Skudal et al.
Clinical characteristics and factors affecting disease severity in hospitalized tick-borne encephalitis patients in Norway from 2018 to 2022
Eur. J. Clin. Microbiol. Infect. Dis. 2024. doi:10.1007/s10096-024-04855-2
TBE has been a mandatory notifiable disease in Norway since 1975, but it was not diagnosed in the country until 1997. Since then, the incidence remained low. With an average of fewer than seven cases reported annually until 2017. However, there has been a significant increase in reported cases since then, with 113 cases in 2023. Nearly all TBE virus infections occur in the coastal regions of southern Norway.
An observational study to assess disease severity was conducted in the endemic area of Norway from 2018 to 2022, including a total of 153 TBE patients aged 18-87 years. More than half of the patients experienced moderate disease. Additionally, 54% of the patients reported one or more comorbidities, such as hypertension (20%), allergies (14%), and chronic heart disease (11%). Those with severe disease had more comorbidities compared to patients who were mildly or moderately affected.
Patients with any comorbidities had an eightfold higher risk of developing severe disease compared to those without comorbidities. There was one fatal case involving a 78-year-old male patient. None of the patients were fully vaccinated. Forty-six percent of the patients had a monophasic disease, and no correlation was found between the disease course (mono- or biphasic) and disease severity.
The authors concluded that TBE is a serious disease in southern Norway, and vaccination may be crucial for people living in the TBE endemic area.