[Encephalitis following measles-mumps vaccination simultaneous to an EBV-infection (author's transl)].

This is a case-report of a 15-month-old child, who received a measles-mumps vaccination in the course of an asymptomatic EBV-infection. Nine days later the infant incurred encephalitis and recovered substantially within three weeks; the EEG also returned to normal in this time. Ataxia still persisted, however, a half-year later. The child produced serum antibodies against all three viruses, whereby the present low EBNA-titer is indicative of a chronic persistent EBV-infection. This is, according to our knowledge, the first description of a EBV-infection during a measles-mumps vaccination.