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FINDINGS: This infection is caused by spirochetes transmitted by lice or ticks. In the typical case, several days of fever are followed by a fever-free period and then one or more episodes of relapsing fever. A transitory petechial rash is common early in the illness. GI symptoms are common. Patients with B vitamin deficiencies are at greater risk for neuritis and encephalitis. Hematuria and epistaxis have been reported. [CCDM, p. 450-3] Other findings may include mild leukocytosis, tachycardia, subconjunctival hemorrhages, vomiting, arthralgia, and delirium. Later in the course, jaundice, hepatomegaly, splenomegaly, uveitis, and myocarditis may occur. [Merck Manual, p. 1482; Current Consult, p. 1166] Both the tick-borne and louse-borne forms have intervals between fevers of 4-14 days. Other symptoms accompanying the fever are headache, neck stiffness, cough, arthralgia, myalgia, delirium, dizziness, and coma. Splenomegaly is common, and hepatomegaly and hepatitis occurs in about 50% of louse-borne cases and 10% of tick-borne cases. Patients with louse-borne disease may have petechiae, epistaxis, and anemia. Patients with tick-borne disease are more likely to have neurological complications including meningoencephalitis, cranial neuritis, radiculitis, myelitis, and iridocyclitis. Myocarditis and pulmonary edema may be the cause of death in both forms. [Guerrant, p. 499-506] Among the less common findings are lymphadenopathy, rales, and pneumonia. Hemorrhage, including hemoptysis and hematemesis, is common but rarely severe. [PPID, p. 2796] EPIDEMIOLOGY: Louse-borne relapsing fever is no longer reported in the USA. Cases are reported in Guatemala and the Andean highlands. Ethiopia has an estimated 10,000 cases per year. Migrant workers and soldiers in the field are at risk for the louse-borne disease. A few cases of tick-borne relapsing fever are reported periodically in western USA and Canada. Ticks that carry the spirochetes usually feed at night and then leave the host. Wild rodents are reservoirs for the tickborne disease. [CCDM, p. 450-3; ID, p. 1470-2] |
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