Urban Drinking Water and Health Outcomes - Early Phase Study for a Randomized Controlled Trial in Accra, Ghana

许多撒哈拉以南非洲城市努力为其居民提供安全的饮用水，这既是快速城市化的结果，也是释放资金以提高供水能力的结果。作为西非部分地区解决这一问题的本土解决方案，过去十年来发展了一种家庭手工业，出售塑料袋装的水，称为袋装水。现有证据表明，较贫穷的家庭经常购买这些水囊，至少在加纳的阿克拉，水囊中的水一般质量可以接受。然而，目前还不清楚那些以小袋形式消费相对少量的优质水的家庭是否会降低患腹泻病的风险。这些小袋子，系在顶部的角落，通常成本不到4便士（0.1加纳塞迪）的袋子含有500毫升的水，他们所包含的水来自市政管道供应系统。最初，卫生仍然是一个问题，因为袋子通常由妇女和儿童填充，很少注意污染风险。在20世纪90年代末，新的中国机器将水热封在塑料套管中，有效地创造了现代香包，目前在几个西非国家的街道上出售。过滤和化学处理过程最终也被安装到一些机器中，目前还没有研究袋装水对健康的影响，也没有研究袋装水与其他形式的家庭饮用水供应在减少疾病负担方面的相对成本效益。小袋比瓶装水便宜，因为相对于装瓶厂，小袋所需的资本投资和包装材料要低得多。一般来说，小袋水的消费量，主要消费者和水的使用方式知之甚少，虽然它往往是较贫穷的家庭购买小袋水。拟议的研究旨在调查提供补贴的小袋水使用的儿童在加纳的阿克拉腹泻的风险的可行性。研究亦会评估研究资助学券计划对儿童健康的影响的可行性。它将侧重于缺乏可靠的自来水供应的居民区。为了评估袋装水的安全性及其对此类计划的适用性，我们将测试从全市抽取的主要品牌袋装水样本的微生物水质。一小部分试点参与家庭的成员将获得代金券，使他们能够从当地水供应商那里免费或以50%的折扣获得小袋水。其他人将继续像往常一样消耗水。腹泻病将在参与家庭的儿童中进行测量。我们会利用试验研究，找出小袋代用券制度可能引起的问题，以及量度腹泻疾病的问题。透过观察接受代用券的儿童与未接受代用券的儿童在腹泻率和生长方面的差异，我们应可透过随后进行的更大规模研究，评估更多使用小袋代用券是否可预防经水传播的疾病。在这项后续研究中，提供免费和折扣的香囊水券应使我们能够了解人们如何使用香囊水，例如通过补贴来应对价格的变化。这些资料应使我们能够评估，在多大程度上，小袋水的监管或补贴的成本是合理的，可能会导致健康的好处。如果成功的话，这项研究可以表明，一个管理良好的袋装水行业是否可以作为一种临时手段，为较贫困的城市家庭提供更安全的水。这反过来又将有助于减少撒哈拉以南非洲城市的腹泻病和儿童死亡率。与其他一些供水方法不同，袋装水是撒哈拉以南非洲出现的一种现象，而不是外部强加的解决办法。

Many sub-Saharan African cities struggle to provide their residents with safe drinking-water, both as a result of rapid urbanisation and in freeing up funding to increase water supply capacity. As a home-grown solution to this problem in parts of West Africa, a cottage industry has developed over the past ten years to sell water in plastic packets, known as sachet water. Existing evidence suggests that poorer households often buy these water sachets and - at least in Accra in Ghana - the water they contain is generally of acceptable quality. However, it is unclear whether the households who consume relatively small quantities of better quality water in the form of sachets are at reduced risk of diarrhoeal disease. These small bags, tied by the corners at the top, generally cost less than 4 pence (0.1 Ghanaian cedis) for a bag containing 500ml of water and the water they contain comes from the municipal piped supply system. Initially, hygiene remained an issue, as bags were generally filled by women and children with little attention to contamination risks. In the late 1990s, new Chinese machinery that heat-sealed water in a plastic sleeve effectively created the modern sachet that is currently sold on the streets of several West African nations. Filtration and chemical treatment processes were eventually built into some machines as well.There is as yet no study of the health impact of sachet water, nor of the relative cost effectiveness of sachet water versus other forms of household drinking water provision in reducing disease burden. Sachets are cheaper than bottled water due to the substantially lower capital investment and packaging material required relative to bottling plants. Generally, little is known about the quantities of sachet water consumed, the main consumers and the ways the water is used, though it is often poorer households that purchase sachet water.The proposed study aims to investigate the feasibility of providing subsidised sachet water use to children at risk of diarrhoea in Accra, Ghana. It will also assess the feasibility of studying the impact of a subsidised voucher scheme on child health. It will focus on neighbourhoods that lack access to a reliable piped water supply. To assess the safety of sachet water and its suitability for such a programme, we will test the microbial water quality of a sample of major brands of sachets drawn from across the city. Some members of a small pilot group of participating households will be provided with vouchers that will enable them to obtain sachets from local water vendors, either for free or at a 50% discount. Others will continue to consume water as usual. Diarrhoeal disease will be measured among children in participating households. We will use the pilot study to identify any potential problems arising from the sachet voucher system and issues in measuring diarrhoeal disease.By looking at the difference in diarrhoea rates and growth between children receiving the vouchers and those who have not yet received them, we should be able to assess via a subsequent, larger study whether greater sachet use protects against water-borne disease. Supplying vouchers for both free and discounted sachet water in this follow-up study should enable us to see how people's use of sachets responds to changes in their price, for example through a subsidy. This information should enable us to assess how far the costs of sachet water regulation or subsidy are justified by the health benefits that may result. If successful, the study could show whether a well regulated sachet water industry can act as an interim means of providing poorer urban households with safer water. This in turn would help reduce diarrhoeal disease and child mortality in urban sub-Saharan Africa. Unlike some other methods of water provision, sachet water is a phenomenon that has emerged within sub-Saharan Africa rather than being an externally imposed solution.