Sections View Full Chapter Figures Tables Videos Annotate Full Chapter Figures Tables Videos Supplementary Content +++ Key Features +++ Essentials of Diagnosis ++ Episodes of relapses fever, chills, malaise Occasional rash, arthritis, cough, hepatosplenomegaly, conjunctivitis Diagnosis suggested by direct microscopic identification of spirochetes in smears of peripheral blood Diagnosis confirmed with serologic testing +++ General Considerations ++ There are two forms: epidemic relapsing fever is transmitted to humans by body lice (Pediculus humanus) and endemic relapsing fever by soft-bodied ticks (genus Ornithodoros) Tick-borne relapsing fever is endemic in the western United States Transmission usually takes place during the warm months, when ticks are active and recreation or work brings people into contact with ticks Ticks are nocturnal feeders and remain attached for only 5–20 minutes; consequently, the patient seldom remembers a tick bite Rarely, neonatal relapsing fever results from transplacental transmission of Borrelia Both louse-borne and tick-borne relapsing fever may be acquired during foreign travel +++ Clinical Findings +++ Symptoms and Signs ++ Incubation period is 2–18 days Attack is sudden, with high fever, chills, sweats, tachycardia, nausea and vomiting, headache, myalgia, and arthralgia After 3–7 days, the fever falls Relapses occur at intervals of several days to weeks and duplicate the initial attack but become progressively less severe In louse-borne relapsing fever, there is usually a single relapse In tick-borne infection, 2–10 relapses occur Hepatomegaly, splenomegaly, pneumonitis, meningitis, and myocarditis may appear later in the course of the disease An erythematous rash may be seen over the trunk and extremities, and petechiae may be present Jaundice, iritis, conjunctivitis, cranial nerve palsies, and hemorrhage occur more commonly during relapses +++ Diagnosis ++ During febrile episodes, the patient's urine contains protein, casts, and occasionally erythrocytes Marked polymorphonuclear leukocytosis is present Spirochetes can be found in the peripheral blood by direct microscopy in approximately 70% of cases by darkfield examination or by Wright, Giemsa, or acridine orange staining of thick and thin smears Spirochetes are not found during afebrile periods Immunofluorescent antibody (or ELISA confirmed by Western blot) can help establish the diagnosis serologically +++ Differential Diagnosis ++ Malaria Leptospirosis Dengue Typhus Rat-bite fever Colorado tick fever Rocky Mountain spotted fever Collagen-vascular disease Any fever of unknown origin +++ Treatment ++ For children younger than age 8 years penicillin or erythromycin should be given for 10 days Older children may be given doxycycline +++ Outcome +++ Complications ++ Facial paralysis Iridocyclitis, optic atrophy Hypochromic anemia Pneumonia Nephritis Myocarditis, endocarditis Seizures +++ Prevention ++ Measures that decrease exposures to soft ticks and body lice will prevent most cases Soft-bodied ticks often are found in rodent burrows or nests, so decreasing rodent access to homes and eliminating rodents in the home is helpful Body-louse infestation can ... Your MyAccess profile is currently affiliated with '[InstitutionA]' and is in the process of switching affiliations to '[InstitutionB]'. Please click ‘Continue’ to continue the affiliation switch, otherwise click ‘Cancel’ to cancel signing in. Get Free Access Through Your Institution Learn how to see if your library subscribes to McGraw Hill Medical products. Subscribe: Institutional or Individual Sign In Username Error: Please enter User Name Password Error: Please enter Password Forgot Username? Forgot Password? Sign in via OpenAthens Sign in via Shibboleth