Late complaints after erythema migrans Herta Klade, MD and Elizabeth Aberer, MD. JSTD 1994; 1:52-56. A lot of treatment studies have been carried out, but no antibiotic has been proved to avoid late manifestations of Lyme disease. Our interest focused on late manifestations following20uncomplicated erythema migrans, UEM, and complicated erythema migrans, CEM, after a median observation period of 30 months. To compare the therapeutic, serological, and clinical outcome, 161 patients were re-examined prospectively. Late complaints could be observed in 31/161, 19%, of patients, more often in CEM than in UEM, 36% versus 12%. Patients with late sequelae were more often seropositive than the total collective, 77% versus 67%, at least once during the observation period, as against 12 of 13 patients who needed several therapy cycles, 92%. Seven seropositive patients did not respond to oral antibiotic treatment even after several cycles. Amoxicillin/clavulanic acid treated patients had late complaints in 8% in contrast to penicillin V, 15%, and doxycycline, 17%, treated persons. Seropositivity before treatment has a negative influence on the course of erythema migrans, EM, disease. Immunogenetic disposition might be responsible for repeated infections and for treatment failures in a certain patient group