Infection results in cutaneous eruption, known as erythema chronicum migrans, at the site of the bite. The spirochete may stay localized to the skin or may spread hematogenously from the site of inoculation and involve other areas of the skin or the heart, peripheral and central nervous systems, joints, or other organs. Erythema migrans is the cutaneous hallmark of Lyme disease. The clinical picture varies from barely detectable erythema to brightly erythematous, annular patches or plaques. The lesions may be slightly scaly and have central clearing, giving them a targetlike appearance.
Some patients report a burning or stinging sensation within the lesions.
The rash usually fades in about 4 weeks but reportedly can last up to 14 months. Regional lymphadenopathy may be present. Early treatment is necessary in all cases of Lyme disease to prevent development of systemic sequelae. The diagnosis of Lyme disease is based on clinical history and objective findings on examination. Careful history taking is vital.