Relapsing Fever in Emergency Medicine Treatment & Management

Updated: Aug 24, 2018
  • Author: Bobak Zonnoor , MD, MMM; Chief Editor: Jeter (Jay) Pritchard Taylor, III, MD  more...
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Approach Considerations

The antibiotics of choice in the treatment of relapsing fever penicillin and tetracyclines. There has been no evidence of acquired resistance to antibiotics.

The effectiveness of therapy can be assessed via serial testing of blood smears and observing the clearance of spirochetes from the blood. Most patients have undetectable spirochetes within 8 hours of the first dose of antibiotic. [11]


Emergency Department Care

Emergency department care of patients with relapsing fever focuses on establishing the diagnosis and excluding other treatable infections with which it can be confused. As mentioned in Workup, thin and thick smears are usually the first tests performed for suspected relapsing fever.

Louse-borne relapsing fever

Louse-borne relapsing fever is treated with the following:

  • Tetracycline 500 mg PO as a single dose (12.5 mg/kg in children)
  • Doxycycline 200 mg PO as a single dose (5 mg/kg in children)
  • Intramuscular penicillin G procaine (400,000-800,000 units) as a single dose
  • If tetracyclines are contraindicated, erythromycin 500 mg as a single dose (12.5 mg/kg in children) [19]

The recurrence rate in patients receiving the above-mentioned therapy is less than 5%.

If the patient cannot tolerate oral administration, intravenous doxycycline 250 mg or 500 mg can be used.

Tetracycline is contraindicated in pregnant and nursing women and children younger than 9 years.

Tick-borne relapsing fever

Tick-borne relapsing fever is more sporadic than louse-borne relapsing fever.

The relapse rate of tick-borne relapsing fever after single dose of antibiotic is about 20% higher, which might result from probable invasion of the brain by spirochetes. Protected by the blood-brain barrier, spirochetes can reinvade the blood once antibiotic levels have fallen.

Treatment of tick-borne relapsing fever is the same as louse-borne relapsing fever, except the treatment duration is 7-10 days because the relapse rate is 20% after single-dose treatment.

Antibiotic choices for tick-borne relapsing fever include the following:

  • Tetracycline 500 mg PO every 6 hours for 7-10 days
  • Doxycycline 100 mg PO twice daily for 7-10 days
  • If tetracyclines are contraindicated, erythromycin 500 mg PO every 6 hours for 7-10 days
  • If CNS involvement is suspected, a beta-lactam antibiotic should be given intravenously: penicillin G (3 million units q4h for 7-10 days) or ceftriaxone 2 g IV once daily for 10-14 days or 1 g IV twice daily (for 10-14 days)

The efficacy of treatment can be measured by clearance of spirochetes in the blood, which usually occurs approximately 8 hours after antibiotic administration. [11]

For patients in endemic regions, postexposure treatment with doxycycline can be used.



Consultation with an infectious diseases specialist may be appropriate.



No vaccine is available for either louse-borne relapsing fever or tick-borne relapsing fever. Thus, decreasing exposure is the major mean of preventing relapsing fever.

Avoid sleeping in rodent-infested buildings (rodent nests may not be visible).

Use insect repellent containing DEET or permethrin to prevent tick bites.

For patients in endemic regions, postexposure treatment with doxycycline can be used.

In 2006, Hasin et al published a study on postexposure prophylaxis with a 5-day course of doxycycline to prevent tick-borne relapsing fever. A 200-mg dose (day 1) followed by 100 mg daily for 4 more days had 100% efficacy (although the 95% confidence intervals were wide [46-100] because of small numbers of patients). [20]

In many situations (eg, a refugee camp), maintenance of personal hygiene is difficult or impossible.

Chemical delousing may be required in epidemic situations.

For louse-borne relapsing fever, maintaining personal hygiene to avoid lice prevents the disease.

See Tick-borne Diseases, Introduction.


Further Inpatient Care

Many patients with louse-borne relapsing fever are malnourished and will require inpatient care to correct their hypovolemia, coagulation abnormalities, and nutritional status.

Patients with abnormal mental status also require close observation with airway protection, as indicated.

Those with prolonged QTc intervals are best monitored with telemetry.

Be especially vigilant in monitoring for a JH reaction.


Further Outpatient Care

Refer patients to follow up with their primary care physician to address complete recovery, any malnutrition issues, and any laboratory or ECG abnormalities.