Epidemiological study of a cohort of adult patients with Erythema migrans registered in Slovenia in 1993.

Epidemiological characteristics of 892 adult patients with typical Erythema migrans (Em), registered at Lyme borreliosis Outpatients' Clinic, Department of Infectious Diseases, University Medical Centre Ljubljana, Slovenia, in 1993, are presented. Data were gathered prospectively by means of a questionnaire. All the patients were seen by at least one of the four authors of this report. There were 57% females and 43% males aged from 15 to 91 years (median value 44 years, mean 44.4 +/- 14.3 years). The highest number of patients was found in age groups from 30 to 59 years. 73% of the patients quoted a tick bite at the site of later Em and 6% an insect bite; 21% didn't remember any bite. 212 out of 638 patients with a tick bite were able to assess the maximal possible duration of tick attachment: two-thirds quoted 24 hours or less. Interval from a tick bite to the appearance of skin changes was one day to six months (median value 15 days, mean 20.3 +/- 20.6 days) and from the beginning of Em to registration one day to 10 months (median value eight days, mean 17.1 +/- 24.2 days). More than half of the patients were registered in June, July and August. The majority of patients with Em resided in the region of Ljubljana. They were bitten by ticks predominantly near their homes but some of them also quite far away. Slovenia is an endemic region for Lyme borreliosis. The number of cases presented in our report is most likely only a fraction of the real number of patients with Em in the region of Ljubljana and is even further underestimated for other parts of Slovenia.