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

Abstract

Water, sanitation, and hygiene interventions have varying effectiveness in reducing fecal contamination in the domestic environment; delivering them in combination could yield synergies. We conducted environmental assessments within a randomized controlled trial in Bangladesh that implemented single and combined water treatment, sanitation, handwashing (WSH) and nutrition interventions (WASH Benefits, NCT01590095). After one and two years of intervention, we quantified fecal indicator bacteria in samples of drinking water (from source or storage), child hands, children's food and sentinel objects. In households receiving single water treatment interventions, Escherichia coli prevalence in stored drinking water was reduced by 50% and concentration by 1-log. E. coli prevalence in food was reduced by 30% and concentration by 0.5-log in households receiving single water treatment and handwashing interventions. Combined WSH did not reduce fecal contamination more effectively than its components. Interventions did not reduce E. coli in groundwater, on child hands and on objects. These findings suggest that WSH improvements reduced contamination along the direct transmission pathways of stored water and food but not along indirect upstream pathways. Our findings support implementing water treatment and handwashing to reduce fecal exposure through water and food but provide no evidence that combining interventions further reduces exposure.

Figure 1

Flowchart of participant enrollment and environmental sampling scheme. C represents pooled data from (i) the control arm and (ii) the nutrition arm. WSH represents pooled data from (i) the combined water, sanitation and handwashing arm and (ii) the nutrition plus combined water, sanitation and handwashing arm. W refers to the individual water treatment arm, and H to the individual handwashing arm.

Figure 2

Prevalence of caregivers and children with visible dirt on hands at year one. C represents pooled data from (i) the control arm and (ii) the nutrition arm. WSH represents pooled data from (i) the combined water, sanitation and handwashing arm and (ii) the nutrition plus combined water, sanitation and handwashing arm. H refers to the individual handwashing arm.

Figure 3

Prevalence of caregivers and children with visible dirt on hands at year two. C presents pooled data from (i) the control arm and (ii) the nutrition arm. WSH represents pooled data from (i) the combined water, sanitation and handwashing arm and (ii) the nutrition plus combined water, sanitation and handwashing arm. H refers to the individual handwashing arm.

Figure 4

Prevalence and concentration of E. coli (in source and stored drinking water, child hand rinses, sentinel toy rinses) and prevalence and number of flies captured near kitchen and latrine at year one. E. coli concentrations are reported in log colony forming units (CFU) per 100 mL for drinking water samples (tubewell and stored water), per two hands for child hand rinses and per toy for sentinel toy rinse samples. C represents pooled data from (i) the control arm and (ii) the nutrition arm. WSH represents pooled data from (i) the combined water, sanitation and handwashing arm and (ii) the nutrition plus combined water, sanitation and handwashing arm. W refers to the individual water treatment arm, and H to the individual handwashing arm.

Figure 5

Prevalence and concentration of E. coli (in source and stored drinking water, child hand rinses, sentinel toy rinses, and food given to young children) and prevalence and number of flies captured near kitchen and latrine at year two. E. coli concentrations are reported in log colony forming units (CFU) per 100 mL for drinking water samples (tubewell and stored water), per two hands for child hand rinses, per toy for sentinel toy rinse samples and per dry gram for food samples. C represents pooled data from (i) the control arm and (ii) the nutrition arm. WSH represents pooled data from (i) the combined water, sanitation and handwashing arm, and (ii) the nutrition plus combined water, sanitation and handwashing arm. W refers to the individual water treatment arm, and H to the individual handwashing arm.