Tick- and louse-borne relapsing fever: Difference between revisions
From IDWiki
(→) |
No edit summary |
||
| Line 1: | Line 1: | ||
* Infections caused by ''[[Borrelia]]'' spp. |
* Infections caused by ''[[Borrelia]]'' spp. |
||
** '''Tick-borne relapsing fever''' (TBRF) is caused by non-Lyme ''Borrelia'' species |
** '''[[Tick-borne relapsing fever]]''' (TBRF) is caused by non-Lyme ''Borrelia'' species |
||
** '''Louse-borne relapsing fever''' (LBRF) is caused by ''B. recurrentis'' |
** '''[[Louse-borne relapsing fever]]''' (LBRF) is caused by ''B. recurrentis'' |
||
== Microbiology == |
|||
* Tick-borne relapsing fever is caused by multiple non-Lyme ''Borrelia'' species with global distribution |
|||
* Louse-borne relapsing fever 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) |
|||
{| class="wikitable" |
{| class="wikitable" |
||
| Line 74: | Line 65: | ||
| 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]] |
||
Revision as of 10:40, 16 August 2019
- 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
| 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 |
