Do Sanitation Improvements Reduce Fecal Contamination of Water, Hands, Food, Soil, and Flies? Evidence from a Cluster-Randomized Controlled Trial in Rural Bangladesh

Abstract

Sanitation improvements have had limited effectiveness in reducing the spread of fecal pathogens into the environment. We conducted environmental measurements within a randomized controlled trial in Bangladesh that implemented individual and combined water treatment, sanitation, handwashing (WSH) and nutrition interventions (WASH Benefits, NCT01590095). Following approximately 4 months of intervention, we enrolled households in the trial’s control, sanitation and combined WSH arms to assess whether sanitation improvements, alone and coupled with water treatment and handwashing, reduce fecal contamination in the domestic environment. We quantified fecal indicator bacteria in samples of drinking and ambient waters, child hands, food given to young children, courtyard soil and flies. In the WSH arm, Escherichia coli prevalence in stored drinking water was reduced by 62% (prevalence ratio = 0.38 (0.32, 0.44)) and E. coli concentration by 1-log (Δlog10 = −0.88 (−1.01, −0.75)). The interventions did not reduce E. coli along other sampled pathways. Ambient contamination remained high among intervention households. Potential reasons include noncommunity-level sanitation coverage, child open defecation, animal fecal sources, or naturalized E. coli in the environment. Future studies should explore potential threshold effects of different levels of community sanitation coverage on environmental contamination.

Effect of sanitation improvements on soil-transmitted helminth eggs in courtyard soil from rural Bangladesh: Evidence from a cluster-randomized controlled trial

“…Our findings of no difference in the prevalence or abundance of T. trichiura in soil between the sanitation and control arms supports the possibility that the observed reduction in T. trichiura infection in the sanitation arm could be a chance finding. Our findings are also consistent with other environmental measurements conducted among trial households showing no reduction in E. coli contamination or bacterial, viral and protozoan pathogens in soil (or other types of environmental samples) between the sanitation and control arms (48,49). A parallel study nested within the WASH Benefits Kenya trial also found no reduction in STH eggs in soil from the sanitation intervention (18).…”

The WASH Benefits and SHINE trials: interpretation of WASH intervention effects on linear growth and diarrhoea

“…Findings from our trials provide an urgent call for research to identify interventions that radically reduce faecal contamination in the household environment of low-income and middle-income countries. We term this transformative WASH. Transformative WASH might require high community coverage of improved sanitation facilities, 58 complete separation of animal faeces from people's living environments, 12,49 continuous and convenient access to uncontaminated water, 59 reductions in faecal contamination on surfaces where young children crawl and play, 46 new technologies to deliver WASH services which might differ from those implemented in high-income countries, 60 or different modalities of behaviour change. 61 Regardless of chosen technologies and interventions, transformative WASH will certainly require strengthened support for governance systems of financing, operations, monitoring, evaluation, and regulation.…”

“…In the WASH Benefits Bangladesh trial, the combined WASH and water chlorination interventions reduced the prevalence of Escherichia coli in stored drinking water and in food, but about 50% of the stored drinking water and 40% of the food still had detectable E coli, and none of the WASH interventions reduced E coli on the caregivers' or children's hands, ambient water, courtyard soil, or sentinel toys. 46,47 The combined WASH and handwashing interventions significantly reduced Giardia infection by 25%; however, 26-30% of children who received those WASH interventions were still infected with Giardia. 35 The combined WASH and water chlorination interventions reduced hookworm infection by 29-33%, but about 6% of children who received those WASH interventions were still infected with hookworm.…”

Effects of Single and Combined Water, Sanitation and Handwashing Interventions on Fecal Contamination in the Domestic Environment: A Cluster-Randomized Controlled Trial in Rural Bangladesh

“…We also sampled a random subset of households in the single water and handwashing arms to assess the impact of combined vs individual interventions. The sanitation arm was not sampled as a previous assessment showed no early environmental impact in this arm 23 and a separate longitudinal study is underway to assess the long-term effect of sanitation on environmental contamination (manuscript forthcoming). Sampling was conducted at two time points, approximately 1 and 2 years after intervention initiation, to match the timing of the trial’s health outcome measurements (see Supporting Information (SI) Text S1 and Figure S1 for details of all environmental assessments nested within WASH Benefits).…”