An infection that is caused by certain species of Rickettsia or Borrelia, which are transmitted to humans from infected lice; it is characterized by sudden fever, chills, headaches, myalgia, arthralgia, nausea, and possibly a rash. Symptoms usually persist for two to nine days, then disappear, with recurrence after several weeks if the patient remains untreated. The disease is louse-borne relapsing fever (MONDO_0001620). Also known as: Relapsing fever, louse-borne.