Erythema migrans (Lyme borreliosis).: Clinicoepidemiological characteristics in 50 patients

Background and objective. Erythema migrans (EM) is the earliest and most common manifestation of the infection caused by B. burgdorferi (Lyme borreliosis). The objective of the present work was to report the clinicoepidemiological features in a series of patients, Patients and methods. Retrospective collection of clinicoepidemiological features of the first fifty patients diagnosed of EM at La Rioja Hospital (March 1989-September 1998). Results. In our series, no differences were observed regarding sex or living in a rural or urban area. Mean age was 41 years (range 9 to 78). In 70% of patients the antecedent of a tick bite was obtained and the incubation period was 6.48 days (1 to 15 days). The mean size of the lesions was 14.3 cm (5 to 40) and in 16% of patients satellite cutaneous lesions were observed. The areas where EM appeared were lower limbs and the perineal region (60%), chest (24%), head and nock (10%) and upper limbs (6%). Forty-eight percent of patients reported extra-cutaneous manifestations. All cases occurred during the spring, summer and autumn months, with a peak in June. The most common referred antecedent was walking in forest areas. All patients responded to antibiotic therapy. Conclusions. EM is common in the studied environment and presents with a marked polymorphism.