Relapsing Fever in Emergency Medicine Clinical Presentation

Updated: Jun 08, 2016
  • Author: Bobak Zonnoor , MD; Chief Editor: Jeter (Jay) Pritchard Taylor, III, MD  more...
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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 is typically 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. [11] 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 also 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. [12]

Over the last several years, acute respiratory distress syndrome (ARDS) has been reported in several patients with relapsing fever in North America. [13]

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
  • Petechial, ecchymosis (more common in patients with louse-borne relapsing [14] )
  • Epistaxis (common in louse-borne disease)
  • Abnormal lung findings (rales, rhonchi)
  • Nuchal rigidity (more common in louse-borne relapsing): Neurological manifestations are believed to be secondary to spirochetemia rather than direct invasion of central nervous system.
  • Lymphadenopathy [15]
  • 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, neurological 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.