Czupryna et al.
Clinical characteristics, laboratory findings, and risk factors for severe tick-borne encephalitis (TBE) in northeastern Poland: Analysis of 1654 hospitalized cases between 1993 and 2023. Int J Infect Dis. 2026;167:108549. doi:10.1016/j.ijid.2026.108549
In Poland, TBE cases have mostly been reported from the Podlaskie and Warmian-Masurian Voivodeships. In recent years, infections have also increasingly been detected in other regions, e.g., the Mazowieckie Voivodeship. In 2024, 803 cases were reported, which represented an incidence of 2.14 per 100,000 population.
A retrospective study was conducted to assess the demographic, clinical, and laboratory characteristics of TBE patients, to compare parameters among patients with different clinical manifestations, and to identify risk factors for an unfavorable outcome.
The study included 1,654 TBE patients diagnosed with neuroinfections caused by TBE virus and hospitalized at the University of Białystok (Podlaskie Voivodeship) between 1993 and 2023. All patients had developed the second phase of TBE and were antibody positive. Overall, 56.2% of the patients were urban residents, whereas 43.8% lived in rural areas. The median age of patients was 44 years.
Of the 1,654 patients, 828 (50.1%) presented with meningitis (M), 693 (41.9%) with meningoencephalitis (ME), and 133 (8.0%) with meningoencephalomyelitis (MEM). The MEM group had the highest median age (52 years). Laboratory analyses showed significant differences in CSF and blood parameters across the different clinical forms of TBE. For example, the MEM group demonstrated higher CSF protein levels, a predominance of neutrophils in CSF, and lower albumin quotients. The distribution of TBE clinical forms across three different age groups revealed that severe clinical forms were more frequent in older age groups, and the duration of hospitalization was significantly longer in patients with severe forms of TBE. The use of steroids did not result in statistically significant improvements in key clinical outcomes.
The most common sequelae were headache (9.7%), tiredness (4.17%), and vertigo (3.9%). Patients over 50 years of age were more prone to severe sequelae.
Only two of the 1,654 patients had complete and up-to-date vaccination. This finding underscores the need to increase vaccine coverage in endemic regions.