The objective of the Swedish salmonella control is to ensure that food of animal origin is free from salmonella. The strategy is to prevent infection/contamination in feed and animals. Any finding of salmonella is notifiable and action is always taken to eliminate the infection. Repeated surveys have been performed in order to control the efficacy of the salmonella control (Robertsson, 1976; Wierup et al., 1992; Wahlstrom et al., 1993; Hopp et al., 1996). Since 1995 continuos monitoring programmes aimed at documenting the prevalence of Salmonella and detecting foci of infection are in force (Anonymous, 1995).