Temporal patterns in the occurrence of Salmonella in raw meat and poultry products and their relationship to human illnesses in the United States

The prevalence and level of microbial pathogens on various commodities often exhibit seasonal patterns. As a consequence, the incidence of foodborne illness tends to follow these trends. Of the various product classes, the occurrence of microbial contamination can be high on raw meat and poultry products, with Salmonella potentially occurring in all meat and poultry product classes. Since 1999, the Food Safety and Inspection Service in the United States has collected samples of meat and poultry products and analyzed them for the presence of Salmonella. This study uses a common modeling approach to estimate the seasonal change in the proportion of test-positive samples for seven classes of raw meat and poultry products. The results generally support the hypothesis of a seasonal increase of Salmonella during the summer months. The proportions of test-positive samples decrease rapidly in the late fall for all product classes except chicken and ground turkey, which remain somewhat elevated through late winter. A comparison of the pathogensʹ seasonal pattern in meat and poultry with human cases reveals that the seasonal increase in human cases precedes the seasonal increase in meat and poultry by between one and three months. These results suggest that while contaminated meat and poultry products may be responsible for a substantial number of human cases, they are not necessarily the primary driver of the seasonal pattern in human salmonellosis.