Tick-borne encephalitis.

Abstract

Tick-borne encephalitis (TBE) is an important central nervous system infection in Europe and Asia. It is caused by three subtypes of TBE virus (TBEV): European, Siberian and Far-Eastern, belonging to the genus Flavivirus. TBE is delineated by three criteria: the presence of clinical signs of meningitis, meningoencephalitis or meningoencephalomyelitis; cerebrospinal fluid pleocytosis (>5 × 106 cells/L); and demonstration of a recent infection with TBEV by the presence of specific serum IgM and IgG antibodies or IgG seroconversion. Imaging of the brain and spinal cord has a low sensitivity and specificity, but it is useful for the differential diagnosis. Clinical course and outcome of TBE depend on the subtype of TBEV (the disease caused by the European subtype has a milder acute course and a more favorable long-term outcome than the disease caused by the other two virus subtypes), age of patients (increasing age is associated with more severe acute course and poorer outcome) and probably on some host genetic factors. Due to relatively severe clinical course combined with the absence of etiologic treatment, considerable proportion of patients with incomplete recovery after acute illness, and increasing incidence, TBE represents a growing (public) health problem that could be substantially reduced with vaccination.