Overview
Lyme disease is caused when a person is bitten by a tick infected with bacteria called Borrelia burgdorferi. These bacteria are known as spirochetes because of their long, corkscrew shape. This photograph shows the typical corkscrew appearance of a spirochete. Other types of spirochete bacteria cause diseases such as syphilis and leptospirosis. After a person is bitten by an infected tick, the bacteria spread from the skin through the bloodstream to other organs. The skin, nervous system, joints, heart, and eyes are most often affected. (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.