[Lyme psychosis].

A woman aged 64 was admitted to the psychiatric department because of a psychotic decompensation with visual hallucinations, disorientation in time and space and associative thinking. On psychotropic drugs the condition failed to improve; subsequently neurological symptoms developed. EEG abnormalities prompted a lumbar puncture. In the CSF a strong plasma cell reaction with atypical cells was observed. The enzyme immunoassay for Borrelia burgdorferi was positive and after treatment with penicillin the psychiatric and neurological signs and symptoms disappeared. From the history which could then be taken it appeared that the patient had been bitten by ticks. Her husband aged 66 years passed through a similar episode of disease.