Tickborne Relapsing Fever


Borrelia hermsii, B. turicatae

Where Found

TBRF occurs most commonly in 14 western states: Arizona, California, Colorado, Idaho, Kansas, Montana, Nevada, New Mexico, Oklahoma, Oregon, Texas, Utah, Washington, and Wyoming. Most cases occur in the summer when people vacation and sleep in rustic cabins. However, TBRF can also occur in the winter months when fires started to warm a cabin activate ticks resting in the walls and woodwork. In Texas, TBRF may be associated with cave exposure.

Incubation Period

~7 days, followed by recurring febrile episodes that last ~3 days and are separated by afebrile periods of ~7 days.

Signs and Symptoms

  • Headache
  • Myalgia
  • Chills
  • Nausea, vomiting
  • Arthralgia
  • Facial palsy (rarely)

Common Findings on Routine Laboratory Tests

  • Normal to increased white blood cell count with a left shift
  • Mildly increased serum bilirubin
  • Mild to moderate thrombocytopenia
  • Elevated erythrocyte sedimentation rate
  • Slightly prolonged prothrombin time (PT) and partial thromboplastin time (PTT)

Laboratory Diagnosis

  • Organisms are best detected in blood (by microscopy or culture) obtained while a person is febrile.
  • Observation of Borrelia spirochetes in smears of peripheral blood
  • Serologic testing is appropriate for convalescent samples drawn 10–14 days post-illness onset.


Tickborne Relapsing Fever treatment regimen
Age Category Drug Dosage Maximum Duration, Days
Adults Tetracycline 500 mg four times per day, orally N/A 10
Erythromycin 500 mg four times per day, orally N/A 10
Ceftriaxone* 2 g per day, IV N/A 10-14
Children weighing <100 lbs. (45.4 kg) Erythromycin 12.5 mg/kg four times per day, orally 2g/day 10

*For CNS involvement

NOTE: When initiating antibiotic therapy, all patients should be observed during the first 2–4 hours of treatment for a Jarisch-Herxheimer reaction.

NOTE: Acute respiratory distress syndrome requiring intubation has occurred in several patients undergoing TBRF treatment.


Centers for Disease Control and Prevention. Acute respiratory distress syndrome in persons with tickborne relapsing fever—Three states, 2004–2005. MMWR Morb Mortal Wkly Rep 2007;56(41): 1073–1076.

Centers for Disease Control and Prevention. Tickborne relapsing fever—United States, 1990–2011. MMWR Morb Mortal Wkly Rep 2015 Jan 30;64(3):58-60.

Christensen AM, Pietralczyk E, Lopez JE, et al. Diagnosis and management of Borrelia turicatae infection in febrile soldier, Texas, USA. Emerg Infect Dis 2017 May;23(5):883-884.

Dworkin MS, Anderson DE Jr, Schwan TG, et al. Tick-borne relapsing fever in the northwestern United States and southwestern Canada. Clin Infect Dis 1998 Jan;26(1):122-31.

Hayes E B and Dennis DT. Relapsing fever. In: Kasper DL, Fauci AS, Longo DL, Braunwald E, Hauser SL, Jameson JL, eds. Harrison’s Principles of Internal Medicine. 16th ed. New York, NY: McGraw-Hill; 2004:991–995.

Rawlings JA. An overview of tick-borne relapsing fever with emphasis on outbreaks in Texas. Tex Med 1995.