A case of fatal hemorrhagic fever associated with tick-borne encephalitis virus infection.

Tick-borne encephalitis virus (TBEV) is a vector-borne orthoflavivirus responsible for monophasic or biphasic disease with central nervous system manifestations. A middle-aged, severely immunocompromised woman became gradually more febrile after a forest hike. She was admitted to the hospital with thrombocytopenia, leukopenia, and elevated liver enzymes, as well as ecchymosis on the truncus. During her hospitalization, she experienced repeated severe hemorrhages from different retroperitoneal blood vessels. Despite successful embolization of the bleeding vessels, she died in circulatory shock due to compression of the inferior vena cava from large retroperitoneal hematomas. Autopsy did not reveal any sign of encephalitis. TBEV was detected in blood plasma and cerebrospinal fluid by polymerase chain reaction. Whole genome sequencing demonstrated clustering with the Kumlinge A52 isolates from Finland, a variant of European TBE.