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IntroductionWe previously assessed the effect of an onsite sanitation intervention in informal neighborhoods of urban Maputo, Mozambique on enteric pathogen detection in children after two years of follow-up (Maputo Sanitation [MapSan] trial, clinicaltrials.gov: NCT02362932). We found significant reductions in Shigella and Trichuris prevalence but only among children born after the intervention was delivered. In this study, we assess the health impacts of the sanitation intervention after five years among children born into study households post-intervention.Methods and analysisWe are conducting a cross-sectional household study of enteric pathogen detection in child stool and the environment in the 16 MapSan study neighborhoods at compounds (household clusters sharing sanitation and outdoor living space) that received the pour-flush toilet and septic tank intervention at least five years prior or meet the original criteria for trial control sites. We are enrolling at least 400 children (ages 29 days-60 months) in each treatment arm. Our primary outcome is the prevalence of 22 bacterial, protozoan, and soil transmitted helminth (STH) enteric pathogens in child stool using the pooled odds ratio across the outcome set to assess the intervention effect. Secondary outcomes include the individual pathogen detection prevalence and gene copy density of 27 enteric pathogens (including viruses); mean height-for-age (HAZ), weight-for-age (WAZ), and weight-for-height (WHZ) z-scores; prevalence of stunting, underweight, and wasting; and the 7-day period-prevalence of caregiver-reported diarrhea. All analyses are adjusted for pre-specified covariates and examined for effect measure modification by age. Environmental samples from study households and the public domain are assessed for pathogens and fecal indicators to explore environmental exposures and monitor disease transmission.Ethics and disseminationStudy protocols have been reviewed and approved by human subjects review boards at the Ministry of Health, Republic of Mozambique and the University of North Carolina at Chapel Hill. De-identified study data will be deposited at https://osf.io/e7pvk/.Trial registration numberISRCTN86084138STRENGTHS AND LIMITATIONS OF THIS STUDYFollow-up to the first controlled health impact trial of an urban on-site sanitation intervention after at least 5 years of intervention conditions. Previous studies have focused on WASH intervention impacts up to 2-3 years after delivery, which may be insufficient time to realize impacts.Primary study endpoint is molecular detection of multiple enteric pathogens in child stool, which unambiguously indicates previous exposure to specific sanitation-related pathogens; enteric pathogens are also assessed across multiple environmental compartments to explore environmental exposures and monitor disease transmission.Primary outcome is the overall impact of the intervention on enteric pathogen exposure using a novel pooled estimate of the treatment effect across a pre-specified set of enteric pathogens.As an observational evaluation of an existing intervention, sample size is constrained by the number of eligible children residing at study sites and selection bias arising from differential enteric pathogen-related mortality may be present, particularly among older age groups.As a cross-sectional study, there is potential for confounding bias in our estimates of the intervention impacts on child health; in particular, the presence of the intervention itself may have influenced the desirability of the intervention sites and thus the socioeconomic status of their residents, which may be associated with increased pathogen exposures.

SummaryBackgroundChildhood exposure to enteric pathogens associated with poor sanitation contributes to undernutrition, associated with adverse effects later in life. This trial assessed the independent and combined effects of nutrition and sanitation interventions on child growth outcomes and enteric pathogen infection in rural Cambodia, where the prevalence of childhood stunting remains high.MethodsWe conducted a factorial cluster-randomised controlled trial of 4,015 households with 4,124 children (1-28 months of age at endline) across three rural provinces in Cambodia. Fifty-five communes (clusters) were randomly assigned to a control arm or one of three treatments: a nutrition-only arm, a sanitation-only arm, and a combined nutrition and sanitation arm receiving both treatments. The primary outcome was length-for-age Z-score (LAZ); other outcomes included weight-for-age Z-score (WAZ), weight-for-length Z-score (WLZ), stunting, wasting, underweight, and caregiver-reported diarrhoea. We assayed stool specimens from a subset of all children (n = 1,620) for 27 enteric pathogens (14 bacteria, 6 viruses, 3 protozoa, and 4 soil-transmitted helminths) and estimated effects of interventions on enteric pathogen detection and density. Analysis was by intention-to-treat. The trial was pre-registered with ISRCTN Registry (ISRCTN77820875).FindingsSelf-reported adherence was high for the nutrition intervention but uptake was low for sanitation. Compared with a mean LAZ of -1.04 (SD 1.2) in the control arm, children in the nutrition-only arm (LAZ +0.08, 95% CI -0.01-0.18) and combined nutrition and sanitation arm (LAZ +0.10, 95% CI 0.01-0.20) experienced greater linear growth; there were no measurable differences in LAZ in the sanitation-only arm (LAZ -0.05, 95% CI -0.16-0.05). We found no effect of any intervention (delivered independently or combined) on either enteric pathogen frequency or pathogen load in stool. Compared with a mean WAZ of -1.05 (SD 1.1) in the control arm, children in the nutrition-only arm (WAZ +0.10, 95% CI 0.00-0.19) and combined intervention arm (WAZ +0.11, 95% CI 0.03-0.20) were heavier for their age; there was no difference in WAZ in the sanitation-only arm. There were no differences between arms in prevalence of stunting, wasting, underweight status, one-week period prevalence of diarrhoea, pathogen prevalence, or pathogen density in stool.InterpretationImprovements in child growth in nutrition and combined nutrition and sanitation arms are consistent with previous efficacy trials of combined nutrition and sanitation interventions. We found no evidence that the sanitation intervention alone improved child growth or reduced enteric pathogen detection, having achieved only modest changes in access and use.FundingUnited States Agency for International Development (USAID), contracts AID-OAA-M-13-00017 and AID-OAA-TO-16-00016. The contents of this publication are the sole responsibility of the authors and do not necessarily reflect the views of USAID or the United States Government.