Condition 101 About Relapsing Fever

What is the definition of Relapsing Fever?

Relapsing fever is a bacterial infection transmitted by a louse or tick. It is characterized by repeated episodes of fever.

What are the alternative names for Relapsing Fever?

Tick-borne relapsing fever; Louse-borne relapsing fever

What are the causes for Relapsing Fever?

Relapsing fever is an infection caused by several species of bacteria in the borrelia family.

There are two major forms of relapsing fever:

  • Tick-borne relapsing fever (TBRF) is transmitted by the ornithodoros tick. It occurs in Africa, Spain, Saudi Arabia, Asia, and certain areas in the western United States and Canada. The bacteria species associated with TBRF are Borrelia duttoni, Borrelia hermsii, and Borrelia parkerii.
  • Louse-borne relapsing fever (LBRF) is transmitted by body lice. It is most common in Asia, Africa, and Central and South America. The bacteria species associated with LBRF is Borrelia recurrentis.

Sudden fever occurs within 2 weeks of infection.

  • In TRBF, multiple episodes of fever occur, and each may last up to 3 days. People may not have a fever for up to 2 weeks, and then it returns.
  • In LBRF, the fever commonly lasts 3 to 6 days. It is often followed by a single, milder episode of fever.

In both forms, the fever episode may end in "crisis." This consists of shaking chills, followed by intense sweating, falling body temperature, and low blood pressure. This stage may result in death.

In the United States, TBRF often occurs west of the Mississippi River, particularly in the mountains of the West and the high deserts and plains of the Southwest. In the mountains of California, Utah, Arizona, New Mexico, Colorado, Oregon, and Washington, infections are usually caused by Borrelia hermsii and are often picked up in cabins in forests. The risk may now extend into the southeastern United States.

LBRF is mainly a disease of the developing world. It is currently seen in Ethiopia and Sudan. Famine, war, and the movement of refugee groups often results in LBRF epidemics.

What are the symptoms for Relapsing Fever?

Symptoms of relapsing fever include:

  • Bleeding
  • Coma
  • Headache
  • Joint aches, muscle aches
  • Nausea and vomiting
  • Sagging on one side of the face (facial droop)
  • Stiff neck
  • Sudden high fever, shaking chills, seizure
  • Vomiting
  • Weakness, unsteady while walking

What are the current treatments for Relapsing Fever?

Antibiotics including penicillin and tetracycline are used to treat this condition.

What is the outlook (prognosis) for Relapsing Fever?

People with this condition who have developed a coma, heart inflammation, liver problems, or pneumonia are more likely to die. With early treatment, the death rate is reduced.

What are the possible complications for Relapsing Fever?

These complications may occur:

  • Drooping of the face
  • Coma
  • Liver problems
  • Inflammation of the thin tissue that surrounds the brain and spinal cord
  • Inflammation of the heart muscle, which may lead to irregular heart rate
  • Pneumonia
  • Seizures
  • Stupor
  • Shock related to taking antibiotics (Jarisch-Herxheimer reaction, in which the rapid death of very large numbers of borrelia bacteria causes shock)
  • Weakness
  • Widespread bleeding

When should I contact a medical professional for Relapsing Fever?

Contact your health care provider right away if you develop a fever after returning from a trip. Possible infections need to be investigated in a timely manner.

How do I prevent Relapsing Fever?

Wearing clothing that fully covers the arms and legs when you are outdoors can help prevent TBRF infection. Insect repellent such as DEET on the skin and clothing also work. Tick and lice control in high-risk areas is another important public health measure.


Horton JM. Relapsing fever caused by borrelia species. In: Bennett JE, Dolin R, Blaser MJ, eds. Mandell, Douglas, and Bennett's Principles and Practice of Infectious Diseases, Updated Edition. 8th ed. Philadelphia, PA: Elsevier Saunders; 2015:chap 242.

Petri WA. Relapsing fever and other borrelia infections. In: Goldman L, Schafer AI, eds. Goldman-Cecil Medicine. 25th ed. Philadelphia, PA: Elsevier Saunders; 2016:chap 322.

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Clinical Trials For Relapsing Fever

Clinical Trial
  • Status: Recruiting
  • Phase: N/A
  • Intervention Type: Other
  • Participants: 220
  • Start Date: November 20, 2020
Early Termination of Empirical Antibiotics in High-risk Febrile Neutropenia in Children With Cancer: an Open-label, Randomised, Controlled Trial