Solar Water Disinfection: Randomized Intervention Trial

说明(申请人提供)：发展中国家农村和城市周边地区三分之一以上的人口无法获得不含病原体的充足或清洁饮用水。因此，水源性胃肠炎仍然是一个重大的基础设施和公共卫生问题，特别是因为有效的治疗(过滤、加氯、处理工厂)往往超出财政能力，或者用于水净化的环境资源在这些社区变得稀缺(烧水、燃烧碳基燃料)。在这方面，利用太阳光直射和太阳能加热相结合的方式对饮用水进行太阳能消毒特别有吸引力，以杀灭受污染饮用水中的水媒病原体。到目前为止，SODIS技术作为一种以家庭为基础的低成本干预措施，在低收入国家提供安全饮用水的有效性已经确立，一项大规模的推广和传播计划正在七个拉丁美洲国家进行。这项研究的主要目的是评估家庭太阳能水消毒(SODIS)在减轻农村地区5岁以下儿童胃肠道疾病负担方面的有效性，这些儿童参加了玻利维亚全国SODIS项目。我们将进行一项社区(群)随机对照试验，跟踪每个社区5岁以下儿童的队列。总共将从国家计划指定的地区中选择22个社区接受SODIS干预。将采用配对设计，首先根据社区腹泻疾病的基线发病率对社区进行排名，然后在11对连续社区中的每一对中随机分配给其中一个社区。在每个小组中，将有30名儿童(共660名)参加，并进行为期12个月的跟踪调查。有关腹泻疾病的数据将从母亲保存的发病率日记中获得，并通过每周家访进行验证。将在基线发病率调查期间收集粪便样本，并在后续期间收集儿童腹泻发作时的粪便样本。将对饮用水原水水源和SODIS设备处理后的水样进行系统的水质监测。参与儿童的母亲将在基线和试验期间就其子女在家庭和社区内的当前用水、行为和环境暴露情况接受采访。这项研究将具体评估：(1)在实验室实验和两个严格控制的第二阶段试验中建立的SODIS技术的有效性在多大程度上可以保留为有效，即在计划条件下；(2)可归因于SODIS的所有原因儿童腹泻的预防比例；(3)将计算腹泻疾病的病原体特定归因风险和SODIS的成本效益。该项目由加州大学伯克利分校组织，在美国的水干预试验方面拥有丰富的经验，并受益于瑞士巴塞尔瑞士热带研究所在公共卫生研究方面的南北合作传统。它是与圣西蒙大学市长的玻利维亚合作伙伴以及协调玻利维亚SODIS计划的Fondazion SODIS共同运作的。

DESCRIPTION (provided by applicant): More than one third of the population in rural and in peri-urban areas of developing countries have no access to sufficient or clean drinking water free of pathogens. Thus, waterborne gastroenteritis remains a major infrastructural and public health problem particularly, as effective treatment (filtration, chlorination, treatments plants) is often beyond financial means or environmental resources used for water purification (fire-boiling, burning carbon-based fuels) become scarce in those communities. In this context solar disinfection of drinking water is especially appealing using a combination of irradiation by direct sunlight and solar heating to kill the water-borne pathogens in contaminated drinking water. To date, the efficacy of the SODIS technology as a home-based, low-cost intervention to provide safe drinking water in low income countries is well established, and a large-scale promotion and dissemination program is under way in seven Latin American countries. The principal objective of this study is to evaluate the effectiveness of home-based solar water disinfection (SODIS) in reducing the burden of gastrointestinal illness in children under 5 years in rural villages participating in a country-wide Bolivian SODIS program. We will conduct a community (cluster)-randomized controlled trial following a cohort of children under age 5 in each community. Totally, 22 communities will be selected from among those districts designated by the country-program to receive the SODIS intervention. A pair-matched design will be employed where communities are first ranked according to their baseline incidence of diarrheal disease and the intervention then assigned within each of the 11 consecutive pairs of communities randomly to one of them. In each cluster, 30 children (660 in total) will be enrolled and followed up for 12 months. Data on diarrheal illness will be obtained from morbidity diaries kept by mothers and validated through weekly home visits. Stool samples will be collected during the baseline morbidity surveys and at times of a diarrheal episode in a child during follow-up. Water quality monitoring of raw water sources used for drinking water and of water samples after treatment with the SODIS device will be conducted systematically. Mothers of participating children will be interviewed at baseline and during the trial with regard to current water use, behavioral and environmental exposures of their child in the home and within the community. This study will specifically estimate: (1) how much of the efficacy of the SODIS technology established in laboratory experiments and in two tightly controlled phase-Ill trials can be retained as effectiveness, i.e., under program conditions; (2) the preventive fraction of all-cause child-diarrhea attributable to SODIS; and (3) pathogen-specific attributable risks of diarrheal illness and the cost-effectiveness of SODIS will be calculated. The project is organized by the University of California, Berkeley, with its substantial experience in water intervention trials in U.S. and it benefits from the tradition of North-South collaboration in public health research of the Swiss Tropical Institute, Basel, Switzerland. It is run jointly with the Bolivian partners at the Universidad Mayor de San Simon and the Fondazion SODIS that coordinates the Bolivian SODIS program.