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.
• Starts as a red macule or papule at the site of the tick bite after a 7-10 day delay.
• It expands over a period of days to weeks in 80-90% of people with Lyme disease. 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
• Dermatitis

• Culture and serology may be 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 disease.¹
• Amoxicillin, cefuroxime or azithromycin are alternatives if doxycycline is contra-indicated.
• The duration of treatment recommended is 2-4 weeks.

• Avoid exposure to tick bites.