Understanding the mechanisms of transmission of human leptospirosis in slums settlements in Salvador, Brazil

了解巴西萨尔瓦多贫民窟中人类钩端螺旋体病的传播机制

• 批准号: 2665161
• 金额: --
• 依托单位: Lancaster University
• 依托单位国家: 英国
• 项目类别: Studentship
• 财政年份: 2021
• 资助国家: 英国
• 起止时间: 2021 至 无数据
• 项目状态: 未结题
• 来源: https://gtr.ukri.org/projects?ref=studentship-2665161
• 关键词: Understanding; mechanisms; transmission; human; leptospirosis

Global health needLeptospirosis, a spirochetal zoonosis, has emerged as an important health problem as slum settlements have expanded rapidly worldwide and created conditions for rat-borne transmission. In Brazil, 12,000 individuals are annually infected with leptospirosis, with a death rate of about 12%. In the city of Salvador, Brazil, where transmission mostly occurs in peridomestic environments, the government-led expansion of closed sewer networks has resulted in a significant decrease of infection rates for leptospirosis. However, due to political neglect and the uncontrolled expansions of slums, construction of conventional governmentally led closed sewer systems (GOV-INT) is increasingly problematic. To address this issue, innovative and more economical methods that require of community residents involvement (COM-INT) have emerged as suitable alternatives to improve sanitation in slum settlements. However, assessing the real impact of sanitation intervention, such as GOV-INT and COM-INT, is problematic because of methodological issues due to confounding factors and difficulties with randomization of the population to obtain large enough large sample sizes.Current knowledge gapsTo the best of our knowledge, no study has been carried out to assess the potentially positive effects of COM-INT on the reduction of leptospirosis risk. Based on preliminary descriptive statistics from an ongoing study in Salvador, to which this project directly contributes, it has been conjectured that GOV-INT and COM-IN are equally effective in the reduction of Leptospirosis infections. In this context, the use of spatio-temporal statistical methods are crucial in order to infer the actual impact of COM-INT by taking account of both measured and unmeasured risk factors of Leptospirosis infection. Study aims1. Determine the mechanisms by which COM-INT and GOV-INT reduce direct human contact with sewage and environmental pathogen load in urban slums.2. Determine the contribution of COM-INT and GOV-INT on a decline in severe disease incidence in a large urban center.Study design/methodologyAs part of a Wellcome-Trust project, this study will be split into the following two parts (each referring to the above aims in turn)1. The main cause of Leptospira infection is exposure to contaminated sewage and run-off. Hence, to pursue the first study aim, statistical methods that combine information from environmental reservoirs and resident's movement will be fitted to data from an ongoing study in the community of Marechal Rodon in Salvador, Brazil. This study site consists of 9 areas, 3 with GOV-INT, 3 with COM-INT and 3 with no intervention. A total of 2,582 soils samples will be collected and tested for Leptospira DNA, before and after the interventions. These data will be integrated with human mobility data collected on 150 individuals using multifunctional sensor nodes to quantity the exposure to contamination sources2. A secondary spatio-temporal geostatistical analysis will be conducted to assess the effectiveness of COM-INT and GOV-INT, using data collected since 1996 from a hospital-based surveillance for leptospirosis that covers the population of Salvador since. To account for confounding effects, information on socio-economic and environmental factors will also be incorporated into the spatio-temporal model.

全球卫生需求 钩端螺旋体病是一种螺旋体人畜共患病，随着贫民窟定居点在世界范围内迅速扩张并为鼠传传播创造了条件，钩端螺旋体病已成为一个重要的健康问题。在巴西，每年有 12,000 人感染钩端螺旋体病，死亡率约为 12%。在巴西萨尔瓦多市，传播主要发生在家庭周围环境，政府主导的封闭式下水道网络的扩建导致钩端螺旋体病的感染率显着下降。然而，由于政治忽视和贫民窟不受控制的扩张，传统的政府主导的封闭式下水道系统（GOV-INT）的建设越来越成问题。为了解决这个问题，需要社区居民参与的创新且更经济的方法（COM-INT）已经出现，作为改善贫民窟住区卫生条件的合适替代方案。然而，评估 GOV-INT 和 COM-INT 等卫生干预措施的实际影响是有问题的，因为混杂因素导致方法学问题，并且难以对人群进行随机化以获得足够大的样本量。目前的知识差距据我们所知，尚未开展任何研究来评估 COM-INT 对降低钩端螺旋体病风险的潜在积极影响。根据萨尔瓦多正在进行的一项研究（该项目直接参与该研究）的初步描述性统计数据，推测 GOV-INT 和 COM-IN 在减少钩端螺旋体病感染方面同样有效。在这种情况下，时空统计方法的使用至关重要，以便通过考虑钩端螺旋体病感染的测量和未测量危险因素来推断 COM-INT 的实际影响。研究目的 1．确定COM-INT 和GOV-INT 减少人类与城市贫民窟污水和环境病原体负荷直接接触的机制。2．确定 COM-INT 和 GOV-INT 对大型城市中心严重疾病发病率下降的贡献。研究设计/方法作为 Wellcome-Trust 项目的一部分，本研究将分为以下两个部分（每个部分依次参考上述目标）1。钩端螺旋体感染的主要原因是接触受污染的污水和径流。因此，为了实现第一个研究目标，结合环境水库和居民移动信息的统计方法将适用于巴西萨尔瓦多 Marechal Rodon 社区正在进行的研究数据。该研究中心由 9 个区域组成，其中 3 个有 GOV-INT，3 个有 COM-INT，3 个无干预。在干预之前和之后，将收集总共 2,582 个土壤样本并进行钩端螺旋体 DNA 检测。这些数据将与使用多功能传感器节点收集的 150 个人的人员流动数据相结合，以量化污染源暴露情况2。将使用自 1996 年以来覆盖萨尔瓦多人口的医院钩端螺旋体病监测收集的数据，进行二次时空地统计分析，以评估 COM-INT 和 GOV-INT 的有效性。为了考虑混杂效应，有关社会经济和环境因素的信息也将被纳入时空模型中。