Solar disinfection of drinking water and diarrhoea in Maasai children: a controlled field trial

Solar radiation reduces the bacterial content of water, and may therefore offer a method for disinfection of drinking water that requires few resources and no expertise. We distributed plastic water bottles to 206 Maasai children aged 5–16 years whose drinking water was contaminated with faecal coliform bacteria. Children were instructed to fill the bottle with water and leave it in full sunlight on the roof of the hut (solar group), or to keep their filled bottles indoors in the shade (control group). A Maasai-speaking fieldworker who lived in the community interviewed the mother of each child once every 2 weeks for 12 weeks. Occurrence and severity of diarrhoea was recorded at each follow-up visit. Among the 108 children in households allocated solar treatment, diarrhoea was reported in 439 of the 2-week reporting periods during the 12-week trial (average 4·1 [SD 1·2] per child). By comparison, the 98 children in the control households reported diarrhoea during 444 2-week reporting periods (average 4·5 [1·2] per child). Diarrhoea severe enough to prevent performance of duties occurred during 186 reporting periods in the solar group and during 222 periods in the control group (average 1·7 [1·2] vs 2·3 [1·4]). After adjustment for age, solar treatment of drinking water was associated with a reduction in all diarrhoea episodes (odds ratio 0·66 [0·50–0·87]) and in episodes of severe diarrhoea (0·65 [0·50–0·86]). Our findings suggest that solar disinfection of water may significantly reduce morbidity in communities with no other means of disinfection of drinking water, because of lack of resources or in the event of a disaster.