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

Abstract

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.