Background: The clinical manifestations of Lyme borreliosis in North America and Europe seem to differ, but a systematic comparison has never been done.
Objective: To compare European and U.S. patients with culture-confirmed erythema migrans.
Design: Prospective, clinical cohort study.
Setting: University medical centers in Westchester County, New York, and Ljubljana, Slovenia.
Patients: 119 U.S. patients with Borrelia burgdorferi sensu stricto infection and 85 Slovenian patients with B. afzelii infection.
Measurements: Interview, physical examination, and laboratory assays.
Results: Compared with Slovenian patients, U.S. patients had erythema migrans for a briefer duration (median duration, 4 days compared with 14 days; P < 0.001) but were more likely to have systemic symptoms (P = 0.01), abnormal findings on physical examination (P < 0.001), and seroreactivity (P < 0.001). Central clearing of erythema migrans lesions was more likely in Slovenian patients (P < 0.001).
Conclusions: Erythema migrans caused by B. afzelii in Slovenia and erythema migrans caused by B. burgdorferi in New York have distinct clinical presentations. Caution should be used when clinical and laboratory experience from one side of the Atlantic is applied to patients on the other.