Risk Factors Associated with Shiga-toxin Escherichia coli Contamination of Raw Milk in Pastoralist Farms in Narok County, Kenya.

BACKGROUND: Narok County has recorded the highest global isolation of the foodborne Shiga toxin-producing Escherichia coli (STEC). Nevertheless, information regarding transmission risk in the food systems is limited. OBJECTIVE: This study aimed to investigate risk factors associated with isolation of STEC from bulked farm milk in Narok County. MATERIALS AND METHODS: STEC strains were isolated and identified using standard bacteriological and molecular methods. Management practices data were collected through face-to-face interviews. Logistic regression analyses determined the relevant predictors and model performance. RESULTS: E. coli was isolated from 15.1% (confidence interval [CI]: 9.2-21.0, n = 139) of the raw milk samples; the majority (85.7%, CI: 70.8-100.0, n = 21) of the isolates were confirmed to be STEC through multiplex polymerase chain reaction and sequencing targeting gadA, stx 1, stx 2, eaeA, and hlyA genes. Informal education (odds ratio [OR] = 30.7; 95% CI: 6.6-142.5; P < 0.001) and housing livestock (OR = 19.2; 95% CI: 5.2-71.5; P < 0.001) emerged as significant predictors of STEC isolation. Informal education and indoor housing of dairy animals were associated with increased likelihood of isolation of STEC from raw milk (adjusted OR [AOR] = 13.9, P < 0.001) and (AOR = 9.0, P < 0.001), respectively. CONCLUSIONS: Our findings provide evidence of poor milk handling practices on farms. The prevalence of STEC in milk may pose a risk to public health and food safety. Therefore, proper hygienic practices in dairy farms are recommended.