Animal Feces Contribute to Domestic Fecal Contamination: Evidence from E. coli Measured in Water, Hands, Food, Flies, and Soil in Bangladesh.

Ayse Ercumen,Amy J Pickering,Leanne Unicomb,Craig Kullmann,Mahfuja Alam,Rokeya Ahmed,Sarker Masud Parvez,Debashis Sen,Laura H Kwong,Claire Chase,John M Colford,Sharmin Islam,Stephen P Luby,Benjamin F Arnold

doi:10.1021/acs.est.7b01710

Abstract

Fecal-oral pathogens are transmitted through complex, environmentally mediated pathways. Sanitation interventions that isolate human feces from the environment may reduce transmission but have shown limited impact on environmental contamination. We conducted a study in rural Bangladesh to (1) quantify domestic fecal contamination in settings with high on-site sanitation coverage; (2) determine how domestic animals affect fecal contamination; and (3) assess how each environmental pathway affects others. We collected water, hand rinse, food, soil, and fly samples from 608 households. We analyzed samples with IDEXX Quantitray for the most probable number (MPN) of E. coli. We detected E. coli in source water (25%), stored water (77%), child hands (43%), food (58%), flies (50%), ponds (97%), and soil (95%). Soil had >120 000 mean MPN E. coli per gram. In compounds with vs without animals, E. coli was higher by 0.54 log10 in soil, 0.40 log10 in stored water and 0.61 log10 in food (p < 0.05). E. coli in stored water and food increased with increasing E. coli in soil, ponds, source water and hands. We provide empirical evidence of fecal transmission in the domestic environment despite on-site sanitation. Animal feces contribute to fecal contamination, and fecal indicator bacteria do not strictly indicate human fecal contamination when animals are present.

Highlights

Fecal-oral pathogens are transmitted from feces to new hosts through complex, environmentally mediated pathways
fecal indicator bacteria (FIB) and pathogens have been detected in soil[12] and geophagia has been associated with diarrhea, markers of environmental enteric dysfunction, and stunting in young children.[13,14]
Field workers administered a structured questionnaire on animal husbandry. They observed water, sanitation, and hygiene indicators, including the cover status of the storage containers from which the drinking water and food samples were collected, presence of a handwashing station with soap and water within 10 m of the latrine, and presence and number of latrines in the compound and within 10 m of tubewells and ponds. They differentiated improved latrines based on Joint Monitoring Programme (JMP) categories[26] and observed whether the latrine drained into a septic tank, pit, or the environment

Summary

Introduction

Fecal-oral pathogens are transmitted from feces to new hosts through complex, environmentally mediated pathways. The complexity arises from a multitude of transmission pathways, a broad diversity of pathogens, the influence of environmental conditions and interactions between the environment and human behavior. In the absence of effective sanitation and sewerage facilities that isolate human feces from the environment, human fecal organisms can spread into fields and ambient waters. These are subsequently transported by fomites and vectors (e.g., hands, flies) into drinking water and food as well as ingested through mouth contact with contaminated hands and objects or geophagia (deliberate ingestion of soil) by young children.[1,2]. FIB and pathogens have been detected in soil[12] and geophagia has been associated with diarrhea, markers of environmental enteric dysfunction, and stunting in young children.[13,14] it has not been documented how soil contamination affects

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