Borrelia recurrentis

From IDWiki
Borrelia recurrentis
  • Causes Louse-borne relapsing fever (LBRF)

Background

Microbiology

  • Spirochete
  • Serotypes are determined by the outer membrane variable major proteins (vmp)
  • Grow in modified Kelly medium and stained by Wright stain (in peripheral blood film)

Epidemiology

  • Vector-borne disease transmitted by the human body louse (Pediculus humanus humanus)
  • LBRF was present nearly worldwide prior to World War II, but is now present in Ethiopia
  • Associated with homelessness and refugee camps

Pathophysiology

  • During febrile periods, spirochetes divide rapidly and cause a spirochetemia
  • This is followed by an immune response to the vmp proteins, which clears the spirochetemia and the patient becomes afebrile
  • The vmp proteins undergo rearrangement, evading the immune system and allowing another spirochetemia
    • This is the cause of the relapsing fever

Clinical Manifestations

  • Incubation period of 7 days (range 2 to 18 days)
  • Relapsing fevers: febrile for 3 days, afebrile for 7 days
  • Some patients will have lymphadenopathy, hepatosplenomegaly, and a rash
  • Rare complications include lymphocytic meningitis, Bell palsy and other cranial nerve palsies, paralysis, seizure, uveitis, endophthalmitis, ARDS, and myocarditis
  • Can cause spontaneous abortion in pregnant women
  • May be septic, with multiple organ involvement
  • May have a Jarisch-Herxheimer reaction following empiric antibiotics

Differential Diagnosis

Diagnosis

  • Often seen on blood film
    • Giemsa or Wright stains
    • 70% sensitive during febrile period for TBRF, lower for LBRF
  • Acute-convalescent serology with IFA/EIA
    • May cross-react with Lyme disease
  • Can cause a false-positive VDRL
  • Can be cultured with modified Kelly medium

Management

  • First-line: Doxycycline 200 mg po once
  • Alternatives:
    • Penicillin G 400-800 kU IM once
    • Erythromycin 500 mg po once

Prevention

  • Can do post-exposure prophylaxis with doxycycline 200 mg po once followed by 100 mg daily for 4 days