Tick-borne encephalitis (TBE) is a neurotrophic viral
disease which is endemic to certain regions. Such areas in Germany include Bavaria, Baden-Württemberg, and the Odenwald region in Hessen. So far, it has not been endemic to Rhineland-Palatinate. There, only two single cases of TBE occurred in the years 1992 and 1997, near the town of Idar-Oberstein. We report two new cases of TBE which appeared in 1999 and two current cases from the Idar-Oberstein region which have been verified clinically and serologically. At admission, the patients suffered from headache, muscle pains, and high fever, in one case meningitis was suspected. In all four patients, serology for borrelia was negative in serum and CSF. The described cases indicate that it is possible to acquire TBE in Rhineland-Palatinate, although only two cases have been reported in this area over the previous 10 years. Particularly in regions with a low incidence of TBE, the
disease should be taken into consideration as a differential diagnosis. Studies of tick populations in regions with a low incidence can help in evaluating the benefit of possible vaccine recommendations by local public health authorities.