Relapsing fever is bacterial infection characterized by recurring episodes of fever, headache, muscle and joint aches, and nausea. It is caused by certain species of Borrelia spirochetes. There are two types of relapsing fever:
- Tick-borne relapsing fever (TBRF)
- Louse-borne relapsing fever (LBRF)
Tick-borne relapsing fever occurs in the western United States and is usually linked to sleeping in rustic, rodent-infested cabins in mountainous areas. Louse-borne relapsing fever is transmitted by the human body louse and is generally restricted to refugee settings in developing regions of the world.