Acknowledgment
This report is published on behalf of the GeoSentinel Office of the Principal Investigator. GeoSentinel is a cooperative agreement U01CK000632-01-00 between the US Centers for Disease Control and Prevention (US CDC) and the International Society of Travel Medicine (ISTM).
Author
Stephen D. Vaughan, MD DTM&H CTropMed FRCPC
Associate Professor, Clinical | Infectious Diseases and Tropical Medicine Consultant
Alberta Health Services – Calgary Zone and Cumming School of Medicine, University of Calgary, Canada
Summary
A 70-year-old man was diagnosed with tick-borne encephalitis virus (TBEV) infection, confirmed by PCR from blood with subsequent seroconversion, and a positive European Lyme immunoblot.
Travel history
The patient traveled to Czechia (Telč) from 5 Aug to 6 Oct 2025, with a side trip to Tbilisi, Georgia (4–10 Sep 2025). There was no known tick bite.
Initial presentation and hospital course
Symptoms started on 1 Oct 2025 with subjective fever and confusion. He sought care in Calgary, Canada, on 7 Oct 2025, where broad-spectrum antibiotics were started. Pancytopenia quickly improved with granulocyte colony-stimulating factor (G-CSF), antibiotics, and temporary discontinuation of upadacitinib (Rinvoq) for Crohn’s disease. The highest recorded temperature was 38.9°C on 7 Oct. CT scan of the head showed no acute findings; MRI and lumbar puncture were not done because there were no signs of meningeal involvement. He was discharged from the hospital on 11 Oct with temporary improvement in confusion.
Post-discharge course and diagnostic testing
Fever recurred with severe night sweats three days after discharge. He was seen as an outpatient and started empirically on doxycycline while awaiting diagnostic results. Due to ongoing mild confusion, TBEV testing was added to previously collected samples and came back positive. Initial (acute) testing showed negative TBEV IgM and IgG but positive serum PCR; later testing confirmed TBEV IgM and IgG seroconversion with negative serum PCR. After the European Lyme immunoblot tested positive, the doxycycline course was extended to 28 days for potential concurrent neuroborreliosis. The European test specifically detects antibodies to antigens from European Borrelia species, such as B. garinii and B. afzelii. On follow-up, the patient had returned to his neurological baseline.
Discussion
- This case illustrates travel-related TBEV infection acquired in a high-incidence Central European country (Czechia) with a possible concurrent neuroborreliosis, in an immunosuppressed, unvaccinated older adult. TBE is endemic throughout Czechia, and the country consistently reports some of the highest TBE incidence rates in Europe. Circulation of TBEV in Georgia and the South Caucasus has also been documented, although comprehensive, long-term incidence data have not been published.
- In many parts of Europe, Lyme disease and tick-borne encephalitis are both common and transmitted by the same vector (Ixodes ricinus), so co-infections can happen in patients exposed in these regions. Clinicians should therefore routinely consider and, when appropriate, test for both TBEV and Borrelia in travelers returning with compatible neurological or systemic symptoms after tick exposure in endemic areas.
- The lack of a licensed TBE vaccine in Canada and other non-European countries emphasizes the importance of proactive, detailed pre-travel counseling on TBE risks for travelers heading to highly endemic areas. This should include discussing options for vaccine access (such as vaccination in Europe or other places where TBE vaccines are available, if possible), emphasizing personal protective measures against tick bites, and noting that immunosuppressed and older travelers may face higher risks of severe illness.
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FAQ
Acknowledgment
This report is published on behalf of the GeoSentinel Office of the Principal Investigator. GeoSentinel is a cooperative agreement U01CK000632-01-00 between the US Centers for Disease Control and Prevention (US CDC) and the International Society of Travel Medicine (ISTM).
Author
Stephen D. Vaughan, MD DTM&H CTropMed FRCPC
Associate Professor, Clinical | Infectious Diseases and Tropical Medicine Consultant
Alberta Health Services – Calgary Zone and Cumming School of Medicine, University of Calgary, Canada
Summary
A 70-year-old man was diagnosed with tick-borne encephalitis virus (TBEV) infection, confirmed by PCR from blood with subsequent seroconversion, and a positive European Lyme immunoblot.
Travel history
The patient traveled to Czechia (Telč) from 5 Aug to 6 Oct 2025, with a side trip to Tbilisi, Georgia (4–10 Sep 2025). There was no known tick bite.
Initial presentation and hospital course
Symptoms started on 1 Oct 2025 with subjective fever and confusion. He sought care in Calgary, Canada, on 7 Oct 2025, where broad-spectrum antibiotics were started. Pancytopenia quickly improved with granulocyte colony-stimulating factor (G-CSF), antibiotics, and temporary discontinuation of upadacitinib (Rinvoq) for Crohn’s disease. The highest recorded temperature was 38.9°C on 7 Oct. CT scan of the head showed no acute findings; MRI and lumbar puncture were not done because there were no signs of meningeal involvement. He was discharged from the hospital on 11 Oct with temporary improvement in confusion.
Post-discharge course and diagnostic testing
Fever recurred with severe night sweats three days after discharge. He was seen as an outpatient and started empirically on doxycycline while awaiting diagnostic results. Due to ongoing mild confusion, TBEV testing was added to previously collected samples and came back positive. Initial (acute) testing showed negative TBEV IgM and IgG but positive serum PCR; later testing confirmed TBEV IgM and IgG seroconversion with negative serum PCR. After the European Lyme immunoblot tested positive, the doxycycline course was extended to 28 days for potential concurrent neuroborreliosis. The European test specifically detects antibodies to antigens from European Borrelia species, such as B. garinii and B. afzelii. On follow-up, the patient had returned to his neurological baseline.
Discussion