Lyme disease is a worldwide, tick-transmitted spirochetosis with endemic foci throughout North America, Europe, and Asia. Borrelia burgdorferi is the etiologic bacterium; the vector is a tick of the genus Ixodes.

Lyme disease is now the most common vector-borne illness in the United States. The seasonal pattern of tick activity determines the seasonal pattern of illness onset; symptoms typically begin in late spring or summer. Because ticks prefer forest underbrush, illness is more common in such areas.


Lyme disease begins locally and spreads systemically. Skin, heart, joints, and nervous system are the organ systems most often involved. Illness typically evolves in sequential stages:

Stage Clinical abnormality
Early localized
  • Erythema migrans
  • Regional lymphadenopathy
  • Mild systemic symptoms
Early disseminated
  • Multiple secondary EM
  • Severe systemic symptoms
  • Generalized lymphadenopathy
  • Migratory musculoskeletal pain
  • Myocarditis
  • Pericarditis
  • Polyneuritis
  • Meningitis
  • Early CNS abnormalities
Late disseminated
  • Chronic arthritis
  • Late CNS abnormalities


Stages Table adapted from L Reik. Lyme Disease. In WM Scheld, RJ Whitley, DT Durack (eds), Infections of the Central Nervous System. Philadelphia: Lippincott–Raven, 1997;685–718; DW Rahn, MW Felz. Lyme disease update. Postgraduate Medicine 1998;103:51–70.
Adapted from: Goldstein MA and Harden CL. Infectious states. In: Ettinger AB and Devinsky O, eds. Managing epilepsy and co-existing disorders. Boston: Butterworth-Heinemann; 2002;83-133. With permission from Elsevier (

Authored By: 
MA Goldstein
Cynthia L. Harden MD
Steven C. Schachter, MD
Authored Date: 
Reviewed By: 
Steven C. Schachter, MD
Sunday, February 29, 2004