Epidemiology and risk factors for diarrhoeagenic Escherichia coli carriage among children in northern Ibadan, Nigeria

Diarrhea is a leading cause of childhood morbidity in Africa. Outside of multi-country sentinels, of which there are none in Nigeria, few studies focus on bacterial etiology. We performed a case-control study among children under five years of age. Stool specimens were collected from 120 children with, and 357 without, diarrhea attending primary health clinics on the northern outskirts of Ibadan between November 2015 and August 2019. Up to ten E. coli isolates were obtained per specimen and at least three were whole genome-sequenced using Illumina technology. Genomes were assembled using SPAdes, quality evaluated using QUAST, and Virulencefinder was used to identify virulence genes. The microbiological quality of water from 14 wells within the study area was assessed using total and coliform counts. Diarrhoeagenic Escherichia coli (DEC) were isolated from 79 (65.8%) of cases and 217 (60.8%) control children. All DEC pathotypes except Shiga toxin-producing E. coli, a number of hybrid DEC pathotypes, Salmonella and Yersina spp. were detected but no pathogen showed association with disease (p>0.05). Enterotoxigenic E. coli were more commonly recovered from younger controls but exclusively detected in cases aged over nine months. Temporally-linked, highly similar enteroaggregative E. coli were isolated from children in different households in eight instances. No well water sample drawn in the study qualified as potable. Children in northern Ibadan are commonly colonized with DEC. Access to water and sanitation, and vaccines targeting the most abundant pathogens may be critical for protecting children from the less overt consequences of enteric pathogen carriage.