• Knowledgebase: Information on Specific Illnesses

    Here you will find discussions of specific illnesses and their management.

    63. Cat Scratch Disease - Top

    Definition
    An infectious illness associated with cat scratches, bites, or exposure to cat saliva, causing chronic swelling of the lymph nodes (lymphadenopathy).

    Causes, Incidence and Risk Factors
    Cat scratch disease is caused by a gram negative bacillus (a type of bacteria) presently referred to as CSD bacillus or Bartonella henselae. The disease is spread through contact with an infected cat, as a result of a cat bite or scratch, or contact with cat saliva on broken skin or the conjunctiva of the eye.
    Lymph node swelling begins about 2 to 3 weeks after exposure and may persist for months. Swelling may occur at the site of the initial infection followed by enlarged lymph nodes along the lymph drainage route from the injury site. Occasionally nodes may form a fistula through the skin and drain. Cat scratch disease is possibly the most common cause of chronic lymph node swelling in children. Until now the disease often went unrecognized because of the difficulty in testing. Recently however, the B. henselae IFA test was shown to be highly sensitive and specific for the detection of infection caused by B. henselae and for the diagnosis of cat scratch disease.


    Symptoms
    a history of contact with a cat (or dog on rare occasion) with a scratch or injury.
    Common

    papule or pustule at site of injury (inoculation), usually the first sign
    swelling of the lymphnodes (adenopathy) occurs in the area near where the skin was infected (bitten, scratched, etc.)
    Fever in approximately one third of patients
    fatigue
    malaise
    headache
    Less Common

    anorexia
    Weight loss
    Splenomegaly
    Sore throat
    Draining lymph nodes
    Signs And Tests
    A scratch or injury and a history of contact with a cat (or dog on rare occasion) indicates that cat scratch disease is the likely cause of the lymph node swelling. In some cases, physical examination also shows an enlarged spleen (splenomegaly).
    Tests used in the diagnosis of cat scratch disease:

    B. henselae IFA test (uses fluid or tissue from a lymph node)
    a lymph node biopsy to rule out other causes of swollen glands
    a positive CSD skin test



    Treatment
    Generally, cat scratch disease leads a relatively benign course. Treatment, other than reassurance, is not usually recommended. However, in severe cases treatment with antibiotics is helpful. Effective antibiotics include:

    erythromycin (E-Mycin)
    sulfamethoxazole and trimethoprim
    doxycycline
    rifampin combined with another agent
    In AIDS patients and in other people who have suppressed immune systems cat scratch disease is not benign, and treatment with antibiotics is recommended.

    Expectations (Prognosis)
    In children with normal immune systems, spontaneous healing with full recovery is the norm. In immunocompromised people treatment with antibiotics generally leads to recovery.
    - Updated: March 5, 2001

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    • James L Horwitz, MD

    David C. Thomas, MD

    Barbara Lindberg, PNP