ABSTRACT
I. BACKGROUND Salmonella continues to be a major cause of food poisoning throughout the world. Salmonellosis sickens as many as 3.84 million Americans and costs billions of dollars in lost productivity and medical costs per year (1,2). The number of reported cases of salmonella infection in both the United States and many European countries has also increased in recent years. Switzerland averaged a 51% increase per year since 1984 (3), and in Spain salmonellae are the principal agent of gastroenteritis (4). In many cases this increase has been due to a particular serotype, Salmonella enterica serotype Enteritidis, found primarily in poultry and poultry products. Italy reported a more than 6-fold increase in the number of Enteritidis outbreaks between 1990 and 1991 (3); the increase in Spain was 10-fold between 1983 and 1987 (3). In England, the number of cases increased 6-fold between 1982 and 1988 (3); France experienced a 7-fold increase between 1986 and 1990 (5). It appears, however, that the Enteritidis epidemic peaked in humans in 1992 in many European countries. The subsequent slight decline may set the stage for the reemergence of Typhimurium as the dominant serotype in human salmonellosis.
