🦠microbiology review

Relapsing fever

Written by the Fiveable Content Team • Last updated September 2025
Written by the Fiveable Content Team • Last updated September 2025

Definition

Relapsing fever is a bacterial infection characterized by recurring episodes of fever, headache, muscle and joint aches, and nausea. It is caused by spirochetes from the genus Borrelia, transmitted through lice or ticks.

5 Must Know Facts For Your Next Test

  1. Relapsing fever is typically caused by Borrelia recurrentis (louse-borne) or various tick-borne Borrelia species.
  2. The disease is marked by cycles of fever lasting several days followed by periods without fever.
  3. Diagnosis often involves blood smears during febrile episodes to detect spirochetes.
  4. Treatment generally includes antibiotics such as doxycycline or erythromycin.
  5. Complications can include neurological issues, myocarditis, and liver dysfunction.

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