Water, sanitation and hygiene in developing countries: interventions and diarrhoea--a review.

We conducted a search to identify all English language papers (published between 1 January 1985 and 26 June 2003) with evidence on the effectiveness of water, sanitation and hygiene interventions in developing countries, in which diarrhoea morbidity in non-outbreak conditions was reported. A total of 39 studies were identified as relevant after an initial review of over 2000 titles. Data were extracted and, where possible, combined using meta-analysis to provide a summary estimate of the effectiveness of specific interventions, including water supply and water treatment. Most of the interventions (including multiple interventions, hygiene and water quality) were found to significantly reduce the levels of diarrhoeal illness, with the greatest impact being seen for hygiene and household treatment interventions (after removal of studies classed as poor quality). Sanitation interventions could not be assessed as only a single study suitable for meta-analysis was identified.