Relapsing Fever in Emergency Medicine Clinical Presentation

Updated: Feb 15, 2023
  • Author: Bobak Zonnoor , MD, MMM; Chief Editor: Jeter (Jay) Pritchard Taylor, III, MD  more...
  • Print


Relapsing fever develops abruptly, 3-18 days (average, 7-8 days) after exposure to the spirochete. The incubation period is approximately 7 days.

As with all the tick-borne diseases, the season of onset and epidemiologic history suggesting possible tick exposure are important clues. Ornithodoros ticks often frequent caves and decaying woodpiles. Many patients report a history of having spent time in rustic cabins in which the ticks gain access by hitching a ride on a rodent.

High fever is typical.

Onset of symptoms generally is abrupt.

Two or more episodes of high fever occur, usually higher than 39°C.

Symptoms can recur, producing a telltale pattern of fever lasting roughly 3 days, followed by 7 days without fever, followed by another 3 days of fever. Without antibiotic treatment, this can repeat several times. In louse-borne relapsing fever, the first febrile episode is usually unremitting, lasting 3-6 days, and it typically is followed by a single milder episode. In tick-borne relapsing fever, multiple febrile periods last 1-3 days each. In both forms, the interval between febrile episodes ranges from 4-14 days.

The first fever episode usually ends with “crisis,” such as rigors, and is associated with labile blood pressures and pulse, lasting 15-30 minutes, followed by profuse diaphoresis, falling temperatures, and hypotension, typically over a few hours. [12] Louse-borne relapsing fever normally produces fewer relapses (usually one relapse). Tick-borne relapsing fever produces an average of 3 relapses; however, in some cases more than 10 relapses occur.

Other symptoms are nonspecific. Headache is a very common symptom, occurring in nearly 95% of cases. Patients also complain of nausea, vomiting, and upper abdominal pain (due to liver and spleen involvement) during febrile episodes.

Myalgia and chills occur in approximately 90% of cases.

The following are other potential symptoms:

  • Arthralgia
  • Joint aches
  • Weakness
  • Anorexia
  • Weight loss
  • Non-productive cough (more common in louse-borne relapsing fever)

Localizing neurologic symptoms (eg, flaccid paralysis, myelitis, radiculopathy, hemiplegia) are more common in tick-borne relapsing. There has been a case report of meningoencephalitis. Delirium can be seen in both tick-borne relapsing and louse-borne relapsing. [13]

Over the last several years, acute respiratory distress syndrome (ARDS) has been reported in several patients with relapsing fever in North America. [14]

Hepatic and splenic involvement are more common in louse-borne relapsing fever.



Physical findings are not diagnostic but may include the following:

  • Fever (most common finding)
  • Abdominal tenderness with hepatosplenomegaly
  • Petechiae, ecchymosis (more common in patients with louse-borne relapsing [15] )
  • Epistaxis (common in louse-borne disease)
  • Abnormal lung findings (rales, rhonchi)
  • Nuchal rigidity (more common in louse-borne relapsing): Neurologic manifestations are believed to be secondary to spirochetemia rather than direct invasion of central nervous system.
  • Lymphadenopathy [16]
  • Jaundice
  • Iritis and iridocyclitis
  • Gallop reflecting heart disease/myocarditis: Myocarditis appears to be common in both louse-borne relapsing and tick-borne relapsing and has been prominent in fatal cases.
  • Neurologic findings are more common in tick-borne disease and include coma, cranial neuropathy (especially Bell palsy), hemiplegia, meningitis, and seizures. In louse-borne relapsing, neurologic findings include nuchal rigidity, mental status changes, and neck stiffness.
  • Rash is more common in tick-borne relapsing.


Relapsing fever is caused by infection with the causative Borrelia species.



Bleeding is a common complication with both forms of relapsing fever. Bleeding in the skin, nose, eyes, lungs, urinary tract, GI tract, and brain can occur. The latter two can be fatal.

Jarisch Herxheimer reaction (JHR) may occur.

Acute respiratory distress syndrome (ARDS) may occur.

In pregnant women, premature labor, spontaneous abortion, and transplacental spread with neonatal death have been reported.