AUTHOR AND EDITOR INFORMATION

Section 1 of 10  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• References

INTRODUCTION

Section 2 of 10  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• References

Background

Relapsing fever is characterized by recurrent acute episodes of fever followed by nonfebrile periods of increasing duration.

Relapsing fever is a disease that is spread by 2 distinct vector families, namely the human body louse (Pediculus humanus) and soft-bodied ticks (Ornithodoros), and is caused by various species of Borrelia. The human body louse spreads Borrelia recurrentis infection. Tick-borne relapsing fever can be caused by a least 15 different Borrelia species. Louse-borne relapsing fever is caused by Borrelia recurrentis. Borrelia turicatae, Borrelia hermsii, Borrelia parkeri, and Borrelia duttonii may cause the tick-borne relapsing fever.

Louse-borne and tick-borne relapsing fevers differ in their epidemiology and must be considered separately. The human body louse transmits an epidemic form and is always associated with B recurrentis, whereas a soft-bodied tick transmits the endemic relapsing fever and may be caused by several different Borrelia species. Borreliae are spirochetes that measure 5-20 µm long by 0.5 µm in diameter. Humans are the only host for louse-borne relapsing fever, whereas small mammals and lizards may serve as the natural reservoir for tick-borne Borrelia species.

Pathophysiology

After exposure from an infected louse or tick, spirochetes enter the skin and gain access to the blood stream. Then, the organism can be found in the spleen, liver, lungs, kidneys, central nervous system, and bone marrow.

In louse-borne relapsing fever, B recurrentis is found almost exclusively in the blood and lymph nodes. Louse-borne spirochetes are transmitted either by the bite of a louse or by inoculation of louse feces. Humans acquire infection when infected body lice are crushed and their fluids contaminate mucous membranes, bite wounds, or other breaks in the skin.

Frequency

United States

Tick-borne relapsing fever is endemic in the western states (ie, states west of the Mississippi River), especially sporadically in mountainous areas or in small familial clusters. Tick-borne relapsing fever caused by B hermsii infections occurs during the spring and summer months.

International

Louse-borne relapsing fever has disappeared in large regions of the world and is an important disease only in northeastern Africa (especially in the highlands of Ethiopia) and in South America.

Mortality/Morbidity

Neurological symptoms have been reported in up to 30% of the patients with relapsing fever and may include coma, meningitis, focal neurologic deficits, and seizures.

• Tick-borne relapsing fever is a serious disease; however, if treated, it has a mortality rate of less than 5%. If acquired during pregnancy, tick-borne relapsing fever poses a high risk of fetal loss (ie, up to 50%).
• The epidemic relapsing fever caused by the louse-borne species, B recurrentis, plagued Asia and Europe during the last century and resulted in an untreated patient mortality rate of up to 40%. People who are native to the endemic areas usually experience a milder form of the disease compared to visitors.
• Antibiotic treatment commonly causes a Jarisch-Herxheimer reaction (JHR) with rigors, fever, and hypotension. It is more severe with the louse-born form treated with penicillin. Pretreatment with steroids does not seem to alter this reaction.

CLINICAL

Section 3 of 10  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• References

History

The clinical hallmark of both forms of relapsing fever is 2 or more episodes of high fever, headaches, and myalgia. The mean incubation time is approximately 7 days. The clinical manifestations of the illness are similar for both forms of the infection.

• The onset of illness is sudden and consists of the following:
• • Fever (often >40°C)
  • Severe headache
  • Shaking chills
  • Sweats
  • Myalgias
  • Arthralgia without evidence of arthritis
  • Dizziness
  • Nausea and vomiting

Physical

• Conjunctivae injected
• Sclera icterus
• Dry mucous membrane
• Scattered petechiae on the trunk and extremities
• Photophobia
• Nonproductive cough
• Pleurisy pain
• Epistaxis and blood tinged sputum

DIFFERENTIALS

Section 4 of 10  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• References

Other Problems to be Considered

Colorado tick fever
Rite bite fever
Viral hepatitis

WORKUP

Section 5 of 10  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• References

Lab Studies

• Direct observation of spirochetes in peripheral blood smears, bone marrow aspirates, or cerebrospinal fluid confirms the diagnosis of relapsing fever. The organism is rarely found when patients are afebrile. The organism can be grown in culture.
• Smear results from 70% or more of patients with louse-borne relapsing fever are positive. Fewer smear results are positive for patients with tick-borne relapsing fever than for patients with louse-borne relapsing fever.
• Nonspecific laboratory findings include normal to mildly increased leukocyte counts and thrombocytopenia.

Other Tests

• Use dark-field or phase-contrast microscopy.
• Serum antibodies to Borrelia species can be detected by enzyme immunoassays. Care in interpreting these tests is required because false-positive tests for syphilis and Lyme disease have been described.

Staging

The smear of patients who are in the interval between relapses will not demonstrate the organism. The examination should be repeated when the fever reappears.

TREATMENT

Section 6 of 10  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• References

Medical Care

Relapsing fever from Borrelia species is very sensitive to antibiotics.

• In louse-borne relapsing fever, the treatment consists of a single dose of erythromycin, doxycycline, chloramphenicol, or penicillin G. Doxycycline is the preferred drug, except in children and pregnant women, where erythromycin or penicillin is preferred.
• Treatment of tick-borne relapsing fever is the same as with louse-borne fever, except the treatment course is approximately 7 days.
• One should expect that antibiotic treatment would precipitate a JHR. This reaction consists of fever, chills, and hypotension and usually occurs within the first 2 hours of initiating antibiotics.

MEDICATION

Section 7 of 10  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• References

The goals of pharmacotherapy are to reduce morbidity and to prevent complications.

Drug Category: Antibiotics

Relapsing fever from Borrelia species are sensitive to antibiotic agents.

FOLLOW-UP

Section 8 of 10  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• References

Deterrence/Prevention

• Louse-borne relapsing fever can be prevented by the elimination of circumstances that promote louse infection (eg, crowding, homelessness) and the initiation of personal hygiene practices that reduce body lice (eg, changing clothes at frequent intervals, bathing, washing clothes).
• Avoiding rodents can prevent tick-borne relapsing fever. This includes use of appropriate clothing and tick repellents when entering tick-infested areas.
• No vaccine is currently available.

Complications

• Louse-borne relapsing fever usually results in a JHR when treated with antibiotics, especially penicillin. JHR is characterized by acute exacerbation of symptoms, including the following:
• • Increased temperature
  • Chills
  • Rigors
  • Diaphoresis
  • Tachycardia
  • Hypotension

Prognosis

• The mortality rate of treated relapsing fever is than less than 5%.
• The mortality rate of untreated epidemic louse-borne disease is as high as 40%, whereas it is lower for tick-borne relapsing fever.

Patient Education

• Avoidance or elimination of arthropod vectors
• For excellent patient education resources, visit eMedicine's Bites and Stings Center. Also, see eMedicine's patient education article Ticks.

MISCELLANEOUS

Section 9 of 10  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• References

Medical/Legal Pitfalls

• Because of similar neurologic manifestations of the diseases and cross-reactive serologic assays, tick-borne relapsing fever can be complicated in regions where Lyme disease is prominent.

Special Concerns

• Myocarditis with associated arrhythmia, cerebral hemorrhage, and hepatic failure may occur.
• Relapsing fever during pregnancy is associated with increased maternal and infant morbidity and mortality.
• Multiple relapses may complicate the tick-borne infection, whereas a single relapse is more typical of louse-borne disease. Termination of the infection usually coincides with the development of type-specific borreliacidal antibodies.

REFERENCES

Section 10 of 10

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• References

• Cadavid D, Barbour AG. Neuroborreliosis during relapsing fever: review of the clinical manifestations, pathology, and treatment of infections in humans and experimental animals. Clin Infect Dis. Jan 1998;26(1):151-64. [Medline].
• Dworkin MS, Anderson DE Jr, Schwan TG. Tick-borne relapsing fever in the northwestern United States and southwestern Canada. Clin Infect Dis. Jan 1998;26(1):122-31. [Medline].
• Johnson WD Jr, Golightly LM. Borrelia species (Relasping Fever). In: Mandell GL, Bennett JE, Dolin R, eds. Mandell, Douglas, and Bennett's Principles and Practice of Infectious Diseases. 5th ed. Philadelphia, Pa: Churchill Livingstone; 2000:. 2502-4.
• Raoult D, Roux V. The body louse as a vector of reemerging human diseases. Clin Infect Dis. Oct 1999;29(4):888-911. [Medline].
• Shamaei-Tousi A, Martin P, Bergh A. Erythrocyte-aggregating relapsing fever spirochete Borrelia crocidurae induces formation of microemboli. J Infect Dis. Dec 1999;180(6):1929-38. [Medline].
• Trevejo RT, Schriefer ME, Gage KL. An interstate outbreak of tick-borne relapsing fever among vacationers at a Rocky Mountain cabin. Am J Trop Med Hyg. Jun 1998;58(6):743-7. [Medline].
• van Dam AP, van Gool T, Wetsteyn JC. Tick-borne relapsing fever imported from West Africa: diagnosis by quantitative buffy coat analysis and in vitro culture of Borrelia crocidurae. J Clin Microbiol. Jun 1999;37(6):2027-30. [Medline].

Article Last Updated: Dec 22, 2004