Ingestion of Fecal Bacteria along Multiple Pathways by Young Children in Rural Bangladesh Participating in a Cluster-Randomized Trial of Water, Sanitation, and Hygiene Interventions (WASH Benefits)

Laura H Kwong,Sarker M Parvez,Mahbubur Rahman,Stephen P Luby,Ayse Ercumen,Leanne Unicomb,Mahfuza Islam,Amy J Pickering,Jennifer Davis,Joanne E Arsenault

doi:10.1021/acs.est.0c02606

Abstract

Quantifying the contribution of individual exposure pathways to a child’s total ingestion of fecal matter could help prioritize interventions to reduce environmental enteropathy and diarrhea. This study used data on fecal contamination of drinking water, food, soil, hands, and objects and second-by-second data on children’s contacts with these environmental reservoirs in rural Bangladesh to assess the relative contribution of different pathways to children’s ingestion of fecal indicator bacteria and if ingestion decreased with the water, sanitation, and hygiene interventions implemented in the WASH Benefits Trial. Our model estimated that rural Bangladeshi children <36 months old consume 3.6–4.9 log10 most probable number E. coli/day. Among children <6 months, placing objects in the mouth accounted for 60% of E. coli ingested. For children 6–35 months old, mouthing their own hands, direct soil ingestion, and ingestion of contaminated food were the primary pathways of E. coli ingestion. The amount of E. coli ingested by children and the predominant pathways of E. coli ingestion were unchanged by the water, sanitation, and hygiene interventions. These results highlight contaminated soil, children’s hands, food, and objects as primary pathways of E. coli ingestion and emphasize the value of intervening along these pathways.

Highlights

Exposure to human and animal fecal contamination causes enteric infections and fecal-oral diseases including diarrhea
There is evidence that inadequate child feces management impairs child growth;[11] exposure to animal feces and soil is associated with increased risk of diarrhea, markers of environmental enteropathy, and growth faltering;[12−15] and objects carry fecal contamination that may be ingested by children when objects are mouthed.[16,17]
A substantial fraction of the E. coli ingested by children is from pathways that are not directly addressed by household-level water, sanitation, and hygiene interventions: directly ingesting soil that is contaminated by animal feces and mouthing hands and objects contaminated by this soil

Summary

Introduction

Exposure to human and animal fecal contamination causes enteric infections and fecal-oral diseases including diarrhea. Repeated exposure to high levels of fecal contamination may contribute to environmental enteropathy, a subclinical condition of the small intestine associated with blunted intestinal villi and crypt hyperplasia.[1] Environmental enteropathy and enteric infections contribute to malnutrition, which caused 1.4 million deaths in 2015.2 Malnutrition is associated with delayed and reduced schooling, and long-term cognitive impairment.[3,4]. There is evidence that inadequate child feces management impairs child growth;[11] exposure to animal feces and soil is associated with increased risk of diarrhea, markers of environmental enteropathy, and growth faltering;[12−15] and objects carry fecal contamination that may be ingested by children when objects are mouthed.[16,17]

Methods

Results

Conclusion