Seven trials, seven question marks
Authors: Wolf-Peter Schmidt
Journal: The Lancet Global Health (2015)

Biological plausibility suggests that sanitation, the safe disposal of human excreta, might reduce the risk of infectious diseases as diverse as diarrhoea, schistosomiasis, soil-transmitted helminths, trachoma, and filariasis.1Mara D Lane J Scott B Trouba D Sanitation and health.PLoS Med. 2010; 7: e1000363Crossref PubMed Scopus (291) Google Scholar Until 2013, only one randomised controlled sanitation trial had been reported (into trachoma, with equivocal results).2Emerson PM Lindsay SW Alexander N et al.Role of flies and provision of latrines in trachoma control: cluster-randomised controlled trial.Lancet. 2004; 363: 1093-1098Summary Full Text Full Text PDF PubMed Scopus (173) Google Scholar As a colleague pointed out, randomised trials into improved sanitation are like London buses. One waits for ages, and then several come along at once.3Cameron L Shah M Olivia S Impact evaluation of a large-scale rural sanitation project in Indonesia. Policy research working paper 6360. The World Bank Sustainable Development Network Water and Sanitation Program, Washington2013Crossref Google Scholar, 4Clasen T Boisson S Routray P 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: e645-e653Summary Full Text Full Text PDF Scopus (333) Google Scholar, 5Hammer J Spears D Village sanitation externalities and children's human capital: evidence from a randomized experiment by the Maharashtra government. Policy research working paper 6580. The World Bank Sustainable Development Network Water and Sanitation Program, Washington2013Crossref Google Scholar, 6Patil SR Arnold BF Salvatore AL et al.The effect of India's total sanitation campaign on defecation behaviors and child health in rural Madhya Pradesh: a cluster randomized controlled trial.PLoS Med. 2014; 11: e1001709Crossref PubMed Scopus (276) Google Scholar, 7Briceno B Coville A Martinez S Promoting handwashing and sanitation: evidence from a large-scale randomized trial in rural Tanzania. Policy Research Working Paper 7164. The World Bank Group, Water Global Practice Group and Development Research Group Impact Evaluation Team, Washington2015Crossref Google Scholar The study by Amy Pickering and colleagues8Pickering AJ Djebbari H Lopez C Coulibaly M Alzua ML Effect of a community-led sanitation intervention on child diarrhoea and child growth in rural Mali: a cluster-randomised controlled trial.Lancet Glob Health. 2015; 3: e701-e711Summary Full Text Full Text PDF Scopus (220) Google Scholar in this issue of The Lancet Global Health is the sixth sanitation trial published in the past 3 years, exploring the effect of community-led total sanitation on child diarrhoea prevalence and growth in rural Mali. A key issue in public health intervention trials is adherence to the intervention. If an intervention does not achieve a reasonable change in sanitation coverage and use then there is little point in measuring the health effects. This aspect might distinguish the Mali trial8Pickering AJ Djebbari H Lopez C Coulibaly M Alzua ML Effect of a community-led sanitation intervention on child diarrhoea and child growth in rural Mali: a cluster-randomised controlled trial.Lancet Glob Health. 2015; 3: e701-e711Summary Full Text Full Text PDF Scopus (220) Google Scholar from the other trials. The sanitation trial in Indonesia achieved an increase in household sanitation coverage from just 60% to 64%.3Cameron L Shah M Olivia S Impact evaluation of a large-scale rural sanitation project in Indonesia. Policy research working paper 6360. The World Bank Sustainable Development Network Water and Sanitation Program, Washington2013Crossref Google Scholar The trial in Maharashtra, India, explored the effect of an intervention that increased coverage from perhaps 16% to 24%, an 8% difference.5Hammer J Spears D Village sanitation externalities and children's human capital: evidence from a randomized experiment by the Maharashtra government. Policy research working paper 6580. The World Bank Sustainable Development Network Water and Sanitation Program, Washington2013Crossref Google Scholar Similarly, access to any form of latrine increased from just 57% to 65% in the Tanzania trial.7Briceno B Coville A Martinez S Promoting handwashing and sanitation: evidence from a large-scale randomized trial in rural Tanzania. Policy Research Working Paper 7164. The World Bank Group, Water Global Practice Group and Development Research Group Impact Evaluation Team, Washington2015Crossref Google Scholar A 19% increase in latrine ownership was achieved in the trial in Madya Pradesh, India (from 22% to 41%),6Patil SR Arnold BF Salvatore AL et al.The effect of India's total sanitation campaign on defecation behaviors and child health in rural Madhya Pradesh: a cluster randomized controlled trial.PLoS Med. 2014; 11: e1001709Crossref PubMed Scopus (276) Google Scholar a figure that was exceeded only by the trial in Orissa (from 9% to 63%).4Clasen T Boisson S Routray P 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: e645-e653Summary Full Text Full Text PDF Scopus (333) Google Scholar However, in the Orissa trial,4Clasen T Boisson S Routray P 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: e645-e653Summary Full Text Full Text PDF Scopus (333) Google Scholar nearly half of the constructed latrines were not functional 1 year after the intervention ended. Furthermore, evidence shows that in all three Indian sites, use of newly constructed latrines was low and open defecation continued, largely unabated. None of the early trials showed any effect on health, except for the one in Maharashtra5Hammer J Spears D Village sanitation externalities and children's human capital: evidence from a randomized experiment by the Maharashtra government. Policy research working paper 6580. The World Bank Sustainable Development Network Water and Sanitation Program, Washington2013Crossref Google Scholar that suggested an improvement in child growth. In view of the low sanitation coverage achieved, this finding is implausible and might have been due to chance. Pickering and colleagues8Pickering AJ Djebbari H Lopez C Coulibaly M Alzua ML Effect of a community-led sanitation intervention on child diarrhoea and child growth in rural Mali: a cluster-randomised controlled trial.Lancet Glob Health. 2015; 3: e701-e711Summary Full Text Full Text PDF Scopus (220) Google Scholar report an increase in private latrine ownership from 35% to 65%, access to any latrine was improved from about 66% to 90%, and self-reported open defecation seemed to decrease to about 10%. Their intervention seems to have been well accepted by the study population,8Pickering AJ Djebbari H Lopez C Coulibaly M Alzua ML Effect of a community-led sanitation intervention on child diarrhoea and child growth in rural Mali: a cluster-randomised controlled trial.Lancet Glob Health. 2015; 3: e701-e711Summary Full Text Full Text PDF Scopus (220) Google Scholar even though the quality of the latrines was probably, on average, inferior to the pour-flush latrines with water seal constructed at the Indian sites.5Hammer J Spears D Village sanitation externalities and children's human capital: evidence from a randomized experiment by the Maharashtra government. Policy research working paper 6580. The World Bank Sustainable Development Network Water and Sanitation Program, Washington2013Crossref Google Scholar Sanitation is likely to be most effective if most of a neighbourhood or village practise it.9Cairncross S Blumenthal U Kolsky P Moraes L Tayeh A The public and domestic domains in the transmission of disease.Trop Med Int Health. 1996; 1: 27-34Crossref PubMed Scopus (157) Google Scholar At low or intermediate coverage, open defecation by remaining households could keep environmental exposure to pathogens fairly constant, even for people using a latrine. Increases in sanitation coverage from about 60% to 90% (as in Mali8Pickering AJ Djebbari H Lopez C Coulibaly M Alzua ML Effect of a community-led sanitation intervention on child diarrhoea and child growth in rural Mali: a cluster-randomised controlled trial.Lancet Glob Health. 2015; 3: e701-e711Summary Full Text Full Text PDF Scopus (220) Google Scholar) might therefore have a greater potential to improve a population's health than increasing sanitation coverage from about 10% to 40% (as in the Orissa4Clasen T Boisson S Routray P 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: e645-e653Summary Full Text Full Text PDF Scopus (333) Google Scholar and Madya Pradesh6Patil SR Arnold BF Salvatore AL et al.The effect of India's total sanitation campaign on defecation behaviors and child health in rural Madhya Pradesh: a cluster randomized controlled trial.PLoS Med. 2014; 11: e1001709Crossref PubMed Scopus (276) Google Scholar trials). Disappointingly, no effect on the primary study outcome, the prevalence of diarrhoea in children younger than 5 years, was noted by Pickering and colleagues in Mali.8Pickering AJ Djebbari H Lopez C Coulibaly M Alzua ML Effect of a community-led sanitation intervention on child diarrhoea and child growth in rural Mali: a cluster-randomised controlled trial.Lancet Glob Health. 2015; 3: e701-e711Summary Full Text Full Text PDF Scopus (220) Google Scholar Instead the intervention was associated with a reduction in stunting. As a secondary outcome, this finding cannot be readily interpreted as an intervention effect. However, it also cannot be dismissed as biologically implausible, as was the case in the Maharashtra trial.5Hammer J Spears D Village sanitation externalities and children's human capital: evidence from a randomized experiment by the Maharashtra government. Policy research working paper 6580. The World Bank Sustainable Development Network Water and Sanitation Program, Washington2013Crossref Google Scholar Irrespective of whether the modestly funded intervention in Mali improved health, it substantially improved sanitation access and the daily life of a poor rural population with a high demand for sanitation, as evidenced by the high pre-intervention latrine coverage. Compared with, for example, distribution of vitamin A tablets, improving sanitation is a worthy goal in itself independent of health effects.10Schmidt WP The elusive effect of water and sanitation on the global burden of disease.Trop Med Int Health. 2014; 19: 522-527Crossref PubMed Scopus (70) Google Scholar By contrast, the trials in India5Hammer J Spears D Village sanitation externalities and children's human capital: evidence from a randomized experiment by the Maharashtra government. Policy research working paper 6580. The World Bank Sustainable Development Network Water and Sanitation Program, Washington2013Crossref Google Scholar, 6Patil SR Arnold BF Salvatore AL et al.The effect of India's total sanitation campaign on defecation behaviors and child health in rural Madhya Pradesh: a cluster randomized controlled trial.PLoS Med. 2014; 11: e1001709Crossref PubMed Scopus (276) Google Scholar show that if most of the target population has no demand for sanitation then even a well-funded campaign will not succeed, and to study health effects will be pointless. The reasons for India's traditionally low demand for sanitation are complex, probably including cultural, religious, caste, and gender issues. The Indian Government's ongoing attempts to force sanitation changes by offering increasingly generous subsidies alongside modest demand creation activities have been criticised.11WaterAidFeeling the pulse: a study of the total sanitation campaign in five states. WaterAid India, New Delhi2008Google Scholar Alternative approaches have so far only shown promise on a small scale. All seven sanitation trials2Emerson PM Lindsay SW Alexander N et al.Role of flies and provision of latrines in trachoma control: cluster-randomised controlled trial.Lancet. 2004; 363: 1093-1098Summary Full Text Full Text PDF PubMed Scopus (173) Google Scholar, 3Cameron L Shah M Olivia S Impact evaluation of a large-scale rural sanitation project in Indonesia. Policy research working paper 6360. The World Bank Sustainable Development Network Water and Sanitation Program, Washington2013Crossref Google Scholar, 4Clasen T Boisson S Routray P 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: e645-e653Summary Full Text Full Text PDF Scopus (333) Google Scholar, 5Hammer J Spears D Village sanitation externalities and children's human capital: evidence from a randomized experiment by the Maharashtra government. Policy research working paper 6580. The World Bank Sustainable Development Network Water and Sanitation Program, Washington2013Crossref Google Scholar, 6Patil SR Arnold BF Salvatore AL et al.The effect of India's total sanitation campaign on defecation behaviors and child health in rural Madhya Pradesh: a cluster randomized controlled trial.PLoS Med. 2014; 11: e1001709Crossref PubMed Scopus (276) Google Scholar, 7Briceno B Coville A Martinez S Promoting handwashing and sanitation: evidence from a large-scale randomized trial in rural Tanzania. Policy Research Working Paper 7164. The World Bank Group, Water Global Practice Group and Development Research Group Impact Evaluation Team, Washington2015Crossref Google Scholar, 8Pickering AJ Djebbari H Lopez C Coulibaly M Alzua ML Effect of a community-led sanitation intervention on child diarrhoea and child growth in rural Mali: a cluster-randomised controlled trial.Lancet Glob Health. 2015; 3: e701-e711Summary Full Text Full Text PDF Scopus (220) Google Scholar published so far might underestimate the true health effect of sanitation because they were undertaken in rural villages, whereas sanitation interventions could be more effective in dense urban slums. Completing a trial in this setting, however, would be difficult. Additionally, the timeline to implement and assess the interventions might have been unrealistically short to achieve a health effect. Improving sanitation takes years rather than months, but there are clear ethical and logistical barriers to undertaking longer-term trials.10Schmidt WP The elusive effect of water and sanitation on the global burden of disease.Trop Med Int Health. 2014; 19: 522-527Crossref PubMed Scopus (70) Google Scholar Therefore, the study by Pickering and colleagues8Pickering AJ Djebbari H Lopez C Coulibaly M Alzua ML Effect of a community-led sanitation intervention on child diarrhoea and child growth in rural Mali: a cluster-randomised controlled trial.Lancet Glob Health. 2015; 3: e701-e711Summary Full Text Full Text PDF Scopus (220) Google Scholar might be as good as it gets, and their results provide much needed encouragement in this important area of public health. Additional evidence would be desirable, but might not be achieved.10Schmidt WP The elusive effect of water and sanitation on the global burden of disease.Trop Med Int Health. 2014; 19: 522-527Crossref PubMed Scopus (70) Google Scholar I declare no competing interests. Effect of a community-led sanitation intervention on child diarrhoea and child growth in rural Mali: a cluster-randomised controlled trialIn villages that received a behavioural sanitation intervention with no monetary subsidies, diarrhoeal prevalence remained similar to control villages. However, access to toilets substantially increased and child growth improved, particularly in children <2 years. CLTS might have prevented growth faltering through pathways other than reducing diarrhoea. Full-Text PDF Open Access