Early Lyme disease is transmitted by the Ixodes scapularis tick and is endemic to the northeastern United States. It commonly presents as erythema migrans rash but can also cause systemic symptoms like fatigue and joint pain or affect the nervous system, heart, and lymph nodes. Diagnosis is usually clinical based on rash appearance but serology testing is used for neurological or cardiac involvement. Treatment involves oral antibiotics for mild skin disease or intravenous antibiotics for more serious neurological or cardiac complications.

1. Early Lyme disease
Epidemiology
• Endemic to northeastern United States
• Ixodes scapularis tick transmits Borrelia burgdorferi
Manifestations
• Erythema migrans (80%)
• Systemic symptoms: malaise, fatigue, arthralgia
• Regional lymphadenopathy
• Neurologic: meningitis, CN palsy, radiculoneuritis
• Carditis: atrioventricular block
Diagnosis
• Clinical (if erythema migrans)
• B burgdorferi serology (if neurologic/cardiac disease)
Treatment
• Oral antibiotics (eg, doxycycline) – skin/mild disease
• IV antibiotics (eg, ceftriaxone) – neurologic/cardiac
disease