Clinical study of erythema migrans

Background: Lyme disease, an infection caused by Borrelia(B.) burgdorferi, has been reported in many countries. But in Korea, only 5 cases of serologically diagnosed lyme disease have been reported. Because several strains of B. burgdorferi were isolated from Ixodes ticks which were captured in Kangwon and Chungbuk province, there might be more cases of serologically undiagnosed lyme diseases presenting with erythema migrans. Objective: To understand the clinical patterns and laboratory findings of erythema migrans in Korea. Methods: A clinical survey was retrospectively performed on 9 patients with erythema migrans which occurred after tick bites. Results: Among 9 patients with erythema migrans, 3 patients were male and 6 patients were female. The onset age of erythema migrans ranged from 26 to 71 years old (mean, 51.3 years old). The mean duration of erythema migrans after tick bite was 26.4 days and the diameter of the lesion ranged from 6 to 34 cm (mean, 18.3 cm). All cases developed from May to September and systemic symptoms such as fatigue, fever and/or chills, myalgia, palpitation, headache, arthralgia and dyspnea were present at the time of hospital visits of 3 patients. Clinically, 3 patterns of erythema migrans were seen; typical target pattern, homogenous and erythematous plaque pattern, and linear solitary plaque pattern with central postinflammatory pigmentation. Only 2 of the 7 patients (28.6%) were seropositive for IgM and IgG antibody titers by enzyme-linked immunosorbent assay in consecutive serologic tests. PCR for Borrelia DNA in paraffin-embedded tissue showed full negativity in 6 patients with erythema migrans. Conclusion: Although lyme disease is not endemic in Korea, some patients with erythema migrans might be undiagnosed as lyme disease serologically with erythema migrans. To take into consideration false negative serologic results in early erythema migrans, early oral tetracycline therapy should be included through clinical and historical diagnosis.