Health benefits from improvements in water supply and sanitation : survey and analysis of the literature on selected diseases

The most notable achievement was in the area of rural water supply, where coverage increased from 32% in 1980 to 42% in 1985. This report reviews 144 English-language studies on the impact of improved water supply and sanitation facilities on six diseases: diarrheal diseases, ascariasis, dracunculiasis (guinea worm), hookworm, schistosomiasis, and trachoma. The review indicated that the impact has been significant. Median reductions in incidence were 78% for guinea worm, 77% for schistosomiasis, 29% for ascariasis, 27% for trachoma, and 26% for diarrhea. All studies of hookworm were flawed with one exception, which found a 4% reduction in incidence. The substantial impact of water and sanitation on child survival is also evident, with the 6 better studies indicating a 55% median reduction in overall child mortality, though none of these studies, unfortunately, specifically addressed diarrheal disease. The report also points out that water and sanitation often has an even greater impact on the reduction of disease severity than it does on disease incidence. Several factors important for maximizing the impact of water and sanitation projects are noted in conclusion: close proximity of water supply to homes, hygiene education to encourage more water use, culturally appropriate sanitation facilities, the use of facilities during critical seasonal transmission periods (i.e., for guinea worm), the greater importance of safe excreta disposal and proper water use over drinking water quality, and the installation of sanitation facilities in conjunction with water facilities when fecal-related diseases are prevalent.