Dermatology - Lyme Disease

Dermatology - Lyme Disease
Lyme disease, which is caused by spirochetes called Borrelia, is the most prevalent vector-borne illness in the US, accounting for 30,000 cases annually. The disease is spread via tick bites.

Stage 1: Up to 30 days after a tick bite, a severe sickness with fever, chills, myalgia, headache, weakness, and photophobia might ensue. Stage 2: Symptoms that appear days to weeks after the bite include neurologic (meningitis, cranial neuritis, and peripheral neuritis), cardiac (AV nodal block), and musculoskeletal (myalgia, arthralgia). Stage 3: Weeks to months later, polyneuropathy, chronic arthralgia, and persistent arthritis develop.


Stage 1: An erythematous plaque, also known as erythema migrans, characterized by a red border and a fast centrifugal lesion expansion. The lesion may either produce multiple concentric rings of varied shades of red (targetoid look) or remain uniformly red as it grows.
Days to weeks after a tick bite, stage 2 happens. Similar lesions to erythema migrants are observed; however, they differ in size, travel less, lack central induration, and sometimes have scaly appearance.
Stage 3  happens when acrodermatitis chronica atrophicans first appears, it usually affects one extremity and is characterized by a diffuse or localized violaceous erythema, modest to substantial edema, and Lyme disease. Over months to years, the lesion spreads centrifugally, leaving behind visible veins, subcutaneous tissue, and central atrophy. Subcutaneous nodules around the knees and elbows are indicative of localized fibromas and plaques.

For Stage 1 disease, the diagnosis is made clinically; for Stages 2 and 3, the diagnosis is determined based on the presence of antibodies. Other insect bites, tinea, allergic contact dermatitis, pityriasis rosea, fixed drug eruption, erythema multiforme, and urticaria are among the differential diagnoses.

Doxycycline, 100 mg twice day, is the first-line treatment for all patients over 9 years old who are not pregnant. Give amoxicillin 50 mg/kg daily to children younger than nine years old.
For adults, amoxicillin 500 mg three times a day is the second-line treatment. Erythromycin 250 mg four times a day or cefuroxime axetil 500 mg twice a day are substitutes.
For Stage 1 disease, continue antibiotics for 14 days; for Stage 2 disease, continue for 21 days; and for Stage 3 disease, continue for 30–60 days. For any patients exhibiting cardiac or neurological symptoms, think about administering IV antibiotics.