– A multisystem infectious disease transmitted by a tick bite and characterized by an early skin lesion.

Causes and Incidence

The disease is caused by a spirochete called Borrelia burgdorferi. Lyme disease is the most common vector-transmitted disease in the United States. People of all ages are vulnerable, and the highest incidence is among individuals living in and around wooded areas.

Disease Process

The spirochete enters the skin at the site of a tick bite. It incubates for 3 to 32 days, then migrates outward to the skin and forms a pinkish red rash that resembles a bull’s-eye target. It may then spread to other skin sites and various organ systems via the lymphatics and bloodstream. An inflammatory cycle is set up, and cardiac, neurologic, and joint abnormalities are common developments.


The disease first manifests itself as a red skin macule or papule at the bite site with accompanying flulike symptoms. These are often missed or ignored by the individual. In about 50% of cases, other lesions develop soon after onset.

Potential Complications

After weeks or months, neurologic abnormalities such as meningitis, meningoencephalitis, neuritis, and radiculopathies appear in about 15% of cases. Myocardial abnormalities such as atrioventricular block, myopericarditis, and cardiomegaly occur in 8% of cases. Joint inflammation, pain, and arthritis develop in 50% of cases as long as 2 years after transmission.

Diagnostic Tests

A physical examination with characteristic lesions and a positive enzyme-linked immunosorbent assay (ELISA) is indicative of the disease.



Antiinfective drugs to combat infection.

Bed rest; treatment of complications; prevention by wearing appropriate clothing in wooded or grassy areas and using bug repellent.