About Tick and Louse-borne Relapsing Fevers

Key Points

  • Relapsing fever is caused by several species of Borrelia bacteria.
  • Relapsing fever Borrelia infections are categorized into three groups based on the animal that transmits the bacteria: soft tick relapsing fever (STRF), hard tick relapsing fever (HTRF), and louse-borne relapsing fever (LBRF).
Log cabin in the woods

Overview

Relapsing fever is an illness characterized by one or more episodes of fever, headache, and muscle pain that lasts several days and is separated by roughly a week of feeling well. Relapsing fever is caused by several species of Borrelia bacteria, which are distantly related to the bacteria that cause Lyme disease. Relapsing fever Borrelia infections are categorized into three groups based on the animal that transmits the bacteria:

There are differences in how severe the infection can be and where a person may be exposed.