Lyme Disease

Lyme disease is caused by the bacterium Borrelia burgdorferi and is transmitted to humans by the bite of infected blacklegged ticks.

Typical symptoms include fever, headache, fatigue, and a characteristic skin rash called erythema migrans. If left untreated, the infection can spread to joints, the heart, and the nervous system.

Lyme disease is diagnosed based on symptoms, physical findings (such as a rash), and the possibility of exposure to infected ticks; laboratory testing is helpful in the later stages of disease.

Most cases of Lyme disease can be treated successfully with a few weeks of antibiotics. Steps to prevent Lyme disease include using insect repellent, removing ticks promptly, landscaping, and integrated pest management.

The ticks that transmit Lyme disease can occasionally transmit other tick-borne diseases as well.

What Does the Rash of Lyme Disease (Erythema Migrans) Look Like?

A key component of early diagnosis is recognition of the characteristic Lyme disease rash called erythema migrans (EM). This develops at the site of the tick bite in about 80% of Lyme disease patients about 3 to 30 days following the tick bite.

Typically, the rash expands over a period of several days, reaching up to 12 inches (30 cm) across. The center of the rash may clear as it enlarges, resulting in a bull's-eye appearance. It may be warm but is not usually painful. Some patients develop additional EM lesions in other areas of the body after several days. Patients also experience symptoms of fatigue, chills, fever, headache, and muscle and joint aches, and swollen lymph nodes. In some cases, these may be the only symptoms of infection.

What Are the Symptoms of Lyme Disease?

Lyme disease can infect several parts of the body, producing different symptoms at different times. Not all patients with Lyme disease will have all symptoms, and many of the symptoms can occur with other diseases as well. If you think you may have Lyme disease, it is important that you consult your doctor as soon as possible for proper diagnosis.

Most cases of Lyme disease can be cured with antibiotics, especially if treatment is begun early in the course of illness. However, a small percentage of people with Lyme disease have symptoms that last months to years after treatment with antibiotics. These symptoms can include muscle and joint pains, arthritis, cognitive defects, sleep disturbance, or fatigue. The cause of these symptoms is not known. There is some evidence that they result from an autoimmune response, in which a person's immune system continues to respond even after the infection has been cleared.