Epidemiological and economic simulation of Salmonella control in the pork supply chain

Pork can be regarded as an important source for food borne salmonellosis. Salmonella bacteria can be introduced and spread in every stage of the pork supply chain and cause a risk for food safety. The objective of this research is to gain insight into the epidemiological and economic effects of different strategies in the finishing, transport, lairage and slaughtering stages to improve the food safety of pork with respect to Salmonella. To collect information on possible control measures and on details of the course of infection and contamination, a survey among 75 experts in the Netherlands and Denmark was carried out. Knowledge (both from experts and from literature) about the interaction and relations between the epidemiological and economic aspects was limited. Therefore, two separate models were designed, one for the epidemiological aspects and one for the economic aspects of Salmonella control in the pork supply chain. The epidemiological model to simulate the introduction and spread of Salmonella in the pork supply chain is a detailed stochastic state transition model. The economic model is a deterministic simulation model. For each control measure in the finishing to slaughtering stages, the costs and revenues have been calculated using the technique of partial budgeting. Since it is not feasible in practice to implement all possible control measures, for each stage a package of measures has been defined by selecting feasible measures. The net costs for these packages per stage were calculated per pig. In the finishing stage, the net costs for the control package are € 2.99, for the transportation stage € 0.65, for the lairage € 0.40 and for the slaughtering stage € 1.47. Combining the results of the epidemiological and the economic models allowed comparison of the cost-effectiveness of different control strategies for Salmonella in the pork supply chain. The research has revealed the importance of a chain approach instead of considering each stage individually. The effectiveness of Salmonella reduction depends on the efforts of all participants in a stage. A small number of poorly performing participants can disproportionately reduce the effectiveness of the efforts of the other participants. A payment system based on the Salmonella prevalence of the supplied animals or carcasses is a promising strategy to improve food safety. Strategic management principles have been applied to define aspects that are important for the design and implementation of a Salmonella control program in the entire pork supply chain. Two possible control programmes are described: a Food Safety Program and a Competitive Program.