Borrelia meningitis in Denmark.

We studied 23 patients with borrelia meningitis, a tick-borne spirochetosis increasingly recognized in Denmark. The disease showed a seasonal incidence from June to December. Twenty one patients experienced a painful sensory radiculitis, in 17 cases followed by a predominantly cranial mononeuritis multiplex mainly affecting the facial nerve (Bannwarth's syndrome). Three patients had focal CNS involvement in the form of a transverse myelitis, a focal encephalitis and a disseminated leucoencephalopathy, respectively. The CSF showed invariably lymphocytic pleocytosis and elevated spinal protein concentration. Measuring borrelia antibodies in the CSF seemed of higher diagnostic sensitivity than in serum. Penicillin therapy was effective even in cases with focal CNS lesions.