Prevalence of Diarrhoeagenic Escherichia Coli and Associated Risk Factors in Dug Wells in Ile-Ife, Southwestern Nigeria
Abstract BackgroundDiarrhoeagenic Escherichia coli (DEC) strains are common bacterial causes of morbidity and mortality in young children. Waterborne DEC could pose a potential health risk to humans through domestic use of contaminated water. However, epidemiological studies on DEC strains in drinking water are scarce in Nigeria. This study determined the prevalence, diversity and factors associated with the presence of DEC in dug wells in Ile-Ife, southwestern Nigeria.MethodsWe assessed 143 wells for safety by coliform count using the multiple tube technique. A standardized questionnaire was used to obtain relevant information about the wells and their owners. Contaminating isolates were identified as E. coli by amplifying their 16S rRNA gene. Five DEC pathotypes comprising enterotoxigenic E. coli (ETEC), enteroaggregative E. coli (EAEC) enteroinvasive E. coli (EIEC), enteropathogenic E. coli (EPEC) and Shiga-toxin producing E. coli (STEC) were detected using two sets of multiplex PCR assays. Isolates diversity was determined by (GTG)5 Repetitive element palindromic PCR and Shannon diversity index. Multivariate logistic regression analysis was used to identify associated risk factors. Results Fifty-eight (40.6%) wells were contaminated by diarrhoeagenic E. coli. Wells with dirty platforms, damaged by erosion and sited near septic tanks significantly harboured DEC (p<0.05). There was a preponderance of STEC among the isolates with nine isolates carrying multiple diarrhoeagenic genes and 10 (17.2%) wells contaminated by multiple DEC strains. The (GTG)5-PCR fingerprinting assigned all DEC strains into six clades, with an overall Shannon diversity index of 18.87. A diverse profile was obtained among and between the isolates recovered from different sources.ConclusionsThe presence of DEC strains in drinking water highlights the risk to human health associated with the use of untreated water. There was a high degree of genetic diversity among the isolates implying multiple sources of contamination. There is a need for periodic sanitation and inspection of wells for cracks to prevent seepages and possible outbreaks of waterborne diseases.