Alfano et al.
Tick-borne encephalitis foci in northeast Italy revealed by combined virus detection in ticks, seroprevalence on goats and human cases
Emerg. Microbes Infect. 2020, 9:1, 474-484
In Italy, TBE has been reported since 1967, and the virus was first isolated in 1975. Most cases are reported from the northeastern part of the country, from Trentino-Alto Adige, Veneto and Friuli Venezia Giulia. In this area, the number of cases has increased over time, and the annual incidence has increased from 0.06 in 1992 to 0.88 cases per 100,000 inhabitants in 2006. In the Province of Trento, which is part of the Trentino-Alto Adige region, the risk to acquire TBE has been analyzed by a wide serological screening in goats combined with determining the prevalence of TBE virus in ticks and identifying human cases.
During 2017, 706 goat serum samples from 69 farms were analyzed by TBE ELISA and 1.3% were found positive or borderline (15.1%). 116 of these samples were then analyzed by neutralization test. Finally, 1.56% revealed TBE positive. A total of 2.410 questing Ixodes ricinus ticks were collected and an overall prevalence of 0.17% of infected ticks was measured. Sequencing of the glycoprotein E gene revealed that four isolated strains belong to the European subtype and were genetically closely related to strains from neighboring countries. Between 1992 and 2019, 174 TBE cases were diagnosed in Trentino and from 2012 onwards, a sharp rise in the number of cases has been observed. These combined data highlight the importance of an integrated approach for TBE risk evaluation of a region and show an updated picture of TBE hazard in the Province of Trento. Although TBE vaccine has been offered free of charge to the whole resident population since 2018, the number of TBE cases remained high in 2019.