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Lyme disease - erythema migrans

Lyme disease - erythema migrans

Overview

Erythema migrans is the initial lesion of Lyme disease, and often appears at the site of the infecting tick bite. It is a red, enlarging rash, flat or slightly raised, and may reach from 4 to 20 inches (12 to 35 cm) across (the average rash is 6 inches, or 17 cm). (Image courtesy of the Centers for Disease Control and Prevention.)

Review Date 3/16/2024

Updated by: Jatin M. Vyas, MD, PhD, Associate Professor in Medicine, Harvard Medical School; Associate in Medicine, Division of Infectious Disease, Department of Medicine, Massachusetts General Hospital, Boston, MA. Also reviewed by David C. Dugdale, MD, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team.