Water, sanitation and hygiene interventions to combat childhood diarrhoea in developing countries
Author(s)/Editor(s): Waddington H, Snilstveit B, White, H et al.
Publisher/Organizer: International Initiative for Impact Evaluation (3ie)
Publication date: 2009
Number of pages: 119
“This report is a synthetic review of impact evaluations examining effectiveness of water, sanitation and hygiene (WSH) interventions in reducing childhood diarrhoea.
The review has been conducted to Campbell/Cochrane Collaboration standards of systematic review, as well as employing mixed methods of data analysis to assess not only which interventions are effective, or not, but why and under what circumstances. The review provides an update of previous reviews conducted in this area, notably Fewtrell and Colford (2004).
A comprehensive search was conducted of published and unpublished materials. Studies were identified for inclusion which employed rigorous impact evaluation techniques, using experimental (randomised assignment) and quasi-experimental methods, and which evaluated the impact of water, sanitation and/or hygiene interventions on diarrhoea morbidity among children in low- and middle-income countries. 65 rigorous impact evaluations were identified for quantitative synthesis, covering 71 distinct interventions assessed across 130,000 children in 35 developing countries during the past three decades.
Each study was coded for a range of variables relating to type of intervention, effect size and precision, internal validity (relating to evaluation quality) and external validity (relating to context and behavioural mechanisms). Interventions were grouped into five categories: water supply improvements, water quality, sanitation, hygiene and multiple interventions involving a combination of water and sanitation and/or hygiene. Data were collected and synthesised on both quantitative and qualitative information presented in the evaluations.
The results challenge the notion that water quality treatment in the household (at point-of-use) and sanitation ‘software’ (hygiene) interventions are necessarily the most efficacious and sustainable interventions for promoting reduction of diarrhoea.
While point-of-use water quality interventions appear to be highly effective – and indeed, more effective than water supply or source treatment in reducing diarrhoea – much of the evidence is from trials conducted over small populations and short time periods. More evidence is needed on sustainability, as water quality interventions conducted over longer periods tend to show smaller effectiveness, while compliance rates, and therefore impact, appear to fall markedly over time.
Hygiene interventions, particularly provision of soap for hand-washing, are effective in reducing diarrhoea morbidity, and there does not appear to be evidence that compliance falls over time. The analysis suggests that sanitation ‘hardware’ interventions are also highly effective. However, relatively few studies have been conducted in this area to-date and studies are particularly needed that quantify the possible environmental spillovers from sanitation provision.”