Diagnostic Value of RT-PCR for TBEV RNA in CSF
RT-PCR detection of tick-borne encephalitis virus RNA in cerebrospinal fluid identified high-risk TBE cases in Sweden, in practice.
Why RT-PCR in CSF Could Help Diagnose TBE
Tick-borne encephalitis (TBE) is commonly diagnosed using serology, but serologic interpretation can become challenging in patients who have previously received a TBE vaccine. The process may also be complicated in immunosuppressed patients, where immune responses can be altered, delayed, or difficult to interpret clinically.
In this retrospective study, investigators assessed whether RT-PCR detection of tick-borne encephalitis virus (TBEV) RNA in cerebrospinal fluid (CSF) could serve as a complementary diagnostic approach for TBE. They also examined whether TBEV RNA positivity in CSF was associated with clinical characteristics and markers of disease severity.
TBEV RNA in CSF Was Common and Linked to Worse Outcomes
The study included 36 patients with TBE from Region Stockholm and Uppsala, Sweden, between 2015–2020. CSF samples were analyzed using RT-PCR for the presence of TBEV RNA, and clinical information was collected through review of medical records.
TBEV RNA was detected in CSF in 20 of 36 patients (56%). Importantly, patients with detectable TBEV RNA in CSF experienced more severe disease, including higher rates of intensive care admission and the need for assisted ventilation. Across the cohort with detectable TBEV RNA in CSF, mortality was 40%, highlighting a potential association between RT-PCR positivity and poor prognosis.
Immunosuppressed Patients Had Particularly High Fatality Rates
A notable finding emerged in the subgroup receiving immunosuppressive treatment. Among 8 patients with immunosuppression and detectable TBEV RNA in CSF, 7 (88%) had a fatal outcome. Although this subgroup was small, the results suggest RT-PCR positivity in CSF may be particularly meaningful in patients with underlying immune-related comorbidities or immunosuppressive therapy.
Overall, the authors concluded that RT-PCR for TBEV RNA in CSF may be valuable as a complement to standard diagnostics in higher-risk populations. Detectable TBEV RNA in CSF may also correlate with severe infection and an increased risk of fatal outcome, supporting further attention to its potential role in clinical assessment.
Reference: Glans H et al. Diagnostic value of RT-PCR for detection of tick-borne encephalitis virus RNA in cerebrospinal fluid. Eur J Clin Microbiol Infect Dis. 2026; DOI: 10.1007/s10096-025-05389-x.
