Cat scratch disease

Alternative names
CSD; Cat scratch fever; Bartonellosis

Definition
Cat scratch disease is an infectious illness caused by the bacteria Bartonella, believed to be transmitted by cat scratches, bites, or exposure to cat saliva. This leads to swelling of the lymph nodes (lymphadenopathy) near the site of the scratch or bite.

Causes, incidence, and risk factors

Cat scratch disease is caused by 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 one of the common causes of chronic lymph node swelling in children. Until now, the disease often went unrecognized because of the difficulty in testing.

Recently however, the Bartonella henselae IFA test was shown to be highly sensitive and specific for the detection of infection caused by Bartonella henselae and for the diagnosis of cat scratch disease.

Symptoms

     
  • A history of contact with a cat

Common

     
  • Papule or pustule at site of injury (inoculation), usually the first sign  
  • Swelling of the lymph nodes (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

     
  • Loss of Appetite  
  • Weight loss  
  • Enlarged Spleen  
  • Sore throat  
  • Draining lymph nodes

Signs and tests
A scratch or injury and a history of contact with a cat 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:

     
  • Positive Bartonella serology  
  • Bartonella 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 is not serious. Treatment, other than reassurance, is not usually recommended. However, in severe cases treatment with antibiotics can be helpful.

In AIDS patients and in other people who have suppressed immune systems, cat scratch disease is more serious, 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.

Complications

     
  • Parinaud’s syndrome  
  • Encephalopathy  
  • Neuroretinitis  
  • Osteomyelitis

Calling your health care provider
Call your health care provider if you have enlarged lymph nodes and a history of exposure to a cat.

Prevention
Avoiding contact with cats prevents the disease. Where this is not feasible, good hand washing after playing with a cat, avoiding scratches and bites, and avoiding cat saliva minimizes the risk of infection.

Johns Hopkins patient information

Last revised: December 5, 2012
by Potos A. Aagen, M.D.

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