Two recent cluster RCTs published in Lancet Global Health have reported on WASH (water quality, sanitation and handwashing) and nutritional interventions.  One was conducted in Bangladesh and the other in Kenya; they were both based on recruitment of pregnant woman, who were then grouped in delineated clusters based on geographical proximity. The studies were all entirely rural.
Both studies found that nutritional interventions, either singly or in combination with other wash interventions, improved child growth. The Kenyan study found no benefit for WASH interventions on reported rates of diarrhoea. However, the Bangladesh study did find a reduction of diarrhoea of about 40% in the WASH intervention groups. A follow-on study to the Bangladesh trial at one year of age found an improvement in developmental milestones across all of the intervention groups.
Probably the strongest message to come out here, is that nutritional interventions improve growth in deprived rural populations. This is consistent with most, but not all, previous literature. The discordant effects of WASH interventions on diarrhoea rates across Kenya and Bangladesh is puzzling and no convincing explanation is offered by the authors. I note, however, that the prevalence of diarrhoea was much higher in Kenya than in Bangladesh. Of course, that provides more headroom for improvement In the Kenyan setting, making the discordant results even more perplexing. One possibility, is that reported diarrhoea rates are just a very poor marker for gastrointestinal disease. Worse still, they are ‘reactive’, meaning that if people are aware that they are on the receiving end of an intervention to reduce diarrhoea rates, then they may report less diarrhoea, even if the true prevalence is unchanged. We are investigating this possibility in a study in Mwanza, Tanzania, which we are conducting in collaboration with UN-Habitat. I am not sure how to interpret these results with respect to the theory that chronic gastrointestinal infections aggrevate malnutrition by causing a chronic malabsorptive small bowel enteropathy.
It is interesting to compare these results with the effects of the sanitary revolution in Europe and North America over a century ago. Here again, water and sanitation had modest and inconsistent effects on childhood diarrhoea, but with much more dramatic effects on typhoid and cholera. Taken in the round these recent results reported in Lancet Global Health are consistent with historical data.
— Richard Lilford, CLAHRC WM Director
- Luby SP, Rahman M, Arnold BF, et al. Effects of water quality, sanitation, handwashing, and nutritional interventions on diarrhoea and child growth in rural Bangladesh: a cluster randomised controlled trial. Lancet Glob Health. 2018; 6: e302-15.
- Null C, Stewart CP, Pickering AJ, et al. Effects of water quality, sanitation, handwashing, and nutritional interventions on diarrhoea and child growth in rural Kenya: a cluster-randomised controlled trial. Lancet Glob Health. 2018; 6: e316-29.
- Tofail F, Fernald LCH, Das KK, et al. Effects of water quality, sanitation, hand washing, and nutritional interventions on child development in rural Bangladesh (WASH Benefits Bangladesh): a cluster-randomised controlled trial. Lancet Child Adolesc Health. 2018; 2: 255-68.
- Clasen T, Boisson S, Routray P, Torondel B, Bell M, Cumming O, et al. Effectiveness of a rural sanitation programme on diarrhoea, soil-transmitted helminth infection, and child malnutrition in Odisha, India: a cluster-randomised trial. Lancet Glob Health. 2014; 2(11): e645-53.
- Szreter S. The Population Health Approach in Historical Perspective. Am J Public Health. 2003; 93(3): 421-31.