Scotti M, et al.
Fatal tick-borne encephalitis in an unvaccinated traveler from the United States to Switzerland, 2022. Emerg Infect Dis. 2025;31(11). doi:10.3201/eid3111.251320.
On October 13, 2022, a previously healthy 70-year-old US citizen vacationing in Switzerland sought emergency care after 48 hours of abdominal pain and asthenia. He reported having taken multiple hikes in western Switzerland. His condition rapidly deteriorated neurologically, with the development of ascending paraparesis and additional symptoms. Based on the clinical presentation, cerebrospinal fluid profile, and a positive serum IgM test, tick-borne encephalitis (TBE) was diagnosed. The patient died 16 days after admission, and autopsy findings supported the diagnosis.
Switzerland is a country with a high incidence of TBE. Among the nonvaccinated population, the national incidence is nearly 5 cases per 100,000 persons (Newsletter November 2025). All cantons of Switzerland, except the canton of Ticino, are considered risk areas, and TBE vaccination is recommended throughout the country for persons ≥3 years of age (see Snapshot Week 19/2024).
A similar fatal TBE virus infection acquired in Switzerland by a Serbian resident was described in Snapshot Week 1/2023.
Approximately 20 million tourists visit Switzerland each year, and increasing tourism from non-endemic countries exacerbates the problem of low awareness of TBE-related risks. This case, together with the one discussed in Snapshot Week 1/2023, underscores the importance of personal protective measures and vaccination for travelers to TBE-endemic areas.
In October 2021, the TBE vaccine manufactured by Pfizer (tradename Ticovac) was approved by the US Food and Drug Administration. The Advisory Committee on Immunization Practices published its recommendations for TBE vaccination in 2023 (discussed in Newsletter November 2023).