This is an infection due to the spirochete Borrelia recurrentis.

The spirochete is spread by a louse vector, and it is transmitted to humans when the louse is crushed and the spirochete makes contact with skin. The organism is able to penetrate intact skin.

This infection is now restricted primarily to Eastern Africa. However, several cases of this infection have been identified in African refugees in Europe.

Symptoms begin about 7 days after infection. The patient present with fever, myalgias, arthralgias, headache, and vomiting. Many patients will have hepatomegaly, splenomegaly, and abdominal pain. Less than 10% of patients have a rash. About one-third of patients will have a cough. About 30% of patients will have neurologic symptoms including altered mental status and meningismus. Patients may have jaundice if there is significant liver involvement with the infection. Symptoms can be severe, and the case-fatality rate may approach 40% in epidemics.

The first episode of fever typically lasts about 5 days. The afebrile interval is usually 9 days. The symptoms then recur. Antigenic shift is responsible for the relapsing symptoms. Febrile periods mark the time when the organism is dividing and able to be identified on blood smear.

As opposed to tick-borne relapsing fever, patients infected with louse-borne relapsing fever typically have only 1 or 2 episodes of relapsing symptoms.

Diagnosis can be made by identifying spirochetes on a blood smear. Serologic testing of acute and convalescent sera can be performed, but the testing is not specific. Polymerase chain reaction (PCR) testing of blood is available in specialized laboratories.

Treatment is with tetracycline, doxycycline, erythromycin, or penicillin. Antibiotic treatment may cause a Jarisch-Herxheimer reaction.