Lyme Disease

Lyme disease is caused by an infection carried by ticks. The illness is named after the town of Old Lyme, Connecticut, where the first cases were found in 1975.


The first sign of Lyme disease is usually a growing skin lesion where the tick bit. There may also be fever, muscle and joint pain, headaches and other skin lesions. Without antibiotics early, the illness may involve the heart, nervous system, joints and other organs.

Causes and Risk Factors

An organism called a spirochete causes Lyme disease. The infection is spread through the bite of a tiny infected tick. In the United States, this tick is found mainly in three areas: the coastal Northeast, the upper Midwest (where the carrier is the deer tick) and in coastal California (where the carrier is the western black-legged tick).


Lyme disease is diagnosed on the basis of the symptoms in people who could have been exposed to infected ticks. After four weeks, individuals with the illness usually have abnormal blood tests. However, a negative test does not completely exclude the disease. A positive test alone does not confirm a diagnosis.


Early on the disease generally responds to oral antibiotics but may require intravenous therapy. Therapy can last from 10 days to four weeks. Some symptoms may continue after treatment. After observation, unresolved symptoms may require additional treatment.

Some people with late neurologic or arthritic conditions may not improve even after treatment with antibiotics.