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Lyme borreliosis is endemic in Slovenia. Its incidence has been on the increase over the past decade, and is among the highest in Europe. Erythema migrans is the clinical hallmark of Lyme borreliosis. It is estimated that this sign is present in approximately three-quarters of patients during the early course of the disease. Typical erythema migrans is the only clini­cal finding that enables a reliable diagnosis of Lyme borreliosis. The presence of erythema migrans alone is a sufficient indicator for the initiation of antibiotic therapy, which is espe­cially efficient early in the course of the disease.

This study presents clinical and epidemiological findings in adult patients with erythe­ma migrans who were diagnosed at the Lyme Borreliosis Outpatient Clinic, Department of Infectious Diseases, University Medical Center, Ljubljana in 2000. These findings were com­pared with data obtained using the same approach for an identical group of patients in 1993.

It was expected that the knowledge base on Lyme borreliosis would be superior in 2000 compared to 1993; it was also hypothesized that patients would visit the Clinic earlier in the course of the disease, and consequently present with smaller skin lesions and fewer systemic complaints.

The study was prospective. Patients who qualified for inclusion in the study were at least 15 years of age, diagnosed with typical erythema migrans in 1993 and 2000 at the Lyme Borreliosis Outpatient Clinic in Ljubljana. The diagnosis of erythema was established clini­cally according to the modified criteria proposed by the CDC (Centers for Disease Control). Epidemiological and clinical data were acquired by means of a questionnaire. Differences in quantitative data were analyzed using the Kruskall-Wallis test, and differences in quali­tative data by χ-square test or Fisher’s exact test.

Five hundred and thirty-five patients were included in the study in 2000, of whom 309 (57.8%) were female and 226 (42.2%) male, aged from 15 to 80 years (median age was 47). Three hun­dred and eleven (58.1%) patients recalled atick bite at the site of later erythema. 55.7% of patients presented with erythema on the lower extremity, 14 days (median) after a tick bite. At the time of diagnosis, the average affected skin area was 75 cm² and the largest diameter ranged from 2 to 87 (median 12) cm. The median duration of erythema prior to diagnosis was 8.5 days. Thirty-six of the 535 (6.7%) patients presented with multiple skin lesions. 52.2% of patients reported local symptoms, and 35.7% had systemic complaints. In 1993, 889 patients with typical erythema migrans were diagnosed. Compared to the cohort of patients with erythema migrans registered in 2000, the patients from 1993 were younger (44 versus 47 years, p = 0.025), recalled a tick bite more often (p = 0.049) and presented with smaller erythema upon diagnosis (50.2 versus

75.0 cm², p = 0.025). Patients in 1993 visited the clinic earlier than in 2000 (8 versus 8.5 days, p = 0.352), but had systemic symptoms more frequently (41.2% versus 35.7%, p = 0.033).

The majority of findings for the two cohorts of patients with erythema migrans seen in 1993 and in 2000 were comparable; however, our hypothesis was not confirmed. Patients in 2000 did not visit the Clinic earlier, and had larger diameters of erythema at the time of their visit. Nevertheless, they did report systemic symptoms less frequently.