SWEtick - a Prospective Multicenter Study of Tick-borne Diseases in Sweden

1. Medical history: tick exposure, tick bite, splenectomy, immunosuppressive treatment (e.g. anti-CD20 or other biological/immunomodulatory drugs, cortisone corresponding to \>10 mg prednisolone/day, chemotherapy, hematologic malignancy, other malignancy, rheumatologic disease) 2. Symptoms/clinical signs: fever after tick bite, relapsing fever of unknown origin, skin rashes (single/multiple erythema migrans, lymphocytoma, acrodermatitis chronica atrophicans or other), venous thrombosis, repeated thrombophlebitis, meningitis, encephalitis, myelitis, cranial nerve palsy, radiculitis, peripheral nerve involvment, mono-/oligoarthritis, carditis, ocular or otogenic disturbances of uncertain origin where medical history includes recent tick bite. 3. Biochemical findings in combination with factors under a) and b): leukopenia, thrombocytopenia, anemia, elevated liver enzymes, slightly elevated erythrocyte sedimentation rate and/or C-reactive protein, pleocytosis in CSF or synovial fluid.