Borrelia recurrentis
From IDWiki
- 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
