Lyme Disease Overview

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BlackleggedTick Lyme Disease
Lyme disease is caused by infection with the tick-borne spirochete (a type of bacteria) Borrelia burgdorferi. Early symptoms may include an expanding red rash (called erythema migrans), fatigue, chills, fever, headache, muscle and joint aches, and swollen lymph nodes, among others. Untreated infections may progress to affect the joints, heart, and nervous system. Infection in humans is typically divided into three stages: early disseminated stage, late disseminated stage, and, in a small percentage of people, post-treatment Lyme disease syndrome. The latter two stages may or may not occur, depending on successful treatment and other factors. These stages may overlap clinically, but can also occur independently, with apparent recovery between stages.

Lyme disease was named after the town of Lyme, Connecticut, where it was first described in 1976, and it is now by far the most frequently diagnosed tick-borne disease in the country. The vast majority of human cases occur in the northeastern and north-central regions of the U.S., with most infections occurring in the spring and summer. The Lyme disease bacterium is transmitted by the blacklegged tick (Ixodes scapularis) in the northeastern, mid-Atlantic, and north-central United States and the western blacklegged tick (Ixodes pacificus) on the Pacific Coast.

A rash similar to the rash of Lyme disease has been described in humans following bites of the lone star tick, Amblyomma americanum, a tick very common in Texas. The rash may be accompanied by fatigue, fever, headache, and muscle and joint pains. This condition has been named southern tick-associated rash illness (STARI). The cause of STARI is not known. In the cases of STARI studied to date, the rash and other symptoms have resolved following treatment with an oral antibiotic, but it is unknown whether this medication speeds recovery.

Monitor your health closely after any tick bite, and talk to your health care provider if rash, fever, headache, muscle or joint pains, or swollen lymph nodes develop within 30 days of a tick bite. These can be signs of a number of tick-borne diseases.