Erythema Migrans

Key Points
Erythema migrans is the rash associated with Lyme disease (discussed below).
Bacterial infection which affects the skin, heart, joints, eyes, and nervous system
Caused by infection with borrelia burgdorferi, which typically results from a tick bite
Consists of a red rash surrounding the bite, which may spread to other areas and be accompanied by various symptoms

Erythema migrans is the rash associated with Lyme disease.

Lyme disease is a bacterial infection which can affect the skin, heart, joints, eyes and nervous system. Initial cutaneous presentation in the first stage of development consists of a red rash at the site of infection, which may remain clear. The rash, referred to as erythema migrans, appears approximately a week after infection, and may be accompanied by fever, swollen lymph glands in the affected area, chills, joint pain, and fatigue, which may disappear and reappear as the disease progresses. The second stage of development, in which the infection disseminates into the bloodstream, sees erythema migrans appear on other parts of the body, continued symptoms from the localized stage accompanied by stiff neck, tingling/numbness in the extremities, sore throat, facial paralysis, and changes in vision. This stage may continue for years if undiagnosed. Late stage Lyme disease causes arthritis in the large joints, neurological disorders, and numbness spreading into the arms and legs from the extremities.

Lyme disease is typically caused when the affected person is bitten by an infected tick, the Ixode tick, which often live on deer. The bacteria which causes the infection is borrelia burgdorferi. In certain areas of the US, the condition is common, but does occur in other areas. Not everyone bitten by an infected tick will develop the disorder, and in some cases the bacteria may remain localized and not progress to later stages of development.

Differential Diagnosis (Other conditions with similar appearance)
Aseptic meningitis
Fibromyalgia
Reactive arthritis
Rheumatoid arthritis
Systemic Lupus erythematosus

Diagnosis
Key Points
Diagnosis based on appearance of the affected area, including the presence of Erythema migrans
Other tests including laboratory and skin biopsy may be performed to confirm diagnosis and to rule out other conditions

Lyme disease is typically diagnosed based on the characteristic appearance of Erythema migrans in the affected area. Other tests including skin biopsy and laboratory tests may be performed to confirm the diagnosis and rule out other, similar appearing conditions.

Treatment
Complete cures may be affected
Goal of treatment is the elimination of the causal agent and alleviation of symptoms
*Chances of successful cure decrease as the condition progresses without treatment

Successful treatment of Lyme disease is predicated on early diagnosis in most cases. Early stage and localized cases are typically treated with effectiveness with antibiotic medications, and a full cure may be affected. Health care professionals will determine the best antibiotic based on bacterial sensitivity tests. For cases in the late stage of development, intravenous administration of antibiotics is recommended.