Purpose: To trace the sources of contamination for individual Salmonella-positive carcasses at the end of the slaughter line.
Methods: The model is a Bayesian Belief Network, in which Salmonella concentration information at different locations in the slaughterhouse are used in combination with prior knowledge about the dynamics of Salmonella through the slaughter line. Data, collected in a Dutch slaughterhouse, were used to specify prior beliefs about the model inputs and to iteratively refine the distributions of the parameters in the model so that it optimally describes that specific slaughterhouse.
Results: The model results indicate that house flora on or in the carcass splitter was the causative source of contamination for many carcasses, especially for those that carried contamination on the cutting side. Furthermore, the model indicates that the parameter values of the model may be subject to temporal variation and can be used as a tool to provide estimates of such trends.
Significance: The model shows the concept of biotracing, gives insight in the dynamics of Salmonella in the slaughter line and indicates the sites in the line where collecting data is most effective for biotracing. This biotracing model is implemented as an interactive computer application, which can be seen as a step in the process towards an operational biotracing system, by which a stakeholder can initiate immediate responses to Salmonella contamination and other hazards imposed in the pork slaughterhouse.