Erythema Chronicum Migrans

Characteristic clinical feature of Lyme borreliosis occurring in approximately 90% patients infected with Borrelia burgdorferi transmitted to humans by the bite of ticks from the genus Ixodes.

Lyme disease occurs in temperate regions of North America, Europe, and Asia. In some countries of Europe, the incidence of Lyme disease has been estimated to be over 100 per 100,000 people a year.

The characteristic manifestation of early Lyme disease (stage 1) is erythema migrans: a circular rash at the site of the infectious tick attachment that radiates from the bite, within 2 - 40 days. It expands over a period of days to weeks in 80-90% of people with Lyme disease. Pyrexia, arthritis, musculoskeletal symptoms and local lymphadenopathy may occur.

• Starts as a red macule or papule at the site of the tick bite after a 7-10 day delay.
• Expands over days to weeks and central clearing may or may not occur.
• Associated with other symptoms of infection including fatigue, myalgia, arthralgia, headache, fever, chills, stiff neck, regional lymphadenopathy.
• Also associated with carditis, neurological disease, arthritis, acrodermatitis chronica atrophicans (swollen, bluish-red skin lesion on a distal extremity).

• Local tick bite reactions
• Tinea
• Insect bites
• Cellulitis
• Plant dermatitis.

Culture and serology if necessary for diagnosis.

Although the rash will resolve spontaneously, antibiotics hasten resolution and help prevent progression to lyme disease:

• Doxycycline is the antibacterial of choice for early Lyme disease¹
• Amoxicillin, cefuroxime or azithromycin are alternatives if doxycycline is contra-indicated
• Intravenous cefotaxime, ceftriaxone, or benzylpenicillin is recommended for Lyme disease associated with moderate to severe cardiac or neurological abnormalities, late Lyme disease, and Lyme arthritis
• The duration of treatment is generally 2-4 weeks; Lyme arthritis requires longer treatment with oral antibacterial drugs

Avoid exposure to tick bites.