34.1% hazard estimate) against human Aedes -borne virus (ABV) infection by a chemical-based vector control intervention, the most commonly used intervention category among all ABV World Health Organization recommendations. A previous trial against malaria in Indonesia indicated a positive trend but did not detect a significant effect. Results from our ABV study will help guide public health authorities responsible for operational management and world-wide prevention of ABV, and incentivize new strategies for disease prevention. - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Molecular characterization by multilocus sequence typing and diversity analysis of Rickettsia asembonensis in Peru(Mary Ann Liebert Inc., 2022-03-01)Despite several reports worldwide documenting the presence of Rickettsia asembonensis in samples derived from ectoparasites, animals and more recently humans, genomic information of these specimens remains scarce, and when available, is usually limited to small genomic fragments of limited value. We generated complete sequences for two conserved (17-kDa antigen gene and gltA ) and three variable ( sca4 , ompB and ompA ) genes in five R. asembonensis DNA samples detected in cat and dog fleas in Peru. Complete gene sequences were used to conduct multi-locus sequence typing and phylogenetic analyses to assess diversity and infer relationships among strains and other reference sequences. The 17-kDa antigen gene was highly conserved across Rickettsia species. Of the variable genes ompB was the most variable, but this diversity was not captured through phylogenetics alone even when efforts were made to maximize potential diversity in terms of flea species, animal host and location. Through a combination of de novo and reference-based genome assembly we identified a 75 bp insertion in ompA that encodes a 25 aa repetitive motif found in other Rickettsia species, but not present in the original prototype strain from Kenya. R. asembonensis has only recently been shown to be a bona-fide human pathogen. As such, and compounded by a lack of available genomic information, it remains understudied. Our work directly addresses the lack of genomic information available worldwide for the study of these novel Rickettsia species and specifically contributes to our understanding of the diversity and molecular epidemiology of R. asembonensis in Peru. - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Efficacy of a spatial repellent for control of Aedes-borne virus transmission: A cluster-randomized trial in Iquitos, Peru(National Academy of Sciences, 2022-06-28)Over half the world’s population is at risk for viruses transmitted by Aedes mosquitoes, such as dengue and Zika. The primary vector, Aedes aegypti , thrives in urban environments. Despite decades of effort, cases and geographic range of Aedes -borne viruses (ABVs) continue to expand. Rigorously proven vector control interventions that measure protective efficacy against ABV diseases are limited to Wolbachia in a single trial in Indonesia and do not include any chemical intervention. Spatial repellents, a new option for efficient deployment, are designed to decrease human exposure to ABVs by releasing active ingredients into the air that disrupt mosquito–human contact. A parallel, cluster-randomized controlled trial was conducted in Iquitos, Peru, to quantify the impact of a transfluthrin-based spatial repellent on human ABV infection. From 2,907 households across 26 clusters (13 per arm), 1,578 participants were assessed for seroconversion (primary endpoint) by survival analysis. Incidence of acute disease was calculated among 16,683 participants (secondary endpoint). Adult mosquito collections were conducted to compare Ae. aegypti abundance, blood-fed rate, and parity status through mixed-effect difference-in-difference analyses. The spatial repellent significantly reduced ABV infection by 34.1% (one-sided 95% CI lower limit, 6.9%; one-sided P value = 0.0236, z = 1.98). Aedes aegypti abundance and blood-fed rates were significantly reduced by 28.6 (95% CI 24.1%, ∞); z = −9.11) and 12.4% (95% CI 4.2%, ∞); z = −2.43), respectively. Our trial provides conclusive statistical evidence from an appropriately powered, preplanned cluster-randomized controlled clinical trial of the impact of a chemical intervention, in this case a spatial repellent, to reduce the risk of ABV transmission compared to a placebo.