Cat Scratch Disease

What is Cat scratch?

Cat scratch disease is an infection transmitted to humans from cats by a scratch or other injury. It is caused by the bacterium Bartonella henselae. The infection passes without serious complications in most cases. Individuals who have HIV infection or are undergoing immunosuppressive therapy may develop a disseminated form of the disease. But neither form of the infection is life-threatening.

How is it diagnosed?

• History is of exposure to cats. Often a scratch or other skin injury is apparent. A primary lesion will develop within a few days at the site of the scratch. One to three weeks later, symptoms of a generalized infection will appear and the regional lymph nodes become enlarged. Fever and severe systemic symptoms may last for weeks.
• Physical exam may reveal an infected, scabbed ulcer or a small, circular, solid elevation of the skin with a central pus-filled region. The lymph nodes become enlarged, and may become filled with pus, occasionally draining spontaneously. Rashes of variable appearance may be seen.
• Tests: Microscopic examination with special staining of a smear from the infection will demonstrate the organism. Skin testing is usually positive. Lymph node biopsy shows granulomatous lesions, but biopsy is rarely indicated.

How is it treated?

Cat scratch disease usually resolves without therapy. The more severe disseminated form is treated with antibiotics.

Medications

Information	Brand	Generic	Label	Rating
	Minocin	Minocycline
	Zithromax	Azithromycin
	Doryx	Doxycycline

What might complicate it?

In rare instances, encephalitis may occur.

Predicted outcome

The prognosis for this infection is excellent. Full recovery is expected, even in individuals with impaired immune systems.

Alternatives

Lymphoma and other malignancies, tuberculosis, lymphogranuloma venereum, and acute bacterial infection may mimic the lymph node involvement. Cat scratch fever may be differentiated on the basis of nodal biopsy.

Appropriate specialists

Infectious disease specialist.

Last updated 17 November 2011