Tick-borne Encephalitis in International Travelers: A Systematic Review and Vaccine Recommendations

Abstract Background Tick-borne encephalitis (TBE) is a potentially life-threatening infectious disease caused by the tick-borne encephalitis virus (TBEV). In recent years, TBE endemic areas have expanded in Europe and the incidence of surveillance-reported TBE cases has increased. TBE is preventable through vaccination, with vaccines available and recommended for residents of, and travelers to, TBE endemic regions. We summarized the published literature on international travel-associated TBE cases and country-specific TBE vaccine recommendations for travelers. Methods We conducted a systematic literature review using PubMed and Web of Science and reviewed public health surveillance online sources to identify reports of travel-associated TBE cases published from 1978 to 2024. We also analyzed the European Centre for Disease Prevention and Control (ECDC) TBE Annual Epidemiological Reports from 2015 to 2022 for travel-associated cases and collected information on TBE vaccination recommendations by national public health authorities for travelers to Europe. Results Thirty-nine international travel-associated TBE cases were identified from 24 articles and one public health report. Of the 34 travel-associated TBE cases with clinical information, 33 (97.0%) were hospitalized for a median of 9 days. Travel-associated cases departed from the United States, Israel, and several countries in Europe; most frequently visited countries were Austria, Russia, Sweden, and Switzerland. Of the 22,191 surveillance-reported TBE cases reported to ECDC from 2015 to 2022, 376 (1.7%) were international travel-associated cases. Recommendations for TBE vaccination for travelers were identified in 32 countries. Conclusions Despite recommendations for TBE vaccination for travelers to TBE endemic areas in Europe, international travel-associated TBE cases among travelers to Europe continue to occur. Most of the published travel-associated TBE cases are associated with severe clinical illness. When considering the increasing geographic spread of the TBE endemic areas and increasing TBE incidence in Europe, enhanced efforts are needed to inform appropriate international travelers about the risk of TBE and to promote vaccination of travelers to TBE endemic areas in Europe.