A review of the Salmonellosis surveillance systems in Italy: Evolution during the course of time within the international framework

This paper focuses on the history of the two systems that have been adopted in Italy for the surveillance of Salmonellosis and describes their respective characteristics. Both systems have been subsequently modified: (1) The National Laboratory-based Surveillance System (NLSS) which was created in 1967 for Enteropathogenic Bacteria and subsequently, in 1992, became part of the European computerised Laboratory-based Surveillance System of Salmonellae isolates, the SALM-NET (Salmonella network); (2) The National Infectious Disease Reporting System (NIDRS) which was set up in the 1930s, revised in 1990 and has been used, since 1994, along with the Infectious Disease Informative System (IDIS). The results obtained with the different surveillance systems are presented: (1) The number of isolates from the laboratory surveillance from 1973 to 1997 are described. Total Salmonellae isolates have a slope with an increasing trend from 4372 isolates in 1973 to 15,041 isolates in 1988 drastically dropping to 5479 isolates in 1990 and increasing again to 13,596 isolates in 1993. Attention is given particularly to the epidemiology of S. enteritidis in Italy which increased progressively since 1982 (225 isolates) to 5435 isolates in 1994. S. typhimurium showed a slightly increasing trend in the period 1973–1988 (from 1694 to 3383 isolates) then decreased for reaching again previous levels. S. typhi showed a marked reduction from 573 isolates in 1973 to 33 isolates in 1996. On the contrary, other less frequent serotypes increased. (2) The number of cases of Salmonellosis reported during 1971–1997 are also presented. Other Infections by Salmonellae increased from 12,516 cases in 1976 (renamed Non Typhoidal Salmonellosis in 1990) to more than 20,000 cases in 1992. The number of cases of Typhoid Fever and Infections by S. paratyphi are also described. Particular attention has to be paid to the parallel trends of Salmonellosis using both surveillance systems: number of isolates and number of cases, particularly comparing Other Infections by Salmonellae and total Salmonellae isolates: after the 1992–1993 peak, an initial decrease was observed.