Solar disinfection of drinking water protects against cholera in children under 6 years of age

Department of Tropical Medicine and International Health, Royal College of Surgeons, Mercer Building, Dublin 2, Republic of Ireland.
Archives of Disease in Childhood (Impact Factor: 2.9). 11/2001; 85(4):293-5.
Source: PubMed


We have previously reported a reduction in risk of diarrhoeal disease in children who used solar disinfected drinking water. A cholera epidemic, occurring in an area of Kenya in which a controlled trial of solar disinfection and diarrhoeal disease in children aged under 6 had recently finished, offered an opportunity to examine the protection offered by solar disinfection against cholera.
In the original trial, all children aged under 6 in a Maasai community were randomised by household: in the solar disinfection arm, children drank water disinfected by leaving it on the roof in a clear plastic bottle, while controls drank water kept indoors. We revisited all households which had participated in the original trial.
There were 131 households in the trial area, of which 67 had been randomised to solar disinfection (a further 19 households had migrated as a result of severe drought). There was no significant difference in the risk of cholera in adults or in older children in households randomised to solar disinfection; however, there were only three cases of cholera in the 155 children aged under 6 years drinking solar disinfected water compared with 20 of 144 controls.
Results confirm the usefulness of solar disinfection in reducing risk of water borne disease in children. Point of consumption solar disinfection can be done with minimal resources, which are readily available, and may be an important first line response to cholera outbreaks. Its potential in chorine resistant cholera merits further investigation.

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Available from: Ronán Michael Conroy
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    • "Studies have demonstrated that solar radiation can inactivate a wide range of microbes (fecal indicator, waterborne pathogenic bacteria, viruses and protozoal parasites). Millions of people in developing countries have been using solar disinfection (SODIS) for the treatment of water and mitigation of outbreaks related to waterborne diseases (Conroy et al., 1996; McGuiganet al., 1998; Conroy etal., 2001; Mani, 2006; Rainey and Harding, 2005). The principles of microorganisms inactivation using solar treatment include: (1) optical inactivation (radiation in the spectrum of UVA light); (2) thermal inactivation (increases water temperature) (Wegelinet al., 1994). "

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    • "Wegerlin and Sommer (1996) developed SODIS (Solar water Disinfection) and SOPA (Solar Pasteurization) methods which are based on the synergistic effects of UV rays and heat treatment of water by infrared heat. Water disinfection using the solar disinfection (SODIS) process relies on the synergistic effect of sunlight and temperature upon bacteria (Conroy et al. 2001; Reed 2004). A great part of the research in understanding the mechanism of this process has been done using transparent plastic bottles exposed to sunlight under different operating conditions. "
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    • "Field trials have demonstrated a significant health benefits from consumption of SODIS treated water [34] [35]. The effectiveness of SODIS against cholera was also demonstrated in a Kenyan health impact assessment, where an 86% reduction cholera cases was observed in households regularly using SODIS [36]. Studies to improve the efficiency of the SODIS process using low-cost, commonly available materials have been conducted [37] [38] [39] [40]; however, the simple approach of exposing a 2 L PET bottle to full sun for a minimum of 6 hours is the most commonly promoted and practiced method. "
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    ABSTRACT: It is estimated that 884 million people lack access to improved water supplies. Many more are forced to rely on supplies that are microbiologically unsafe, resulting in a higher risk of waterborne diseases, including typhoid, hepatitis, polio, and cholera. Due to poor sanitation and lack of clean drinking water, there are around 4 billion cases of diarrhea each year resulting in 2.2 million deaths, most of these are children under five. While conventional interventions to improve water supplies are effective, there is increasing interest in household-based interventions to produce safe drinking water at an affordable cost for developing regions. Solar disinfection (SODIS) is a simple and low cost technique used to disinfect drinking water, where water is placed in transparent containers and exposed to sunlight for 6 hours. There are a number of parameters which affect the efficacy of SODIS, including the solar irradiance, the quality of the water, and the nature of the contamination. One approach to SODIS enhancement is the use of semiconductor photocatalysis to produce highly reactive species that can destroy organic pollutants and inactivate water pathogens. This paper presents a critical review concerning semiconductor photocatalysis as a potential enhancement technology for solar disinfection of water.
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