What are less common infectious causes of fever of unknown origin (FUO)?

Updated: May 17, 2021
  • Author: Sandra G Gompf, MD, FACP, FIDSA; Chief Editor: Michael Stuart Bronze, MD  more...
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The least common infectious causes of FUO are listed below.

Organ-based infectious causes of FUO are as follows:

  • Subacute bacterial endocarditis (SBE)
  • Tooth abscess
  • Chronic sinusitis/mastoiditis
  • Chronic prostatitis
  • Discitis
  • Vascular graft infections
  • Whipple disease
  • Multicentric Castleman disease (MCD)
  • Cholecystitis
  • Lymphogranuloma venereum (LGV)

Geographic and travel-related considerations for FUO are listed below.

Tickborne infections, as follows:

  • Babesiosis, Ehrlichiosis (southeast and central United States)
  • Anaplasmosis (northeast and north-central United States)
  • Tickborne relapsing fever (rodent-infested cabins)

Regional infections, as follows:

  • Histoplasmosis (Midwest United States, Ohio and Mississippi River Valleys, Central and South America, bat/bird droppings)
  • Coccidiomycosis (southwest United States)
  • Leptospirosis (tropics, freshwater swimming, triathlons, "mud run" races)
  • Visceral leishmaniasis (Latin America, Middle East)
  • Rat-bite fever (rat bite, food, or water)
  • Louse-borne relapsing fever (East African migrants, refugee camps)

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