60–70 % of Lyme borreliosis is formed by early manifestations, in particular erythema migrans (EM). All vegetative forms of the tick Ixodes ricinus (e.g. full grown tick, nymphae and larvae) transmit the causal organism, the spirochete Borrelia burgdorferi sensu stricto and Borrelia burgdorferi sensu lato (B. garinii, B. afzelii). The objective of the work was to evaluate clinical and epidemiolo- gical parameters and to contribute by testing and investigating in greater detail criteria to the early and exact diagnosis of the disease. In a group of 50 patients the time of development of EM was evaluated, the mode of transmis sion, the incubation period, localization, symptoms of dissemination of B. burgdorferi, the period of treatment and the antibiotic used. The dynamics of the antibody titre against B. burgdorferi (IFA test) were assessed in 21 patients with EM for a period of 1 to 22 months and in 5 patients with acrodermatitis chronic atrophicans (ACA) for 3 to 55 months. In 50% EM developed during the summer months. 66% reported as the vector a tick, 14% insects and 20% did not know. An incubation of 1 and 2 weeks was reported in 34%, the lower extremities were affected in 52%. Manifestations of dissemination were found in 6 patients, in 2 patients EM relapsed. Antibodies (Ab) against B. burgdorferi were present in 38 patients. In 21 patients the dynamics of the antibody titre were followed up for 1 to 22 months and no substantial changes were found. Serum positivity in patients with ACA persisted without change of the titre for several years. In the treatment of EM most frequently doxycycline was administered for two weeks.EM as the early stage of LB is a seasonal disease with a natural focus. If treatment is started in the early stage of infection, antibodies against B. burgdorferi need not develop. There is no correlation between clinical complaints and serological results and the type of treatment. The prognosis of the disease is favourable in the majority of patients. Vaccination offers new possibilities in active protection against Borrelia infection, in particular in endemic areas. For European countries at present a recombined vaccine is being prepared from the surface lipoprotein A (OspA) made from prevalent strains of B. afzelii and B. garinii.

        Key words: Lyme borreliosis – erythema migrans – acrodermatitis chronica atrophicans – Borrelia