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Relapsing Fever

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Disease Details

Incubation Period:

  • 5 - 15 days

Transmission Type(s):

Disease Reservoirs

Disease Agents

About Relapsing Fever

Bacteria that cause Tickbourne Relapsing Fever (TBRF) are transmitted to humans through the bite of infected “soft ticks” of the genus Ornithodoros. Soft ticks differ in two important ways from the more familiar “hard ticks” (e.g., the dog tick and the deer tick). First, the bite of soft ticks is brief, usually lasting less than half an hour. Second, soft ticks do not search for prey in tall grass or brush. Instead, they live within rodent burrows, feeding as needed on the rodent as it sleeps.

Humans typically come into contact with soft ticks when they sleep in rodent-infested cabins. The ticks emerge at night and feed briefly while the person is sleeping. The bites are painless, and most people are unaware that they have been bitten. Between meals, the ticks may return to the nesting materials in their host burrows.

Lousebourne Relapsing Fever (LBRF) is caused by a spiral-shaped bacteria, Borrelia recurrentis, which is transmitted from human to human by the body louse. LBRF outbreaks most commonly occur in conditions of overcrowding and social disruption.


In the United States, TBRF occurs most commonly in 14 western states: Arizona, California, Colorado, Idaho, Kansas, Montana, Nevada, New Mexico, Oklahoma, Oregon, Texas, Utah, Washington, and Wyoming.

LBRF is not presently found in North America.


Relapsing fever is characterized by episodes of fever lasting several days, followed by an interval without fever, followed by another episode of fever. This process can recur from 1 to 4 times. Along with fever, patients may experience generalized body aches, muscle pain, joint pain, headache, nausea, vomiting, anorexia, dry cough, light sensitivity, rash, neck pain, eye pain, confusion, and dizziness.

Relapsing Fever Prevention

  • Avoid sleeping in rodent-infested buildings.
  • Prevent tick bites by using insect repellent containing DEET (on skin or clothing) or permethrin (applied to clothing or equipment).
  • Rodent-proof buildings in areas where the disease is known to occur.
  • Consult a licensed pest control specialist who can safely:
    • Identify and remove any rodent nesting material from walls, attics, crawl spaces, and floors.
    • Treat "cracks and crevices" in the walls with pesticide.
    • Provide additional pesticide treatments as necessary to effectively rid the building of the soft ticks.

Read More

Read more about Relapsing Fever at the Centers for Disease Control (CDC) Website