A woman in her 60s, farmer, presented with an asymptomatic abdominal erythema that had been expanding for 5 days. She denied having fever, headache, arthralgias, or myalgias. On examination, a nontender, 18 cm in diameter, annular erythematous lesion with central clearing and a tick attached in the middle of the ring, consistent with erythema migrans (EM) was noted (Figure 1A). The tick was identified as Ixodes ricinus on dermatoscopy (Figure 1B). The Borrelia burgdorferi antibody test (Western blotting) showed an increased serum anti-Borrelia IgM levels. These findings confirmed the diagnosis of Lyme borreliosis. The tick was removed using a small forceps. Doxycycline 200 mg/day/was prescribed for 14 days, and EM cleared after 7 days.

Lyme borreliosis (LB) is a vector-borne disease caused by Borrelia burgdorferi spirochetes, found in Europe, North America, and Asia. The tick Ixodes ricinus is the dominant vector in Europe while the Ixodes scapularis is the principal vector of B. burgdorferi in North America [1]. Ticks contract B. burgdorferi from infected rodents, birds, and deer. Early LB signs include EM, appearing in over 70% of cases within a month of a tick bite. Spring and early summer infections are common, but climate change reshapes LB dynamics, expanding tick habitats and extending activity seasons due to warmer temperatures. Ticks can feed on any part of the body, often going unnoticed due to painlessness. A tick must be attached for 36-48 hours to transmit Borrelia. EM is usually solitary, yet 10%-20% of patients present multiple lesions, resulting from hematogenic bacterial spreading. While ticks are attached, an erythematous lesion might indicate hypersensitivity reaction, distinct from EM. Hypersensitivity lesions are less than 5 cm, non-expansive, and tends to resolve within two days [2]. Single EM cases require antibiotic treatment (e.g., oral doxycycline for 10-21 days) to prevent later complications such as carditis, neuroborreliosis, or arthritis [3].