Tick- and louse-borne relapsing fever: Difference between revisions
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* Infections caused by ''[[Borrelia]]'' spp. |
* Infections caused by ''[[Borrelia]]'' spp. |
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= Microbiology = |
== Microbiology == |
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* '''Tick-borne relapsing fever (TBRF)''' is caused by multiple non-Lyme ''Borrelia'' species with global distribution |
* '''Tick-borne relapsing fever (TBRF)''' is caused by multiple non-Lyme ''Borrelia'' species with global distribution |
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= Epidemiology = |
== Epidemiology == |
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* TBRF is transmitted by ''Ornithodoros'' species ticks, with rodent reservoirs |
* TBRF is transmitted by ''Ornithodoros'' species ticks, with rodent reservoirs |
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** Associated with homelessness and refugee camps |
** Associated with homelessness and refugee camps |
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= Pathophysiology = |
== Pathophysiology == |
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* During febrile periods, spirochetes divide rapidly and cause a spirochetemia |
* During febrile periods, spirochetes divide rapidly and cause a spirochetemia |
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** This is the cause of the relapsing fever |
** This is the cause of the relapsing fever |
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= Clinical Presentation = |
== Clinical Presentation == |
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* Incubation period of 7 days (range 2 to 18 days) |
* Incubation period of 7 days (range 2 to 18 days) |
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* May have a Jarisch-Herxheimer reaction following empiric antibiotics |
* May have a Jarisch-Herxheimer reaction following empiric antibiotics |
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= Differential Diagnosis = |
== Differential Diagnosis == |
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== Tick-borne relapsing fever == |
=== Tick-borne relapsing fever === |
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* Colorado tick fever (Coltivirus) |
* Colorado tick fever (Coltivirus) |
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* Lyme disease |
* Lyme disease |
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== Louse-borne relapsing fever == |
=== Louse-borne relapsing fever === |
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* Typhus |
* Typhus |
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* Dengue |
* Dengue |
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= Diagnosis = |
== Diagnosis == |
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* Often seen on blood film |
* Often seen on blood film |
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* Can be cultured with modified Kelly medium |
* Can be cultured with modified Kelly medium |
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= Management = |
== Management == |
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== Tick-borne relapsing fever == |
=== Tick-borne relapsing fever === |
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* First-line: Doxycycline 100 mg po bid for 7 to 10 days |
* First-line: Doxycycline 100 mg po bid for 7 to 10 days |
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** Ceftriaxone 2 g IV q24h for 10-14 days |
** Ceftriaxone 2 g IV q24h for 10-14 days |
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== Louse-borne relapsing fever == |
=== Louse-borne relapsing fever === |
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* First-line: Doxycycline 200 mg po once |
* First-line: Doxycycline 200 mg po once |
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** Erythromycin 500 mg po once |
** Erythromycin 500 mg po once |
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= Prevention = |
== Prevention == |
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* Can do post-exposure prophylaxis with doxycycline 200 mg po once followed by 100 mg daily for 4 days |
* Can do post-exposure prophylaxis with doxycycline 200 mg po once followed by 100 mg daily for 4 days |
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Revision as of 00:08, 16 August 2019
- Infections caused by Borrelia spp.
Microbiology
- Tick-borne relapsing fever (TBRF) is caused by multiple non-Lyme Borrelia species with global distribution
- Louse-borne relapsing fever (LBRF) is caused by B. recurrentis
- Other non-Lyme Borrelia species include B. miyamotoi and B. lonestari, although B. lonestari may also be able to cause TBRF
- Borrelia are spirochetes
- 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)
| Species | Vector | Distribution | Reservoir |
|---|---|---|---|
| TBRF | |||
| B. hermsii | Ornithodoros hermsii | Western US and Canada (most common) | Rodent |
| B. turicatae | O. turicata | Southwestern US | Rodent |
| B. parkeri | O. parkeri | Western US and Baja California | Rodent |
| B. mazzottii | O. talaje | Mexico and Central America | Rodent |
| B. venezuelensis | O. rudis | South America | Rodent |
| B. crocidurae | O. erraticus | Middle East | Rodent |
| B. hispanica | O. marocanus | Iberian peninsula and North Africa | |
| LBRF | |||
| B. recurrentis | Pediculus humanus | Ethiopia/Eastern Africa (previously worldwide) | |
| Other | |||
| B. miyamotoi | Ixodes dammini and I. scapularis | US, Russia, and Japan | Deer |
| B. lonestari | Amblyomma americanum | Southern US | Deer & lizards |
Epidemiology
- TBRF is transmitted by Ornithodoros species ticks, with rodent reservoirs
- Present on every continent except Australia and Antarctica
- In North America, it is mostly in the Rocky Mountain regions above 1500 feet elevation
- Most have exposure to woodpiles or cabins with rodents
- Spirochetes can survive in the tick for years, and can be transmitted vertically within ticks
- Doesn't need its mammalian host to complete its life cycle
- Ticks feed for short periods (20 min) and are painless, so is often not noticed
- Can be transmitted vertically, by transfusion, and from laboratory exposure
- 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 Presentation
- Incubation period of 7 days (range 2 to 18 days)
- Relapsing fevers: febrile for 3 days, afebrile for 7 days
- TBRF can relapse up to 30 times, whereas LBRF is usually self-limited after a single relapse
- Febrile periods may be associated with headache, myalgia, arthralgia, dizziness, and vomiting
- Each relapse is usually less severe
- 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
Tick-borne relapsing fever
- Colorado tick fever (Coltivirus)
- Brucellosis
- Tularemia
- Juvenile rheumatoid arthritis
- Leptospirosis
- Occult malignancy
- Lyme disease
Louse-borne relapsing fever
- Typhus
- Malaria
- Typhoid fever
- Leptospirosis
- Hepatitis
- Dengue
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
Tick-borne relapsing fever
- First-line: Doxycycline 100 mg po bid for 7 to 10 days
- Alternatives: erythromycin 500 mg qid for 10 days
- If CNS involvement:
- Penicillin G 3 mU IV q4h for 10-14 days, or
- Ceftriaxone 2 g IV q24h for 10-14 days
Louse-borne relapsing fever
- 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
