Bartonella Infections



  • Fastidious intracellular anaerobic gram-negative bacilli:
    • >30 distinct species, at least 13 known to cause disease in humans (1,2)
    • Bartonella henselae and Bartonella quintana are most common in North America.
  • Infections manifest in two broad categories:
    • Localized skin lesions and prominent regional lymphadenitis (cat-scratch disease [CSD])
    • Bacteremia with localized vascular lesions in various organs with potential for persistent disseminated infection
  • System(s) affected: cardiovascular, gastrointestinal (GI), heme/lymphatic/immunologic, hepatic, musculoskeletal, nervous, pulmonary, skin/exocrine, ocular, renal (rare)
  • Synonym(s): bartonellosis; CSD; trench fever; Carrión disease; Oroya fever



  • CSD: 9/100,000 annually in the United States (~25,000 cases)
  • Carrión disease: 12.7/100 person-years in endemic areas (Andes Mountains); rare in the United States
  • Endocarditis: estimated 3–4% of cases
  • Others: unknown


  • Worldwide
  • Seroprevalence studies of B. henselae suggest that many childhood infections are asymptomatic:
    • Seroprevalence in domestic cats is 25–51%.
    • Highest in fall and winter
  • Seroprevalence of B. quintana in homeless populations is ~10%.

Etiology and Pathophysiology

  • Erythrocyte and endothelial cell invasion
  • In immunocompetent hosts, disease progresses to granuloma and suppuration of lymph nodes.
  • In immunocompromised hosts, can lead to angiogenesis with mixed inflammatory cell infiltrate

No known genetic predisposition

Risk Factors

  • Vector exposure with cutaneous inoculation
    • B. henselae (CSD): domestic cat scratch/bite or transmitted horizontally from cat fleas and ticks
      • Natural reservoir is the domestic cat.
      • Transmission from dogs has been reported.
    • B. quintana (trench fever): human body louse, most common in alcohol-dependent homeless males, possible flea (from rats and cats) vector
    • Bartonella bacilliformis (Carrión disease): Lutzomyia sandflies from Andean South America
  • Cell-mediated immune dysfunction (particularly in bacillary angiomatosis/bacillary peliosis)
    • HIV infection (CD4+ lymphocyte count <100/μL)
    • Chronic steroid use, immunosuppression, or alcohol abuse
  • Vector control
    • Treat pets with regular flea/tick medications (3)[B].
    • Avoid stray cats (3)[B].
    • Avoid cat scratches (no rough play with cats); immediately wash cat bite and scratches (3)[B].
    • Do not allow cats to lick open wounds (3)[B].
    • Treat body louse infestations (3)[A].
    • Severely immunosuppressed patients should weigh risks of cat ownership and consider avoiding cats <1 year of age (3)[B].
  • No evidence for effectiveness of postexposure chemoprophylaxis (3)[C]
  • No evidence for routine testing of cats

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