Tick-borne encephalitis in north-east Italy: a 14-year retrospective study, January 2000 to December 2013

• Published in: Euro surveillance : bulletin européen sur les maladies transmissibles Vol. 20; no. 40; p. 1
• Main Authors: Rezza, Giovanni, Farchi, Francesca, Pezzotti, Patrizio, Ruscio, Maurizio, Lo Presti, Alessandra, Ciccozzi, Massimo, Mondardini, Valeria, Paternoster, Claudio, Bassetti, Matteo, Merelli, Maria, Scotton, Pier Giorgio, Luzzati, Roberto, Simeoni, Josef, Mian, Peter, Mel, Rosanna, Carraro, Valter, Zanin, Alessandra, Ferretto, Roberto, Francavilla, Ermenegildo
• Format: Journal Article
• Language: English
• Published: Sweden Centre Europeen pour la Surveillance Epidemiologique du SIDA (European Centre for the Epidemiological Monitoring of AIDS) 08-10-2015
• Subjects: Adult; Aged; Animals; Encephalitis; Encephalitis Viruses, Tick-Borne - isolation & purification; Encephalitis, Tick-Borne - diagnosis; Encephalitis, Tick-Borne - epidemiology; Encephalitis, Tick-Borne - virology; Female; Humans; Immunization; Incidence; Italy - epidemiology; Ixodes - virology; Male; Middle Aged; Nervous system; Parasitic diseases; Polymerase Chain Reaction; Public health; Retrospective Studies; RNA, Viral - genetics; Seasons; Sex Distribution; Italy; Veneto Italy; Trentino-Alto Adige Italy; Friuli-Venezia Giulia Italy; tick-borne virus; epidemiology; tick-borne encephalitis; Italy
• ISSN: 1560-7917; 1025-496X; 1560-7917
• DOI: 10.2807/1560-7917.ES.2015.20.40.30034

Italy is considered at low incidence of tick-borne encephalitis (TBE), and the occurrence of human cases of TBE appears to be geographically restricted to the north east of the country. However, most information to date derives from case series, with no systematic data collection. To estimate incidence rates (IR) and spatial distribution of TBE cases, we conducted a retrospective study in north-eastern Italy. Data were collected through the infectious disease units and public health districts of three regions (Friuli Venezia Giulia, Trentino Alto Adige and Veneto) between 2000 and 2013. Overall, 367 cases were identified (IR: 0.38/100,000). The cases' median age was 56 years and 257 (70%) were male. Central nervous system involvement was reported in 307 cases (84%). Annual fluctuations in case numbers occurred, with peaks in 2006 and in 2013, when 44 and 42 cases were respectively observed. A strong seasonality effect was noted, with the highest number of cases in July. In terms of geographical location, three main endemic foci with high TBE IR (>10/100,000) were identified in three provinces, namely Belluno (Veneto region), Udine (Friuli Venezia Giulia) and Trento (Trentino Alto-Adige). When investigating the whole study area in terms of altitude, the IR between 400 and 600 m was greater (2.41/100,000) than at other altitudes (p<0.01). In conclusion, the incidence of TBE in Italy is relatively low, even considering only the three known affected regions. However, three endemic foci at high risk were identified. In these areas, where the risk of TBEV infection is likely high, more active offer of TBE vaccination could be considered.