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难以为居民提供安全饮用水，这既是快速城市化的结果，也是增加供水能力所需资金释放的结果。作为西非部分地区解决这一问题的本土方法，过去十年来，一个家庭手工业已经发展起来，出售塑料包装的水，被称为小袋水。现有证据表明，较贫穷的家庭经常购买这些水袋，而且——至少在加纳的阿克拉——它们装的水的质量通常是可以接受的。然而，目前尚不清楚的是，饮用相对少量的袋装优质水的家庭患腹泻病的风险是否降低。这些小袋子，用顶部的角系起来，通常售价不到4便士（0.1加纳塞迪），一袋装500毫升水，它们装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。上世纪90年代末，中国的新机器将水热封在一个塑料套筒里，有效地制造出了目前在几个西非国家街头出售的现代香囊。过滤和化学处理过程最终也被安装到一些机器中。目前还没有研究小袋水对健康的影响，也没有研究小袋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。小袋水比瓶装水便宜，因为相对于装瓶厂，小袋水所需的资本投资和包装材料要低得多。一般来说，人们对小袋水的消费量、主要消费者和使用方式知之甚少，尽管购买小袋水的往往是较贫穷的家庭。拟议的研究旨在调查为加纳阿克拉有腹泻风险的儿童提供补贴的小袋水的可行性。政府亦会评估研究资助券计划对儿童健康的影响的可行性。它将把重点放在缺乏可靠管道供水的社区。为了评估小袋水的安全性及其是否适合这项计划，我们将测试从全市各地抽取的主要品牌小袋水样本的微生物水质。参与试验的一小部分家庭成员将获得代金券，使他们能够免费或以五折的价格从当地的水摊贩那里获得水包。其他人将继续像往常一样用水。将测量参与家庭中儿童的腹泻病情况。我们将利用这项试点研究确定小袋代金券制度产生的任何潜在问题以及衡量腹泻病方面的问题。通过观察接受代金券的儿童和尚未接受代金券的儿童在腹泻率和生长方面的差异，我们应该能够通过随后的更大规模研究来评估，更多地使用小袋是否能预防水传播疾病。在后续研究中提供免费和折扣小袋水的代金券，可以让我们看到人们对小袋水的使用是如何对价格变化做出反应的，比如通过补贴。这一信息应使我们能够评估可能产生的健康效益在多大程度上证明小袋水管制或补贴的成本是合理的。如果取得成功，这项研究可能表明，一个管理良好的小袋水行业是否可以作为一种临时手段，为较贫穷的城市家庭提供更安全的水。这反过来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地区出现的一种现象，而不是外部强加的解决方案。

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.