Relapsing fever is carried by lice and ticks.

Relapsing fever can be treated with effective antibiotics. Several days of fever are followed by a fever-free period and then one or more episodes of relapsing fever. GI symptoms are common. Tick-borne: worldwide; Louse-borne: endemic in central & east Africa and in high-altitude South America.

10 (US); 200,000 (Global)
Borrelia recurrentis infection (louse-borne); Borrelia species infection (tick-borne); Epidemic relapsing fever (louse-borne);
Louse-borne: 5-15 days (usually 8 days); Tickborne: 2-18 days (usually 7 days); [CCDM]
Relapsing fever (fever for 2-7 days alternating with no fever for 4-14 days); Also, patients have flu-like symptoms (headache, myalgia, arthralgia and abdominal pain). [CCDM, p. 510]
Standard; "Not transmitted from person to person." [CDC 2007 Guideline for Isolation Precautions] Delouse and remove ticks; [CCDM]
In the typical case, several days of fever are followed by a fever-free period and then one or more episodes of relapsing fever. GI symptoms are common. Patients with B vitamin deficiencies are at greater risk for neurological involvement. [CCDM, p. 510] 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 thrombocytopenia. A small papule with a central eschar may develop at the site of the tick bite. [Guerrant, p. 295-8] In louse-borne disease, platelet counts are <50,000/mm3 in up to 90% of cases. Spirochetes are visible on blood smears during febrile episodes in about 70% of patients. [Cecil, p. 1997] Relapsing fever is relapsing because of variations in borrelial surface antigens. Each relapse occurs when the organism changes its surface antigens and evades the immune system. Other infections that have biphasic or relapsing fever are Colorado tick fever, yellow fever, dengue fever, lymphocytic choriomeningitis, brucellosis, malaria, leptospirosis, chronic meningococcemia, rat-bite fever, echovirus 9, and Bartonella species. [Harrison ID, 2nd Ed, p. 716-20]

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. 297-8] Up to 80% of patients with tick-borne disease have neurological findings. After the initial high fever, patients may develop headache, lethargy, meningitis, seizures, and coma. Patients may die from shock, pulmonary edema secondary to myocarditis, or a Jarisch-Herxheimer reaction. [Cohen, p. 1106-7]

For untreated cases, fatality rates are 2-10%.This infection is caused by spirochetes transmitted by lice or ticks. Wild rodents are reservoirs for the tickborne disease. [CCDM, p. 510-13] In typical tick-borne cases in the US, patients have visited western national parks (elevation of 1500 to 8000 feet) and slept in cabins infected with rodents. The tick feeds at night and is attached for only 15 minutes. Most patients do not recall a tick bite. Animal reservoirs are wild rodents (mice, rats, squirrels, and chipmunks) for tick-borne and none for louse-borne). [Cecil, p. 1996-7]
Darkfield exam of fresh blood; Stained blood smear; Special cultures; [CCDM] Wright- or Giemsa stained blood obtained during fever; Reference labs: 4 X serological rise, culture, and PCR techniques; [ABX Guide: Borrelia species]
Tick-borne: worldwide; Louse-borne: endemic in central & east Africa (Ethiopia, Somalia, Chad, & the Sudan) and in high-altitude South America (Bolivia & Peru); [Cecil, 1996-7]
  • >arthralgia
  • >fatigue, weakness
  • >fever
  • >fever, biphasic or relapsing
  • >myalgia
  • E epistaxis
  • G abdominal pain
  • G blood in stool
  • G diarrhea
  • G hematemesis
  • G hepatomegaly
  • G jaundice
  • G liver function test, abnormal
  • G nausea, vomiting
  • H leukocytosis
  • H leukopenia
  • H lymphadenopathy
  • H splenomegaly
  • H thrombocytopenia
  • N confusion, delirium
  • N headache
  • N lethargy
  • N paresthesia
  • N seizure
  • N stiff neck
  • O conjunctivitis, acute
  • R cough
  • S papules or plaques
  • S petechiae and ecchymoses
  • S rash (exanthem)
  • U hematuria
  • *ARDS
  • *bleeding tendency
  • *cranial neuropathy
  • *encephalitis
  • *hepatitis
  • *meningitis
  • *myelitis
  • *myocarditis
  • *paralysis
  • *pneumonia
  • *pulmonary edema
  • *shock
  • *stupor, coma
  • *uveitis




Lice, Ticks
Rodents, Human
  • Travel to endemic area
  • Work or play in tick-infested area
Antibiotic treatment may cause the Jarisch-Herxheimer reaction (fever, rigors, hypotension, and leukopenia); [PPID, p. 2909]
1. (US) sporadic tick-borne cases in western US and Canada; [CCDM, p. 511] Guesstimate = 10 case/yr;
2. (Global) Risk for travelers is low; [Public Health England website] About 10,000 cases/year occur in Ethiopia; [ID, p. 1471] In top 10 bacterial infections causing admissions and death in Ethiopia (lice-borne) and Senegal/Tanzania (tick-borne); [CCDM, p. 511] Guesstimate: assume that there are 20 other countries with the same rate as Ethiopia = 200,000;