Environmental and behavioral exposure pathways associated with diarrhea and enteric pathogen detection in twenty-six week old urban Kenyan infants: a cross-sectional study

The prevalence of enteric pathogen detection in children in low-income countries climbs rapidly between birth and 6 months of age. Few studies have tested whether improved household environmental and behavioral hygiene conditions protects infants from exposure to enteric pathogens spread via unhygienic human and animal sanitation conditions, especially during this early window of infancy. This cross-sectional study utilized enrollment survey data among households with 6 month old infants in Kisumu, Kenya participating in the Safe Start cluster-randomized controlled trial to estimate associations between household water access and treatment, animal vectors, sanitation access, hand washing practices, supplemental feeding, and flooring, with the outcomes of caregiver-reported 7-day diarrhea prevalence and sum count of different enteric viruses, bacteria, and parasites pathogens in infant stool. Then, we tested whether household environmental hygiene and behavioral practices moderated associations between infant exposure outcomes and latrine access and domestic animal co-habitation. We found that reported handwashing after handling animals and before eating were strongly associated with lower risk of caregiver-reported diarrhea, while owning and co-habitating with animals (versus no animals), living in a household with vinyl covered dirt floors (versus finished floors), and feeding infants cow milk (versus no milk) were strongly associated with pathogen detection in infants. Caregiver handwashing after child or self-defecation moderated the relationship between shared sanitation (vs private) sanitation access and infant exposure to pathogens such that handwashing had the greatest benefit for preventing pathogen exposure of infants in households with private latrines. In the absence of handwashing, access to private sanitation posed no benefits over shared latrines for protecting infants from exposure. Our evidence highlights eliminating animal co-habitation, improving flooring, improving post-defecation and food-related handwashing, and improving safety of cow milk sources and/or safe household storage of milk as interventions to prevent enteric pathogen exposure of infants less than 6 months age. Key QuestionsO_ST_ABSWhat is already known?C_ST_ABSThe population prevalence of enteric infections and diarrhea climbs rapidly in the first year of life. Risk factors for pediatric infections include unhygienic human and animal sanitary conditions that introduce feces into the environment, as well as intermediate environmental and behavioral exposure pathways. Research examining the mitigating role of improved environmental and behavioral conditions in preventing infant exposure to human and animal sanitary conditions is limited. What are the new findings?Contact with domestic animals and feeding infants cow milk are leading risk factors for exposure to enteric pathogens by 6 months age in Kisumu, while handwashing after animal handling and before eating are protective factors against self-reported diarrhea. The benefits of access to a private improved latrine (versus shared) for protecting infants from pathogen exposure were conditional upon caregivers washing hands after defecation or child-defecation. What do the new findings imply?Interventions that keep animals out of infant living spaces and that improve food-related and post-defecation handwashing may be the most effective strategies for controlling the population prevalence of enteric infections in infants between birth and 6 months age in Kisumu and similar settings.