Most cases of Lyme disease in the US occur between May and September in the Northeastern, Mid-Atlantic, and North Central states.
Lyme disease in the US is caused by the spirochete Borrelia burgdorferi, which is transmitted to humans by Ixodes scapularis or I pacificus ticks.1 The characteristic skin lesion, erythema migrans, develops at the site of the tick bite 1-2 weeks after the tick has detached (range 3-30 days) and expands over days to weeks. The classic skin lesion has central clearing with a bull’s-eye appearance, but more often the rash is homogeneously erythematous and, rarely, necrotic or vesicular. Erythema migrans may go unnoticed because it often occurs in areas not readily visible to the patient, such as the back, buttocks, axillae or popliteal fossa, is often asymptomatic, and resolves spontaneously within weeks.