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.

Figure 1

Flowchart of participant enrollment and environmental sampling scheme. C refers to the control arm, S to the individual sanitation arm and WSH to the combined water, sanitation and handwashing arm.

Figure 2

Prevalence of caregivers and children with visible dirt on hands. C refers to the control arm, S to the individual sanitation arm and WSH to the combined water, sanitation and handwashing arm.

Figure 3

Prevalence and concentration of E. coli (in source and stored drinking water, child hand rinses, food given to young children, pond water, courtyard soil, flies) and prevalence and number of flies captured near kitchen after approximately 4 months of intervention. E. coli concentrations are reported in the log of the most probable number (MPN) per 100 mL for tubewell, stored water and pond samples, per two hands for child hand rinses, per dry gram for food and soil samples and per fly for fly samples. C refers to the control arm, S to the individual sanitation arm and WSH to the combined water, sanitation, and handwashing arm.