[The difficulties of clinical diagnosis of mixed-infection of tick-born encephalitis and Lyme disease].

The authors report 49 cases of mixed infection (Lyme disease + tick-born encephalitis). All the patients were citizens of the Russian North-West. Clinically, there were symptoms of Lyme disease (erythema) and tick-born encephalitis (serous meningitis, neuritides of the cranial and peripheral nerves). In patients with mixed infection in the presence of erythema symptoms of tick-born encephalitis were less evident. The diagnosis of Lyme disease erythema-free form in combination with tick-born encephalitis may be made only by dynamic serological tests for both of these infections.