Lyme disease: clinical manifestations, diagnosis, and treatment.

Lyme disease, caused by the spirochete Borrelia burgdorferi, is the most common vector-borne disease in the United States. The causative organism is transmitted through cutaneous inoculation by infected ixodid ticks. Illness typically begins in the summer with the characteristic skin rash, erythema migrans, and associated flulike symptoms. Weeks to months later, the majority of untreated individuals experience one or more manifestations of disseminated Lyme disease, primarily involving the nervous system, heart, and joints. Diagnosis is based on recognition of the appropriate signs and symptoms in the setting of travel to or residence in an endemic area, and supported by serological testing. All stages of the illness are responsive to antibiotics, although treatment is more efficacious when begun early in the course of Lyme disease.