Quantitative Microbial Risk Assessment For Escherichia Coli O157:H7 In Mutton In Qatar
Authors: Mohammed Hussni 
Published: November 2013

Background and Introductionâ€”Foodborne illness has been identified as one of the major hindrances to the advancement of health around the world and bacterial pathogens play a major role in this impediment. Although most of the infections are self-limited, different estimates of the cost of illnesses around the world indicate costly episodes with the numbers ranging from $1,600 to $3,000. The global risk of the foodborne pathogens has been exacerbated by globalization of trade and ease of travel around the world. Qatar is where these two factors intersect. Understanding the pathway by which these threats enter the food chain and pose risk to humans will help in developing risk mitigation strategies. In this study we assessed the potential risk of illness from the consumption of mutton contaminated with Escherichia coli O157:H7 in Qatar and identified critical intervention points that would contribute to mitigating its associated risk. Methodsâ€”We used the quantitative risk assessment (QRA) methodology using a combination of deterministic and stochastic approaches to address the stated objectives. The QRA approach helps in identifying stages in the production system from farm-to-table that are likely to play roles in mitigating or exacerbating the risk of illness associated with this pathogen (Figure 1). Data on the probability of E. coli O157:H7 in animals, animal products, retail products, and humans were obtained through repeat cross-sectional studies in these populations. Estimates of the adverse health effects were obtained using risk characterization which integrated data on hazard characterization and exposure assessment, including a dose-response model. A Monte Carlo simulation of inputs in the model was performed using the @Risk software (Palisade Software, Newfield, NY, USA) and parameters were obtained using Latin Hypercube sampling. Sensitivity analyses were performed to capture the effect of uncertainty and variability of the different parameters used in the model on the predicted risk of illness. Resultsâ€”The probability of illness from the consumption of mutton contaminated with E. coli O157:H7 for a healthy female eating at a restaurant range from 7 x 10-3 to 28 x 10-2 depending on the amount of food consumed (Figure 2). However, the risk for the same female eating at home is less (5 x 10-3 to 24 x 10-2). The estimates of illness are three times higher for immune compromised females exposed either at the restaurant or at home. We also evaluated the risk for healthy males exposed at restaurants under similar circumstances and their risk was higher than for females (13 x 10-3 to 44 x 10-2). A similar trend of reduced risk was observed for men exposed at home (9 x 10-3 to 32 x 10-2). The risk of illness due to this pathogen could be significantly reduced for either gender under different scenarios by increasing the roasting of mutton before consumption. Conclusionsâ€”This model provides a science-based justification for the awareness about the importance of the probability of adverse health effects due to E. coli O157:H7 in mutton and establishes a scientific foundation for risk managers and public health professionals.