Lyme-Borreliosis which in Europe is transmitted by Ixodes ricinus presents in three stages with 1st a localised infection (erythema chronicum migrans), 2nd a disseminated infection (e.g., meningoradiculitis), and 3rd a persistent chronic infection (e.g., encephalomyelitis, cerebral vasculitis), whereby not all stages invariably become clinically apparent. The diagnosis is based on the typical clinical presentation, the lumbar puncture (lymphocytic pleocytosis), and serological test from the blood as well as from the CSF (intrathecal antibody production!). The frequency of positive serological results depends on the duration and the type of the disease. In stage 1 20-50% of the patients show increased IgM-antibodies, in stage 2 70-90% show increased IgM- and or IgG-antibodies, and in stage 3 almost 100% of the patients have positive IgG-antibodies. The Lyme-Neuroborreliosis usually is treated with Ceftriaxon 2 g/d intravenously over 14 (Stage 2) or 21 (Stage 3) days.