Child hand contamination is associated with subsequent pediatric diarrhea in rural Democratic Republic of the Congo (REDUCE Program)

Leveraging infectious disease models to interpret randomized controlled trials: Controlling enteric pathogen transmission through water, sanitation, and hygiene interventions

Randomized controlled trials (RCTs) evaluate hypotheses in specific contexts and are often considered the gold standard of evidence for infectious disease interventions, but their results cannot immediately generalize to other contexts (e.g., different populations, interventions, or disease burdens). Mechanistic models are one approach to generalizing findings between contexts, but infectious disease transmission models (IDTMs) are not immediately suited for analyzing RCTs, since they often rely on time-series surveillance data. We developed an IDTM framework to explain relative risk outcomes of an infectious disease RCT and applied it to a water, sanitation, and hygiene (WASH) RCT. This model can generalize the RCT results to other contexts and conditions. We developed this compartmental IDTM framework to account for key WASH RCT factors: i) transmission across multiple environmental pathways, ii) multiple interventions applied individually and in combination, iii) adherence to interventions or preexisting conditions, and iv) the impact of individuals not enrolled in the study. We employed a hybrid sampling and estimation framework to obtain posterior estimates of mechanistic parameter sets consistent with empirical outcomes. We illustrated our model using WASH Benefits Bangladesh RCT data (n = 17,187). Our model reproduced reported diarrheal prevalence in this RCT. The baseline estimate of the basic reproduction number R 0 for the control arm (1.10, 95% CrI: 1.07, 1.16) corresponded to an endemic prevalence of 9.5% (95% CrI: 7.4, 13.7%) in the absence of interventions or preexisting WASH conditions. No single pathway was likely able to sustain transmission: pathway-specific R 0 s for water, fomites, and all other pathways were 0.42 (95% CrI: 0.03, 0.97), 0.20 (95% CrI: 0.02, 0.59), and 0.48 (95% CrI: 0.02, 0.94), respectively. An IDTM approach to evaluating RCTs can complement RCT analysis by providing a rigorous framework for generating data-driven hypotheses that explain trial findings, particularly unexpected null results, opening up existing data to deeper epidemiological understanding.

Fecal Sampling of Soil, Food, Hand, and Surface Samples from Households in Urban Slums of Dhaka, Bangladesh: An Evidence-Based Development of Baby Water, Sanitation, and Hygiene Interventions

The aim of this study was to identify the exposure pathways of fecal pathogens for a pediatric population living in the urban slums of Bangladesh. A total of 252 soil, food, surface, and hand rinse samples were collected from the pilot households with children less than 5 years of age. All samples were analyzed using the IDEXX Quanti-Tray System (Colilert-18) to enumerate fecal indicator bacteria Escherichia coli. Escherichia coli was detected in all soil samples collected from children play spaces (N = 46), 35% of objects and surfaces children frequently put in their mouths, and 31% of child food samples. Thirty-three percent of hand samples from the child and 46% of hand samples from the caregiver had detectable E. coli. These findings showed high fecal contamination of soil, food, and on hands and surfaces in households with young children and demonstrate the need for interventions reducing these exposure pathways for susceptible pediatric populations.

Hygiene in early childhood development centres in low-income areas of Blantyre, Malawi

Diarrhoeal disease remains a leading cause of death in children in sub-Saharan Africa, attributed to environmental health factors such as inadequate water, sanitation and hygiene (WASH) and food hygiene. This formative study in low-income areas of Blantyre focussed on the practices in Early Childhood Development Centre (ECDCs) environments where children spend a significant amount of time. A mixed-methods approach was applied to identify key hygiene behaviours in ECDCs through; checklist and structured observations (n = 849 children; n = 33 caregivers), focus group discussions (n = 25) and microbiological sampling (n = 261) of drinking water, food handler's hands, and eating utensils. ECDCs had inadequate WASH infrastructure; coupled with poor hygiene practices and unhygienic environments increased the risk of faecal-oral disease transmission. Presence of E. coli in drinking water confirmed observed poor water handling habits by staff and children. Addressing undesired hygiene practices in ECDCs has the potential to improve the health outcomes of children in low-income settings.

Identifying psychosocial determinants of water, sanitation, and hygiene (WASH) behaviors for the development of evidence-based Baby WASH interventions (REDUCE program)

Diarrheal disease remains a leading cause of child mortality, globally. In the Democratic Republic of the Congo (DRC), each year there are an estimated 45 million episodes of diarrhea in children under five years of age. The Reducing Enteropathy, Diarrhea, Undernutrition, and Contamination in the Environment (REDUCE) program seeks to develop theory-driven, evidence-based approaches to reduce diarrheal diseases among young children. The REDUCE prospective cohort study in Walungu Territory in Eastern DRC took guidance from the risks, attitudes, norms, abilities, and self-regulation model, the integrated behavioral model for water, sanitation, and hygiene (WASH), and other behavior change theories to identify psychosocial factors associated with WASH behaviors. Psychosocial factors were measured among 417 caregivers at baseline and caregiver responses to child mouthing of dirty fomites and handwashing with soap was assessed by 5-hour structured observation at the 6-month follow-up. Caregivers who agreed that their child could become sick if they put dirt in their mouth (perceived susceptibility) and caregivers that agreed they could prevent their child from playing with dirty things outside (self-efficacy) were significantly more likely to stop their child from mouthing a dirty fomite. Higher perceived susceptibility, self-efficacy, and disgust, and lower dirty reactivity, were associated with higher handwashing with soap behaviors. This study took a theory-driven and evidence-based approach to identify psychosocial factors to target for intervention development. The findings from this study informed the development of the REDUCE Baby WASH Modules that have been delivered to over 1 million people in eastern DRC.