infectious diseases
Relapsing Fever
Key Points
Relapsing fever is caused by severalBorreliaspecies and is transmitted by lice or ticks. Patients have sudden chills, high fever, severe headache, nausea, vomiting, muscle and joint pain, and often delirium and/or a rash on the trunk and extremities; jaundice, hepatomegaly, splenomegaly, myocarditis, and heart failure may occur, especially in louse-borne disease. Untreated patients have 2 to 10 relapses at 1- to 2-week intervals; relapses manifest with a sudden return of fever and often arthralgia and all the former symptoms and signs, although they may be less severe. Diagnose using darkfield microscopy or Wright- or Giemsa-stained thick and thin blood smears; serologic tests are unreliable. Treat withtetracycline,doxycycline, orerythromycin. 