Tick-borne relapsing fever: Difference between revisions
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− | * |
+ | *'''Tick-borne relapsing fever''' (TBRF) is caused by a number of non-Lyme ''Borrelia'' species |
− | == |
+ | ==Background== |
− | === |
+ | ===Microbiology=== |
+ | |||
− | * Tick-borne relapsing fever is caused by multiple non-Lyme ''Borrelia'' species with global distribution, usually carried by [[Ornithodorus species]] ticks |
||
− | * |
+ | *Tick-borne relapsing fever is caused by multiple non-Lyme ''Borrelia'' species with global distribution, usually carried by [[Ornithodorus]] ticks |
+ | *Other non-Lyme ''Borrelia'' species include ''B. miyamotoi'' and ''B. lonestari'', although ''B. lonestari'' may also be able to cause TBRF |
||
− | * ''Borrelia'' are spirochetes |
||
+ | *''Borrelia'' are [[Shape::spirochete|spirochetes]] |
||
− | * Serotypes are determined by the outer membrane variable major proteins (vmp) |
||
+ | *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) |
||
+ | *Grow in modified Kelly medium and stained by Wright stain (in peripheral blood film) |
||
{| class="wikitable" |
{| class="wikitable" |
||
− | ! |
+ | !Species!!Vector!!Distribution!!Reservoir |
|- |
|- |
||
− | | |
+ | |''[[Borrelia hermsii|B. hermsii]]''||''O. hermsii''||Western US and Canada (most common)||squirrels and chipmucks |
|- |
|- |
||
− | | |
+ | |''[[Borrelia turicatae|B. turicatae]]''||''O. turicata''||Southwestern US||Rodent |
|- |
|- |
||
− | | |
+ | |''[[Borrelia parkeri|B. parkeri]]''||''O. parkeri''||Western US and Baja California||Rodent |
|- |
|- |
||
− | | |
+ | |''[[Borrelia mazzottii|B. mazzottii]]''||''O. talaje''||Mexico and Central America||Rodent |
|- |
|- |
||
− | | |
+ | |''[[Borrelia venezuelensis|B. venezuelensis]]''||''O. rudis''||South America||Rodent |
|- |
|- |
||
− | | |
+ | |''[[Borrelia crocidurae|B. crocidurae]]''||''O. erraticus''||Middle East||Rodent |
|- |
|- |
||
− | | |
+ | |''[[Borrelia hispanica|B. hispanica]]''||''O. marocanus''||Iberian peninsula and North Africa|| |
|} |
|} |
||
− | === |
+ | ===Epidemiology=== |
+ | |||
− | * TBRF is transmitted by [[Ornithodoros species]] ticks, with rodent reservoirs |
||
+ | *TBRF is transmitted by [[Vector::Ornithodoros]] ticks, with rodent reservoirs |
||
− | * Present on every continent except Australia and Antarctica |
||
+ | *Present on every continent except Australia and Antarctica |
||
− | * In North America, it is mostly in the Rocky Mountain regions above 1500 feet elevation |
||
+ | *In North America, it is mostly in the Rocky Mountain regions above 1500 feet elevation |
||
− | ** Most have exposure to woodpiles or cabins with rodents |
||
+ | **Most have exposure to woodpiles or cabins with rodents |
||
− | * Spirochetes can survive in the tick for years, and can be transmitted vertically within ticks |
||
+ | *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 |
||
+ | **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 |
||
+ | *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 |
||
+ | *Can be transmitted vertically, by transfusion, and from laboratory exposure |
||
+ | |||
+ | ===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 [[Usual incubation period::7 days]] (range [[Incubation period range::2 to 18 days]]) |
||
+ | *[[Causes::Relapsing fever]]: febrile for 3 days (range 12 hours to 17 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 [[Causes::headache]], [[Causes::myalgias]], [[Causes::chills]], [[Causes::arthralgias]], [[Causes::dizziness]], and [[Causes::vomiting]] |
||
+ | **Sometimes [[Causes::abdominal pain]], [[Causes::confusion]], [[Causes::non-productive cough]], [[Causes::eye pain]], [[Causes::diarrhea]], [[Causes::photophobia]], and [[Causes::neck pain]] |
||
+ | **Each relapse is usually less severe |
||
+ | **A minority of patients will have lymphadenopathy, hepatosplenomegaly, a rash, dysuria, jaundice |
||
+ | *Rare complications include lymphocytic meningitis, Bell palsy and other cranial nerve palsies, paralysis, seizure, uveitis, endophthalmitis, ARDS, and myocarditis |
||
+ | *[[Causes::Thrombocytopenia]] on bloodwork |
||
+ | *May be septic, with multiple organ involvement |
||
+ | *Can cause spontaneous abortion in pregnant women |
||
+ | *May have a [[Causes::Jarisch-Herxheimer]] reaction following antibiotics |
||
+ | |||
+ | ==Differential Diagnosis== |
||
+ | |||
+ | *[[Colorado tick fever]] (Coltivirus) |
||
+ | *[[Brucellosis]] |
||
+ | *[[Tularemia]] |
||
+ | *Juvenile rheumatoid arthritis |
||
+ | *[[Leptospirosis]] |
||
+ | *Occult malignancy |
||
+ | *[[Lyme disease]] |
||
+ | ==Diagnosis== |
||
− | === 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 |
||
+ | *Often seen on blood film |
||
− | == Clinical Presentation == |
||
+ | **Giemsa or Wright stains |
||
− | * Incubation period of 7 days (range 2 to 18 days) |
||
− | * |
+ | **70% sensitive during febrile period for TBRF, lower for LBRF |
+ | *Acute-convalescent serology with IFA/EIA |
||
− | * TBRF can relapse up to 30 times, whereas LBRF is usually self-limited after a single relapse |
||
+ | **May cross-react with Lyme disease |
||
− | ** Febrile periods may be associated with headache, myalgia, arthralgia, dizziness, and vomiting |
||
+ | *Can cause a false-positive VDRL |
||
− | ** Each relapse is usually less severe |
||
+ | *Can be cultured with modified Kelly medium |
||
− | * 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 |
||
+ | ==Management== |
||
− | == Differential Diagnosis == |
||
− | * [[Colorado tick fever]] (Coltivirus) |
||
− | * [[Brucellosis]] |
||
− | * [[Tularemia]] |
||
− | * Juvenile rheumatoid arthritis |
||
− | * [[Leptospirosis]] |
||
− | * Occult malignancy |
||
− | * [[Lyme disease]] |
||
+ | *First-line: [[Is treated by::doxycycline]] 100 mg po bid for 7 to 10 days |
||
− | == Diagnosis == |
||
+ | *Alternatives: [[Is treated by::erythromycin]] 500 mg qid for 10 days |
||
− | * Often seen on blood film |
||
+ | *If CNS involvement: |
||
− | ** Giemsa or Wright stains |
||
+ | **[[Is treated by::Penicillin]] G 3 mU IV q4h for 10-14 days, or |
||
− | ** 70% sensitive during febrile period for TBRF, lower for LBRF |
||
+ | **[[Is treated by::Ceftriaxone]] 2 g IV q24h for 10-14 days |
||
− | * 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 |
||
− | == |
+ | ==Prevention== |
− | === Tick-borne relapsing fever === |
||
− | * First-line: [[Is treated by::doxycycline]] 100 mg po bid for 7 to 10 days |
||
− | * Alternatives: [[Is treated by::erythromycin]] 500 mg qid for 10 days |
||
− | * If CNS involvement: |
||
− | ** [[Is treated by::Penicillin]] G 3 mU IV q4h for 10-14 days, or |
||
− | ** [[Is treated by::Ceftriaxone]] 2 g IV q24h for 10-14 days |
||
+ | *Can do post-exposure prophylaxis with [[doxycycline]] 200 mg po once followed by 100 mg daily for 4 days |
||
− | == 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 22:52, 7 February 2022
- Tick-borne relapsing fever (TBRF) is caused by a number of non-Lyme Borrelia species
Background
Microbiology
- Tick-borne relapsing fever is caused by multiple non-Lyme Borrelia species with global distribution, usually carried by Ornithodorus ticks
- 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 |
---|---|---|---|
B. hermsii | O. hermsii | Western US and Canada (most common) | squirrels and chipmucks |
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 |
Epidemiology
- TBRF is transmitted by Ornithodoros 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
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 fever: febrile for 3 days (range 12 hours to 17 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, myalgias, chills, arthralgias, dizziness, and vomiting
- Sometimes abdominal pain, confusion, non-productive cough, eye pain, diarrhea, photophobia, and neck pain
- Each relapse is usually less severe
- A minority of patients will have lymphadenopathy, hepatosplenomegaly, a rash, dysuria, jaundice
- Rare complications include lymphocytic meningitis, Bell palsy and other cranial nerve palsies, paralysis, seizure, uveitis, endophthalmitis, ARDS, and myocarditis
- Thrombocytopenia on bloodwork
- May be septic, with multiple organ involvement
- Can cause spontaneous abortion in pregnant women
- May have a Jarisch-Herxheimer reaction following antibiotics
Differential Diagnosis
- Colorado tick fever (Coltivirus)
- Brucellosis
- Tularemia
- Juvenile rheumatoid arthritis
- Leptospirosis
- Occult malignancy
- Lyme disease
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 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
Prevention
- Can do post-exposure prophylaxis with doxycycline 200 mg po once followed by 100 mg daily for 4 days