Louse-borne relapsing fever
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.
A68.0 – Louse-borne relapsing fever
14683004 – Louse-borne relapsing fever
Differential Diagnosis & Pitfalls
- – This febrile illness is always important to exclude in patients from areas where malaria is present. It may occur at the same time as other infections including louse-borne relapsing fever. Thick and thin blood smears and malaria antigen testing should be performed.
- – Another infection spread by the human body louse. Relapse of symptoms does not typically occur. Serologic testing is available for the etiologic agent, Rickettsia prowazekii.
- – An infection that is typically acquired in areas with poor sanitation. The illness does not have the typical relapsing symptoms seen in louse-borne relapsing fever. Diagnosis can be made by blood culture.
- – Another infection caused by a pathogenic spirochete. Patients acquire the infection after exposure to contaminated water and soil. Diagnosis can be made by culture, serology, or PCR.
- – Although uncommon, a relapse of symptoms may occur with this infection. Diagnosis can be made by serology or PCR.