Tick- and louse-borne relapsing fever: Difference between revisions

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* Infections caused by ''[[Borrelia]]'' spp.
*Infections caused by ''[[Borrelia]]'' spp.
**'''[[Tick-borne relapsing fever]]''' (TBRF) is caused by non-Lyme ''Borrelia'' species
**'''[[Louse-borne relapsing fever]]''' (LBRF) is caused by ''B. recurrentis''


{| class="wikitable"
== Microbiology ==
!Species

!Vector
* '''Tick-borne relapsing fever (TBRF)''' is caused by multiple non-Lyme ''Borrelia'' species with global distribution
!Distribution
* '''Louse-borne relapsing fever (LBRF)''' is caused by '''''B. recurrentis'''''
!Reservoir
* 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
|-
|-
! colspan="4" |Tick-borne relapsing fever (TBRF)
| TBRF
|
|
|
|-
|-
|  ''B. hermsii''
|''B. hermsii''
| ''Ornithodoros hermsii''
|''Ornithodoros hermsii''
| Western US and Canada (most common)
|Western US and Canada (most common)
| Rodent
|Rodent
|-
|-
|  ''B. turicatae''
|''B. turicatae''
| ''O. turicata''
|''Ornithodoros turicata''
| Southwestern US
|Southwestern US
| Rodent
|Rodent
|-
|-
| '' B. parkeri''
|''B. parkeri''
| ''O. parkeri''
|''Ornithodoros parkeri''
| Western US and Baja California
|Western US and Baja California
| Rodent
|Rodent
|-
|-
| '' B. mazzottii''
|''B. mazzottii''
| ''O. talaje''
|''Ornithodoros talaje''
| Mexico and Central America
|Mexico and Central America
| Rodent
|Rodent
|-
|-
| '' B. venezuelensis''
|''B. venezuelensis''
| ''O. rudis''
|''Ornithodoros rudis''
| South America
|South America
| Rodent
|Rodent
|-
|-
| '' B. crocidurae''
|''B. crocidurae''
| ''O. erraticus''
|''Ornithodoros erraticus''
| Middle East
|Middle East
| Rodent
|Rodent
|-
|-
| '' B. hispanica''
|''B. hispanica''
| ''O. marocanus''
|''Ornithodoros marocanus''
| Iberian peninsula and North Africa
|Iberian peninsula and North Africa
|
|
|-
|-
! colspan="4" |Louse-borne relapsing fever (LBRF)
| LBRF
|
|
|
|-
|-
|  ''B. recurrentis''
|''[[Borrelia recurrentis|B. recurrentis]]''
| ''Pediculus humanus''
|''Pediculus humanus''
| Ethiopia/Eastern Africa (previously worldwide)
|Ethiopia/Eastern Africa (previously worldwide)
|
|
|-
|-
| Other
! colspan="4" |Other
|
|
|
|-
|-
|  ''B. miyamotoi''
|''B. miyamotoi''
| ''Ixodes dammini'' and ''I. scapularis''
|''Ixodes dammini'' and ''I. scapularis''
| US, Russia, and Japan
|US, Russia, and Japan
| Deer
|Deer
|-
|-
|  ''B. lonestari''
|''B. lonestari''
| ''Amblyomma americanum''
|''Amblyomma americanum''
| Southern US
|Southern US
| Deer & lizards
|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


[[Category:Borrelioses]]
[[Category:Borrelioses]]

Latest revision as of 23:51, 30 July 2020

Species Vector Distribution Reservoir
Tick-borne relapsing fever (TBRF)
B. hermsii Ornithodoros hermsii Western US and Canada (most common) Rodent
B. turicatae Ornithodoros turicata Southwestern US Rodent
B. parkeri Ornithodoros parkeri Western US and Baja California Rodent
B. mazzottii Ornithodoros talaje Mexico and Central America Rodent
B. venezuelensis Ornithodoros rudis South America Rodent
B. crocidurae Ornithodoros erraticus Middle East Rodent
B. hispanica Ornithodoros marocanus Iberian peninsula and North Africa
Louse-borne relapsing fever (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
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