Results of a 12-month long enhanced surveillance of listeriosis in Italy.

Since 1993, the reporting of listeriosis has been mandatory in Italy. The surveillance system based on case notifications from physicians is managed by the Ministry of Health. The information collected includes only gender, age and case distribution by region. To gather more information, an active surveillance was conducted for 12 months (2002-2003). All hospital microbiological laboratories in Italy (n=103) were given clinical and food questionnaires and were requested to report positive cases and send strains for testing. A higher number of cases of listeriosis were reported by this active surveillance compared to the mandatory notifications. In addition, information on risk factors, clinical symptoms and outcomes of 77 reported cases were analysed. In one case it was possible to trace the source of infection. Of the 77 cases of listeriosis, 41 Listeria monocytogenes isolates were characterised by serotype and pulsotype. More than 95% of the strains belonged to serotypes 1/2a, 4b and 1/2b; molecular analysis revealed 23 different AscI pulsotypes. The information collected is very important for understanding the real situation of listeriosis in Italy. It can be used to take effective actions in improving food safety and to provide dietary advice to individuals at greater risk of infection.