Flaminio et al.
Epidemiology of tick-borne diseases diagnosed in patients in north-eastern Italy, 2015-2022. BMC Infect Dis. Published online March 16, 2026. doi:10.1186/s12879-026-13078-z
Italy overall has a low incidence of tick-borne encephalitis (TBE). Most reported cases originate from the northeastern Triveneto region, comprising Trentino–South Tyrol, Veneto, and Friuli Venezia Giulia.
The absence of mandatory reporting for all tick-borne diseases (TBDs) circulating in Italy, limited availability of diagnostic tests, and a lack of comprehensive epidemiological studies contribute to an incomplete understanding of their true incidence.
An observational retrospective study analyzed laboratory diagnoses of TBDs conducted between 2015 and 2022 across four hospitals in the Triveneto region (northeastern Italy), located in Padua, Vicenza, Belluno, and Bolzano. Screening included Lyme disease (LD), rickettsiosis, anaplasmosis, babesiosis, and TBE. In total, 49,345 clinical samples were collected across the participating centers.
The study primarily focused on testing for LD antibodies, which accounted for 78.4% of all analyzed sera. Overall, 14.8% of patients tested for LD were positive. Rickettsia IgG seropositivity ranged from 9.0% to 12.1% between 2015 and 2022.
Seropositive samples were also analyzed for Anaplasma phagocytophilum and Babesia microti.
A total of 16.7% of sera were tested for antibodies against TBE virus. Among these, 21% of patients were IgG-positive, while a smaller proportion (1%–4%) were IgM-positive. IgG seropositivity was lowest among children and highest among adults aged 30–49 years. In contrast, IgM positivity was highest in the youngest age group, suggesting that recent or acute infections occur more frequently in children.
Diagnostic data indicated a significant increase in TBE-related findings over the study period. Between 2017 and 2020, a total of 100 TBE cases were reported in the Triveneto region. The highest incidence between 2015 and 2019 was observed in Belluno province (4.9 per 100,000 inhabitants).
It should be noted that IgG signals detected using commercial ELISA assays may reflect cross-reactivity with other flaviviruses, such as West Nile virus, which circulates in parts of the Triveneto region. For greater diagnostic accuracy, confirmatory testing using methods such as virus neutralization assays is warranted.
Although Italy reports fewer TBE cases compared with neighboring countries such as Slovenia, Austria, and Switzerland, the health and economic burden in affected areas can be substantial. These findings underscore the need for improved diagnostic capacity, strengthened surveillance systems, and continued public education on TBD risks, particularly TBE, in northeastern Italy.