Cat Scratch Disease

Cat Scratch

We have discussed lymphadenopathy previously and last week we spoke of a specific condition that is associated with enlarged lymph nodes: Kawasaki Disease and Incomplete Kawasaki Disease.  While Kawasaki Disease is fun to think about, there is another condition that leads to lymphadenopathy much more commonly: Cat Scratch Disease.

Cat Scratch Disease Basics

  • Caused by Bartonella henselae.
  • Associated with Cat Scratch (especially kittens) or Flea bite (flea on the cat).
  • Bartonella henselae is a slow-growing, gram-negative bacilli (in case you forgot from medical school… like I did).
  • Cat Scratch Disease is very common in the US (apparently we like cats).
    • ~25,000 cases / year
    • Occurs in all ages, but most common in kids < 10 years of age.
    • It is one of the most common causes of chronic lymphadenopthy in children.


  • >90% will have lymphadenopathy.
    • Lymphadenoathy adjacent to the location of the scratch.
    • Usually large (1 – 5 cm).

    Only ~50% will have a history of a cat scratch or bite.

    • The Cat Scratch may have occurred several weeks before the development of lymphadenopathy (usually 1-4 weeks).

    ~33% – 60% will have fevers.

  • Many will have other systemic symptoms (malaise, fatigue, headache, etc).
  • May become complicated:
    • Parinaud Oculoglandular Syndrome
      • Conjunctival involvement and preauricular lymphadenopathy.
    • Aseptic meningitis
    • Encephalitis
    • Hepatitis
    • Hepatic and Splenic microabscesses.
    • Persistent fever


  • Primarily a clinical diagnosis.
  • May consider testing in atypical cases or prolonged course.
  • Indirect fluorescent antibody test for antibodies against organism.
  • PCR
  • Histology of lymph node.


  • Primarily symptomatic as Cat Scratch Disease is a self-limited infection primarily.
  • Lymphadenopathy can persist for multiple months.
  • Antibiotics:
    • No significant research demonstrating benefit; however, consider in:
      • Immunocompromised host
      • Acutely ill with systemic symptoms
      • Large and painful nodes or hepatosplenomegaly
  • Azithromycin is usually the 1st option.
  • Rifampin, Bactrim, or Cipro are also options.

Other Considerations

  • Malignancy
  • Bacterial adenitis
  • Other weird infections (ex, Tularemia, Brucellosis, Histoplasmosis, Toxoplasmosis, LGV, myobacterial infection).

Overall, when evaluating the child with Lymphadenopathy, naturally consider oncologic processess, but often asking whether the child has been scratched by a cat can be quite helpful!


Sean M. Fox
Sean M. Fox
Articles: 583


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