Serotype distribution of Salmonella isolates from food animals after slaughter differs from that of isolates found in humans

If raw meat and poultry are the primary point of entry for Salmonella speci es into human populations, a correlation might be expected between the sero type distribution of Salmonella species isolated from animals at the time o f slaughter and that of isolates found in humans. For 1990-1996, sufficient national data were available to permit such a comparison. A mathematical m odel was developed to predict serotype distributions of Salmonella isolates among humans on the basis of animal data. There was a significant mismatch between the serotype distributions among humans predicted by the model and those actually observed. This mismatch raises questions about the validity of the "standard" assumptions about Salmonella transmission on which the m odel was based-namely, that raw animal products are the primary source for human salmonellosis, that the risk of transmission to humans is equal for a ll food product categories, and that all Salmonella serotypes have an equal ability to cause human illness.