National Surveillance of Listeriosis

Epidemiological data

Epidemiology of Invasive Listeriosis in Italy - year 2020

Two hundred twenty-four clinical strains of L. monocytogenes were received at the ECDC Operational Contact Point for invasive listeriosis in humans, (OCP-ECDC), of the Istituto Superiore di Sanità (ISS) in 2020. All the strains, coming from different Italian regions, were accompanied by data for the collection of epidemiological and microbiological information. The number of strains sent is concordant with that recorded in previous years, despite the particular situation experienced by hospitals and, in general, by the entire national health system due to the SARS COV-19 pandemic.

From the analysis of the available epidemiological data, it is observed that 57.9% of the total cases of invasive listeriosis in 2020 concerned individuals over the age of 65 in particular, the age group between 71 and 90 years who it represents 45.7% of the total. The 46.4% of the cases of listeriosis involved males (104), 40.1% females (90); for 13.4% of cases (30) the sex was not reported in the epidemiological data sheets.

Distribution of L. monocytogenic strains by age and sex


In 77.2% of the cases reported in the epidemiological data sheet, the predominant clinical manifestation is septicemia (173) compared to cases of meningitis (15.8%, 35). In 4.0% of cases (9), flu-like symptoms were observed in pregnant women with isolation of the L. monocytogenes strain from placental swab, while 2 strains (0.9%) were isolated from newborns with respiratory distress. Clinical manifestation was not reported for 5 strains of L. monocytogenes (2.2%). In addition to advanced age, which is a known risk factor for listeriosis, many patients also had concomitant pathological conditions, including liver / kidney failure, heart disease and diabetes. It should also be noted that in 2020, in 1.4% of cases of listeriosis the concomitant pathology was also represented by pneumonia attributable to SARS COV-19 infections.

Cases of Listeriosis reported and number of isolates sent to the OCP-ECDC from 2010 to 2020

From 2010 to 2013, the number of L. monocytogenes isolates was lower than the number of notifications due to lack of availability of the isolate.

From 2014 to 2019 the number of L. monocytogenes isolates is significantly increasing, in particular for the years 2014-2015 it is higher than the number of notifications.

If on one hand this data highlights a sub-notification, on the other hand there is a better diagnostic skill of the laboratories.

For 2020, no notification data for listeriosis cases are available.

Trend in cases of listeriosis from 2010 to 2020 and corresponding notifications