|Description:||This image depicts the posterior knee, or popliteal region of a patient’s right leg who’d presented with the erythema migrans (EM) rash characteristic of what was diagnosed as Lyme disease, caused by the bacterium, Borrelia burgdorferi.|
B. burgdorferi bacteria are transmitted to humans through the bite of infected blacklegged ticks. Typical symptoms include fever, headache, fatigue, and a characteristic skin rash called erythema migrans. If left untreated, infection can spread to joints, the heart, and the nervous system.
Erythema migrans (EM) or "bull's-eye" rash
- Rash occurs in approximately 70-80% of infected persons1 and begins at the site of a tick bite after a delay of 3-30 days (average is about 7 days).
- Rash gradually expands over a period of several days, and can reach up to 12 inches (30 cm) across. Parts of the rash may clear as it enlarges, resulting in a “bull's-eye” appearance.
- Rash usually feels warm to the touch but is rarely itchy or painful.
- EM lesions may appear on any area of the body.