SALMONELLA-ENTERITIDIS INFECTIONS IN FRANCE AND THE UNITED-STATES - CHARACTERIZATION BY A DETERMINISTIC MODEL

Objectives. Epidemiological surveillance can be used to identify problems, suggest hypotheses, and assess the effectiveness of preventive actions. These objectives are pursued in the analysis of the dynamic evolution of Salmonella enteritidis infections. In this analysis, development of the epidermic in France and the United States is compared. Methods. This analysis is based on the formulation of a simple deterministic compartmental model. in which human contact with contaminated food is expressed in terms of a baseline transmission rate. Results. In France, the baseline transmission rate, stable up until 1986, is multiplied by 2.3 in 1987 and by 4.1 in 1988. There is no evidence of a slowdown of the linear rate of increase. In the Middle Atlantic region of the United States, the linear increase of the epidemic is similar to that observed in France. From 1990 a potential effect of the preventive measures is observed. Conclusions. The pattern of increase of the baseline transmission rate is similar in France and in the Middle Atlantic region of the United States. However. preventive measures, used in both areas, appeared more effective in the United States.