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Tick-Borne Relapsing Fever
Aka: Tick-Borne Relapsing Fever, Relapsing Fever
- See Also
- Tick-Borne Illness
- Borrelia
- Epidemiology
- Rare: <500 cases reported in U.S. in last 25 years
- Region
- U.S. West of the Mississippi River
- More common in mountains
- Pathophysiology
- Cause
- Spirochete in Borrelia genus
- Vectors
- Soft Ticks (Ornithodoros genus)
- Other Borrelia species cause Relapsing Fever in Africa and Russia
- Borrelia hermsii (reservoir: Squirrels and chipmunks)
- Borrelia tunicate (reservoir: Cattle, rodents, pigs)
- Borrelia miyamotoi
- Body Lice (human to human transmission)
- Borrelia recurrentis
- Exposure
- Mountain cabin with rodents
- Cave exploration
- Work under buidlings
- Relapsing Fever
- Infections often involve multiple Borrelia serotypes
- As one serotype is cleared, another proliferates
- May lie dormant in liver, Spleen, CNS, marrow
- Alternating serotypes, dormancy cause Relapsing Fever
- Symptoms (follows 7 day incubation period)
- Fever
- Sudden onset, over 102.5 F (39.2 C)
- May rise over 104 F
- Pattern
- Fever for 3 to 6 days
- Febrile period ends with 30 minute crisis period
- Brief spike in pulse and Blood Pressure
- Sweats occur as the fever abates
- Fever recurs every 4 to 14 days
- Associated symptoms
- Headache
- Myalgias and Arthralgias
- Chills
- Nausea or Vomiting
- Abdominal Pain
- Signs
- Hepatomegaly (10%)
- Splenomegaly (6%)
- Meningitis (2%)
- Pneumonitis
- Myocarditis
- Iridiocyclitis
- Cranial Nerve palsy (e.g. Bell's Palsy, Deafness)
- Altered Level of Consciousness (Delirium, coma)
- Labs: Diagnosis
- Microscopic exam of blood, CSF other body fluid
- Thick and thin smears stained with Wright's or Giemsa
- Spirochetes identified
- Blood Cultures during febrile period
- Immunofluorescence and PCR not widely available
- Labs: Other findings
- Complete Blood Count
- Anemia
- Slight Leukocytosis
- Thrombocytopenia
- Liver Function Tests
- Increased Unconjugated Bilirubin
- Increased Aminotransferases
- Urinalysis
- Proteinuria and Hematuria
- Labs: If indicated
- Myocarditis suspected
- EKG with Prolonged QT interval (QTc)
- Meningitis suspected
- CSF mononuclear Pleocytosis and increased CSF Protein
- Management
- Tick-Borne Infection
- Doxycycline 100 mg oral or IV twice daily for 7-10 days (preferred) OR
- Erythromycin 500 mg orally qid for 7-10 days
- Louse-borne Infection
- Tetracycline 500 mg oral or IV once OR
- Erythromycin 500 mg oral or IV once
- Complications
- Jarisch-Herxheimer Reaction (54% of treated cases)
- Occurs with treatment
- Onset within 2 hours of starting treatment
- Observe for 12 to 24 hours after starting treatment
- Acute Respiratory Distress Syndrome (ARDS)
- Encephalopathy
- Prognosis
- Mortality <1% in treated cases
- Poor prognostic factors
- Myocarditis
- Altered Level of Consciousness
- Poor liver function
- Bleeding complications from multiple sites
- Prevention
- See Prevention of Tick-borne Infection
- Spray susceptible buildings with Malathion 0.5%
- Keep home free of rodents
- References
- Dworkin (2002) Med Clin North Am 86:417-33 [PubMed]
- Roscoe (2005) Am Fam Physician 72(10):2039-44 [PubMed]