Thanks to USAID’s Sanitation/Water/Env Health News Service service I get emails with a list of new abstracts every few days. Results from a new Solar Disinfection (SODIS) randomized controlled study came to my inbox today. This study, a collaborative effort between researchers in Bolivia, Switzerland, and the US (UC Berkley), sought to investigate the health impacts from a SODIS intervention through a cluster-randomized controlled study.
PLoS Medicine – August 2009 | Volume 6 | Issue 8 | e1000125
Solar Drinking Water Disinfection (SODIS) to Reduce Childhood Diarrhoea in Rural Bolivia: A Cluster-Randomized, Controlled Trial, Daniel Mausezah, Andri Christen, Gonzalo Duran Pacheco, Fidel Alvarez Tellez, Mercedes Iriarte Maria E. Zapata, Myriam Cevallos, Jan Hattendorf, Monica Daigl Cattaneo, Benjamin Arnold, Thomas A. Smith, John M. Colford Jr
Theoretically, SODIS can really have profound impacts on biological contaminants but no few large-scale rigorous studies have shown that it actually works in the field. Some of the common challenges include behavior change and proper use of the technology. It takes much more than a good technology to impact diarrhea prevalence and this study aimed to find out what could be achieved.
In the end the researchers found no statistically significant impact on diarrhea prevalence from the SODIS user group. Although this sounds depressing, there are some lessons that can be learned from this and applied to a subsequent attempt.
1. Study Design – Zulfiqar Bhutta, from the Aga Khan University, suggested in a follow up “Perspective” article that the study was designed to detect larger changes in diarrhea prevalence and the researchers may have been better off with a stepped wedge design. I am not sure what the best design would be (as I have not looked into this in depth) but if they expected lower prevalence reduction rates (which could still be important) I’ll bet the study design would have differed.
2. Focus on Behavior Change -Despite the intense software components to this study (conducted by an NGO Project Concern International) only ~30% of the SODIS group complied with the SODIS method. It would be interesting to learn more about why people failed to use the SODIS method and whether changes can be made to the education/software aspects of the project to improve uptake.
The full text of this article can be found here.
I don’t agree with your statement that “no rigorous studies have shown that it actually works in the field”. There are several rigorous studies which showed a positive impact of SODIS in diarrhea reduction (16-40%), as well as a drastically reduced risk for cholera (88% reduction).
You may want to check out for example the comprehensive meta-analsis of water quality interventions included in the Cochrane Library:
doi.wiley.com/10.1002/ebch.122
I think this new study highlights more the failure of the implementation efforts (given the intensive campaign, 32% user rate is fairly poor – and may be even lower in reality) rather than a failure of the method…
Best regards,
Frank