Annual data from the Finnish National Salmonella Control Programme were used to build up a probabilistic model of salmonella in the primary production chain of cattle beef. The primary production chain of beef was described by a hierarchical stochastic model using Bayesian methods and MCMC sampling. The model combines herd level and animal level observations along the primary production chain up to the lymph node samples taken at the slaughter stage. Posterior distributions for the current true prevalence were computed accounting for the overall sensitivity both at herd level and individual level of testing. The effects of intervention mechanisms will be evaluated by posterior predictive distributions. The model is the first part of three modules describing the whole production chain up to the consumers.

National Veterinary and Food Research Institute (EELA)Department of Risk Assessment