Borrelia recurrentis is a spirochete responsible for louse-borne relapsing fever, an epidemic disease historically associated with war, famine, and refugee settings.
Unlike Lyme disease (caused by B. burgdorferi), this species is transmitted via the human body louse and spreads rapidly in crowded, unhygienic environments.

🔬 Characteristics

Gram-negative, spiral-shaped spirochete with endoflagella giving a corkscrew motility.
Larger than treponemes (syphilis-causing spirochetes).
Exhibits antigenic variation – changes its surface proteins (variable major proteins, Vmps) → enables immune evasion and recurrent fever episodes. 🔄

🌍 Source & Transmission

Spread exclusively by the human body louse (Pediculus humanus humanus). 🪳
Transmission occurs when lice are crushed on the skin, releasing spirochetes into abrasions (not by bite itself).
Epidemics historically linked to war, poverty, and refugee camps (e.g. Ethiopia, East Africa).

⚠️ Pathogenicity (Clinical Features)

Relapsing fever: Sudden onset of high fever, rigors, chills, severe headache, myalgia, and delirium.
Organomegaly: Splenomegaly and hepatomegaly are common.
Respiratory features: cough and sometimes pneumonia-like illness.
Relapses: Episodes recur every 7–10 days due to antigenic variation, with each febrile episode lasting ~3–6 days before spontaneous remission.
Complications include jaundice, myocarditis, and CNS involvement in severe cases.

🧪 Investigations

Blood smear with Giemsa or Wright stain: Best during febrile episodes, when spirochetemia is highest.
Serology is unreliable due to antigenic variation.
PCR may help in confirmation but is not widely available in resource-limited endemic areas.

💊 Sensitivity

Highly sensitive to Tetracyclines (e.g. doxycycline) and erythromycin.

🩺 Management

First-line: Doxycycline 100 mg twice daily for 7–10 days.
Alternatives: Erythromycin (especially in pregnancy or children <8 yrs).
Jarisch–Herxheimer reaction: A common complication after antibiotic initiation due to rapid lysis of spirochetes → presents with rigors, hypotension, and worsening fever. Treat supportively with IV fluids, antipyretics, and monitoring.
Prevention: Louse control through improved hygiene, clothing washing, and insecticide treatment in refugee and outbreak settings.

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Borrelia recurrentis

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