Modelling the epidemiology of Salmonella in the pork supply chain

The interest in reducing the incidence of food-borne diseases, such as salmonellosis caused by pork is increasing. All stages in the pork supply chain can take preventive and reductive measures to decrease the Salmonella prevalence. But it is necessary to have insight in the effect of these measures on the final prevalence of contaminated carcasses. In this way imposing expensive but ineffective measures can be avoided. In order to be able to obtain such evaluations, a stochastic state-transition model is designed. Five stages are included (from piglet to carcass) and two risk-profiles are formulated for each stage: high-risk and low-risk. Scenario studies with the model indicate that all stages may contribute to an increased food safety. The impact of the multiplying stage is limited, because the animals may recover during the finishing stage. Recovery after the finishing stage is not possible, although the transport and lairage can prevent further transmission. At the slaughterhouse the number of contaminated carcasses is highly determined by the prevalence of the supplied animals and the risk profile. Measures in the finishing stage are effective in the reduction of Salmonella in pork, but may be cancelled out if the following stages do not take preventive and reductive measures.