Assessing the impact of sanitation on indicators of fecal exposure along principal transmission pathways: A systematic review.

OBJECTIVE: Fecal-oral transmission of enteric and other pathogens due to poor sanitation is a major cause of morbidity and mortality, especially in low- or middle-income settings. Few studies have investigated the impact of sanitation on indicators of transmission, a prerequisite to achieving health gains. This review attempts to summarize the literature to date. METHODS: We searched leading databases to identify studies that address the effect of sanitation on various transmission pathways including fecal pathogens or indicator bacteria in drinking water, hand contamination, sentinel toys, food, household and latrine surfaces and soil, as well as flies and observations of human feces. This also included studies that assessed the impact of fecal contamination of water supplies based on distance from sanitation facilities. We identified 29 studies that met the review's eligibility criteria. RESULTS AND CONCLUSION: Overall, the studies found little to no effect from sanitation interventions on these transmission pathways. There was no evidence of effects on water quality (source or household), hand or sentinel toy contamination, food contamination, or contamination of surfaces or soil. There is some evidence that sanitation was associated with reductions in flies and a small effect on observations of feces (Risk Difference -0.03, 95%CI -0.06 to 0.01). Studies show an inverse relationship between the distance of a water supply from a latrine and level of fecal contamination of such water supply. Future evaluations of sanitation interventions should include assessments of effects along transmission pathways in order to better understand the circumstances under which interventions may be effective at preventing disease.