Effects of improved water supply and sanitation on ascariasis, diarrhoea, dracunculiasis, hookworm infection, schistosomiasis, and trachoma

Improvements in water quality and sanitation and associated improvements in the health of the recipient populations have been major undertakings of international bodies for many years. A total of 144 reports of improvement efforts are reviewed and analyzed to assess the impact of intervention efforts on the parasitic diseases ascariasis (Ascaris lumbricoides), dracunculiasis (Dracunculus medinensis), hookworm infection (Ancylostoma duodenale, Necator americanus), schistosomiasis (Schistosoma hematobium, S. mansoni), trachoma (Chlamydia trachomatis), and diarrheal diseases. Varying results were noted in many of the studies. When the data were pooled and reconsidered, evidence of improvements effectuated in one or more of the components of water supply and sanitation was provided by the substantial reduction in the incidence and severity of these diseases. The impact on the incidence of hookworm disease was negligible. The benefits of antibiotic and chemotherapeutics were heightened by water and sanitary system improvements. In addition, these changes helped prevent the incidence of the diseases from returning to pretreatment levels. Based on this analysis, several summary recommendations are outlined. Safe excreta disposal and proper use of water resources should be given greater attention; water and sanitation facilities should be installed simultaneously in areas of fecal-related disease; accessibility of water sources to the home is essential; sanitation facilities should meet cultural needs; educational programs related to the proper use and maintenance of these systems should be developed and provided; and water and sanitation programs should complement clinical improvement programs. Recommendations for further study are suggested, and an extensive bibliography is appended. (Consumer Summary produced by Reliance Medical Information, Inc.)
A total of 144 studies were analysed to examine the impact of improved water supply and sanitation facilities on ascariasis, diarrhoea, dracunculiasis, hookworm infection, schistosomiasis, and trachoma. These disease were selected because they are widespread and illustrate the variety of mechanisms through which improved water and sanitation can protect people. Disease-specific median reduction levels were calculated for all studies, and separately for the more methodologically rigorous ones. For the latter studies, the median reduction in morbidity for diarrhoea, trachoma, and ascariasis induced by water supplies and/or sanitation was 26%, 27%, and 29%, respectively; the median reduction for schistosomiasis and dracunculiasis was higher, at 77% and 78%, respectively. All studies of hookworm infection were flawed apart from one, which reported a 4% reduction in incidence. For hookworm infection, ascariasis, and schistosomiasis, the reduction in disease severity, as measured in egg counts, was greater than that in incidence or prevalence. Child mortality fell by 55%, which suggests that water and sanitation have a substantial impact on child survival. Water for personal and domestic hygiene was important in reducing the rates of ascariasis, diarrhoea, schistosomiasis, and trachoma. Sanitation facilities decreased diarrhoea morbidity and mortality and the severity of hookworm infection. Better water quality reduced the incidence of dracunculiasis, but its role in diarrhoeal disease control was less important than that of sanitation and hygiene.
Introduction Water and sanitation have been the subjects of considerable recent attention as a result of the declaration by the United Nations General Assembly that the 1980s were the International [...]