Effects of water quality, sanitation, handwashing, and nutritional interventions on diarrhoea and child growth in rural Bangladesh: a cluster randomised controlled trial
Stephen P Luby, Mahbubur Rahman, Benjamin F Arnold, Leanne Unicomb, Sania Ashraf, Peter J Winch, Christine P Stewart, Farzana Begum, Faruqe Hussain, Jade Benjamin-Chung, Elli Leontsini, Abu M Naser, Sarker M Parvez, Alan E Hubbard, Audrie Lin, Fosiul A Nizame, Kaniz Jannat, Ayse Ercumen, Pavani K Ram, Kishor K Das, Jaynal Abedin, Thomas F Clasen, Kathryn G Dewey, Lia C Fernald, Clair Null, Tahmeed Ahmed, John M Colford Jr
Lancet Global Health · 2018 · DOI: 10.1016/S2214-109X(17)30490-4
Countries: Bangladesh
What Was Studied
This cluster-randomised controlled trial (WASH Benefits Bangladesh) enrolled 5,551 pregnant women across 720 geographically-matched clusters in rural Gazipur, Kishoreganj, Mymensingh, and Tangail districts, Bangladesh, between May 2012 and July 2013. Clusters were randomised to one of seven groups: control, chlorinated drinking water, upgraded sanitation (double-pit pour-flush latrines), handwashing promotion, combined water+sanitation+handwashing (WSH), nutritional counselling plus lipid-based nutrient supplements (LNS), or combined WSH+nutrition. Trained community promoters delivered household-level interventions over roughly two years. Primary outcomes were caregiver-reported 7-day diarrhoea prevalence (assessed across two follow-up rounds in up to 14,425 children under age 3) and length-for-age Z score (LAZ) at 2-year follow-up in 4,584 index children.
What They Found
Compared with 5.7% diarrhoea prevalence in the control group, prevalence was significantly lower in children receiving sanitation (3.5%; prevalence ratio 0.61, 95% CI 0.46-0.81), handwashing (3.5%; PR 0.60, 0.45-0.80), nutrition (3.5%; PR 0.64, 0.49-0.85), and combined WSH+nutrition (3.5%; PR 0.62, 0.47-0.81) -- but chlorinated drinking water alone had no significant effect (4.9%; PR 0.89, 0.70-1.13). Combining water, sanitation, and handwashing (WSH) produced no additional reduction beyond single sanitation or handwashing interventions (PR 0.69, 0.53-0.90). For growth, only nutrition-inclusive arms improved length-for-age Z score (LAZ): +0.25 (95% CI 0.15-0.36) for nutrition alone and +0.13 (0.02-0.24) for combined WSH+nutrition versus control; WASH interventions alone or combined had no effect on growth. Children in the combined WSH+nutrition group had 38% lower mortality than controls (risk difference -1.9%, 95% CI -3.6 to -0.1; p=0.037).
What This Means for Nepal
For Nepal, where under-5 diarrhoea prevalence stands at 10% and 28% of episodes still receive no treatment despite the country's 2019 Open-Defecation-Free designation, this trial's central lesson -- that combining water, sanitation, and handwashing components added no extra benefit over single interventions -- has direct implications for MoHP's WASH investment strategy: rather than funding costly bundled packages, programmes may achieve larger population-level diarrhoea reductions by scaling a single high-uptake intervention, such as handwashing promotion delivered through Nepal's ~50,400-strong FCHV network, to more households. Second, because only nutrition-inclusive arms improved child growth (+0.25 LAZ) while WASH alone did not, Nepal's persistent 25% under-5 stunting rate will not be resolved by WASH investment alone; MoHP and provincial health directorates implementing the Nepal Health Sector Strategic Plan (NHSSP) 2023-2030 should pair FCHV-delivered nutrition counselling and lipid-based supplement pilots with WASH programming rather than assume the latter will independently move growth outcomes.
Contextualisation
Nepal has achieved near-universal basic water access (98%) and rising basic sanitation coverage (73%, up from 40% in 2011), and was declared South Asia's first Open-Defecation-Free nation in 2019 -- yet NDHS 2022 still recorded 7% open defecation and 10% under-5 diarrhoea prevalence, with only 48% of episodes treated with ORS. This trial's central finding -- that sanitation and handwashing each cut diarrhoea by roughly 40% but combining them added no extra benefit -- is directly relevant to how MoHP and Nepal's ~50,400 Female Community Health Volunteers (FCHVs) prioritise limited WASH resources, though Bangladesh's flat delta terrain (the standard comparator for Nepal's WASH evidence) differs meaningfully from Nepal's hill and mountain topography.