Tick-borne relapsing fever — DTM&H MCQ

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ModerateTropical Bacterial InfectionsTick-borne relapsing feverDTM&H

A 45-year-old farmer in China presents with relapsing fever with 3-day cycles, hepatosplenomegaly, and a blood film showing spirochaetes. He recalls a tick bite 2 weeks ago. What is the most likely organism?

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Correct answer: A — Borrelia duttoni

Tick-borne relapsing fever with spirochaetes on blood film in a person with tick exposure is caused by Borrelia duttoni (or other tick-borne Borrelia species transmitted by Ornithodoros soft ticks). B. recurrentis causes louse-borne relapsing fever. Relapsing episodes occur due to antigenic variation of the variable membrane proteins. Treatment: doxycycline or erythromycin, with caution for Jarisch-Herxheimer reaction. B. burgdorferi causes Lyme disease, not relapsing fever.

Reference: Manson's Tropical Diseases; CDC