European monitoring programs of Salmonella
Given the importance of salmonellosis as a foodborne zoonosis the member states of EU have established similar national monitoring programs of Salmonella in pig farms. Under these programs, pigs arriving at the slaughterhouse are sampled after they are slaughtered and meat juice after freezing and thawing of diaphragmatic muscle is tested using a mix-ELISA for Salmonella. Depending on the results, the sensitivity of the method (regarding the cut-off optical density (OD) value of the ELISA test) and using a different scoring system, each country categorises the farms in one category regarding the load of Salmonella. E.g. a category zero farm is a farm that is clean of Salmonella in three consecutive tests, while a category three farm is a heavily infected farming showing high scores in all of the three consecutive tests (Alban et al., 2002a; NRLSalmonella, 2010).
Farms with high scores may be forced to take measures to reduce the level of infection with Salmonella in pig farms. Pigs coming from farms with high scores are slaughtered last at the day, while the price for them may be substantially lower, acting as an incentive for the farmers to improve the situation in their farm (Alban et al., 2002a).