Solar Disinfection Of Water Does Not Reduce Diarrhoea In Children

Main Category: Water - Air Quality / Agriculture
Also Included In: Pediatrics / Children's Health;  GastroIntestinal / Gastroenterology
Article Date: 18 Aug 2009 - 6:00 PDT

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Despite global promotion and dissemination of technologies for solar disinfection of drinking water, a paper in the open access journal PLoS Medicine reports no evidence that such disinfection leads to fewer episodes of diarrhoea among children under age 5. Daniel Mäusezahl (Swiss Tropical Institute, University of Basel, Switzerland) and colleagues conducted a cluster-randomized controlled trial in 22 rural communities in Bolivia to evaluate the effect of solar drinking water disinfection (SODIS) on reducing diarrhoea among children under the age of 5, coinciding with a large SODIS-promotion campaign that targeted households, communities, and primary schools.

Dr. Mäusezahl and colleagues from the Universities of California, Berkeley and of San Simon, Cochabamba randomly assigned 11 communities (225 households, 376 children) to receive the intervention-a standardized, interactive SODIS promotion campaign conducted by Project Concern International (a nongovernmental organization)-and 11 communities (200 households, 349 children) to act as controls. Households in the intervention arm were trained to expose water-filled plastic bottles for at least 6 hours to sunlight using demonstrations, role play, and videos. Mothers in both arms of the trial completed a daily child health diary for a year. Almost 80% of the households self-reported using SODIS at the beginning and end of the study, although community field workers estimated that the only 32.1% of households on average used SODIS. Data collected in the child health diaries, which were completed on more than three-quarters of days in both arms of the trial, indicated that the children in the intervention arm had 3.6 episodes of diarrhea per year whereas the children in the control arm had 4.3 episodes of diarrhoea per year. The difference in diarrhoea episodes was not statistically significant despite the comprehensive promotion campaign.

The authors conclude that "We believe that clearer understandings of the discrepancy between laboratory and field results (obtained under typical environmental and cultural conditions), the role of compliance in effectiveness, and a direct comparison of SODIS to alternate drinking water treatment methods are needed before further global promotion of SODIS."

Globally, 1.8 million people die every year from diarrhoeal diseases, the vast majority of whom are children under the age of 5 years living in developing countries, say the authors. Unsafe water, sanitation, and hygiene are considered to be the most important global risk factors for diarrhoeal illnesses. SODIS is attractive because it is a simple, low-cost, environmentally sustainable point-of-use water purification method where recycled transparent plastic drinks bottles containing contaminated water are exposed to full sunlight for 6 hours. During this exposure, ultraviolet radiation from the sun, together with an increase in temperature, inactivates the disease-causing organisms in the water. Previous laboratory studies had suggested its efficacy in improving microbial quality.

In a commentary on the article, Zulfiqar Bhutta (uninvolved in the research) from The Aga Khan University, Karachi, Pakistan agrees that the negative results in this largest RCT to date of SODIS at a population level are important. But he cautions that it is "uncertain if the trial reflects a failure of the intervention as opposed to the delivery strategy itself", because "the compliance achieved with the intervention itself was a mere 32.1%, and hence the observed effect size probably reflects the overall poor coverage of the intervention." Still, he "applauds such research, as it is precisely the type of information needed to facil itate delivery of key interventions to address the Millennium Development Goals." These include the MDG 7, which aims to halve the proportions of people globally without sustainable access to safe drinking water and basic sanitation by 2015. The PLoS Medicine editors wrote in a June 2009 editorial that clean water should be recognised as a basic human right.

Funding:
The main financial support was from the National Institutes of Health (NIH), Award Number R01AI50087-01. In-kind and financial support were also provided by Project Concern International, University of San Simon, SODIS Foundation, Cochabamba, and the Swiss Tropical Institute, Basel. The sponsors had no role in the design and conduct of the study; collection, management, analysis, and interpretation of the data; or preparation, review, or approval of the manuscript.

Competing Interests:
The authors have declared that no competing interests exist.

Citation:
"Solar Drinking Water Disinfection (SODIS) to Reduce Childhood Diarrhoea in Rural Bolivia: A Cluster-Randomized, Controlled Trial."
Mäusezahl D, Christen A, Duran Pacheco G, Tellez FA, Iriarte M, et al. (2009)
PLoS Med 6(8): e1000125. doi:10.1371/journal.pmed.1000125

Source
PLoS Medicine

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