causes of fever of unknown origin

Etiology

• infectious
  • localized pyogenic infection
    • appendicitis
    • cat-scratch disease
    • cholangitis
    • cholecystitis
    • abscess
      • lesser sac, liver, pancreas, perinephric, intrarenal, prostate, subphrenic, tuboovarian
    • diverticulitis
    • mesenteric lymphadenitis
    • osteomyelitis
    • pelvic inflammatory disease
    • renal malcoplakia
    • suppurative thrombophlebitis
  • intravascular infection
    • bacterial aortitis
    • bacterial endocarditis
      • especially HACEK group, Bartonella, Legionella, Coxiella burnetii, Chlamydia psittaci & fungi
      • hold blood cultures for 2 weeks
  • vascular catheter infection
  • systemic bacterial infection
    • Bartonellosis
    • Brucellosis
    • Campylobacter
    • cat-scratch disease/bacillary angiomatosis
    • gonococcemia
    • Legionnaires' disease
    • leptospirosis
    • listeriosis
    • Lyme disease
    • melioidosis
    • meningococcemia
    • rat-bite fever
    • relapsing fever (louse-borne Borrelia)
    • Salmonella
    • syphilis
    • tularemia
    • typhoid fever
    • Vibrio
    • Yersinia
  • mycobacterial infection
    • Mycobacterium avium intracellulare (MAI)
    • other atypical Mycobacterial species
    • tuberculosis
  • fungal infection
    • aspergillosis
    • blastomycosis
    • candidiasis
    • coccidioidomycosis
    • cryptococcosis
    • histoplasmosis
    • mucormycosis
    • paracoccidioidomycosis
    • sporotrichosis
  • other bacterial infections
    • actinomycosis
    • nocardiosis
    • Whipple's disease
  • rickettsial infections
    • ehrlichiosis
    • murine typhus
    • Q fever
    • rickettsialpox
    • Rocky Mountain spotted fever
  • mycoplasma infections
  • chlamydial infections
    • lymphogranuloma venereum
    • psittacosis
    • Chlamydia pneumoniae (TWAR)
  • viral infections
    • Colorado tick fever
    • Coxsackie virus group B infection
    • cytomegalovirus infection
    • dengue
    • Epstein-Barr virus infection
    • hepatitis A, hepatitis B, hepatitis C, hepatitis D, hepatitis E
    • human immunodeficiency virus infection (HIV)
    • lymphocytic choriomeningitis
    • parvovirus B19 infection
  • parasitic infections
    • amebiasis
    • babesiosis
    • Chagas' disease
    • leishmaniasis
    • malaria
    • Pneumocystis carinii
    • strongylodiasis
    • toxocariasis
    • toxoplasmosis
    • trichinosis
  • presumed infection, agents unidentified
    • Kawasaki's disease
    • Kikuchi's disease (necrotizing lymphadenitis)
• neoplasms
  • malignant
    • colon cancer
    • hepatoma
    • Hodgkin's disease
    • immunoblastic lymphadenopathy
    • leukemia
    • lymphomatoid granulomatosis
    • malignant histiocytosis
    • nephroma
    • non-Hodgkin's lymphoma
    • pancreatic cancer
    • sarcoma
    • lung cancer
  • benign
    • atrial myxoma
    • renal angiolipoma
    • cysts
      • dermoid cyst
      • 4th ventricle cyst
    • hypernephroma
• connective tissue & hypersensitivity disorders
  • adult Still's disease
  • Behcet's disease
  • erythema multiforme
  • erythema nodosum
  • giant cell arteritis/polymyalgia rheumatica
  • hypersensitivity pneumonitis
  • hypersensitivity vasculitis
  • mixed connective tissue disease
  • polyarteritis nodosa
  • relapsing polychondritis
  • rheumatic fever
  • rheumatoid arthritis
  • systemic lupus erythematosus
  • Takayasu's arteritis
  • Weber-Christian disease
  • Wegener's granulomatosis
  • immune complex nephritis
• granulomatous diseases
  • Crohn's disease
  • idiopathic granulomatous hepatitis
    • liver function may be normal
  • midline granuloma
  • sarcoidosis
  • xanthogranulomatosis
• inherited & metabolic disorders
  • adrenal insufficiency
  • cyclic neutropenia
  • deafness, urticaria & amyloidosis
  • Fabry's disease
  • familial Mediterranean fever
  • hyper-immunoglobulin D & periodic fever
  • type V hypertriglyceridemia
• thermoregulatory disorders
  • central
    • brain tumor
    • cerebrovascular accident
    • encephalitis
    • hypothalamic dysfunction
  • peripheral
    • hyperthyroidism
    • pheochromocytoma
• miscellaneous conditions
  • aortic dissection
  • drug fever
  • gout & pseudogout
  • hematoma
  • hemolytic disease/hemoglobinopathies
  • Laennec's cirrhosis
  • postmyocardial infarction syndrome
  • recurrent pulmonary emboli
  • subacute thyroiditis (de Quervian's thyroiditis)
  • tissue infarction/necrosis
  • aspiration
    • Zenker's diverticulum
    • lipid (nasal or lip emulsions)
  • foreign bodies
• factitious fevers
• habitual hyperthermia (exagerrated circadian rhythm
• neutropenic fever
• HIV-associated fever

Additional terms

• fever of unknown origin (FUO)