A chicken processing model for quantitative microbiological risk assessment of Campylobacter

A "farm to fork" risk model will be constructed for the CARMA (Campylobacter Risk Management and Assessment) project. Aim of the model is not only to assess human exposure to Campylobacter as a consequence of the consumption of chicken meat, but also to compare the effects of intervention measures proposed to reduce risks. As part of this model, a chicken processing model is being developed. This model describes the transmission of Campylobacter through industrial processing of broiler chickens. The model is different from previously developed models: it is a dynamic non-linear model which, in all relevant stages of the process, explicitly incorporates cross contamination, both from chicken to chicken as by fecal leakage, and inactivation and removal of Campylobacter. This is particularly relevant when the effects of interventions should be evaluated. By lack of suitable quantitative data, a formal expert judgement study has been performed to obtain estimates of the model parameters. These estimates, with their attending uncertainty, have been derived from the results of individual interviews with 12 independent experts. The experts' assessments were weighted for their performance, calibrated by a separate set of questions. With the model, we can compare the effects on broiler chicken contamination of different sets of control measures like hygienic measures at the farm, logistic slaughter, decontamination during processing and decontamimation at the end of processing, etc. The first results of this comparison and its impact on the integrative approach applied within the CARMA project will be shown.