Cat Scratch Disease

Cat scratch disease is an infection by Bartonella henselae bacteria. It causes swollen glands, usually after a scratch or a bite from a cat.


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Bartonella henselae


Where Is Bartonella henselae Found?

Bartonella henselae, the bacterium that causes cat scratch disease, is found all over the world. Cats and kittens carry the bacterium in their saliva. Although the infection does not make cats or kittens sick, they can transmit the infection to people, most often through a bite or a scratch. People cannot pass along the infection to other people.

What Happens When People Get Cat Scratch Disease?


Cat scratch disease usually results in a sore appearing at the site of the bite or scratch a few days afterward, followed a week or two later by swelling of the lymph nodes * (swollen glands) near the bite or the scratch as the body's immune system fights off the infection. Adults will sometimes run a low fever, or have a headache and joint pain, or feel more tired than usual. Most people get better within about three weeks. People with weakened immune systems are at risk for more serious complications, which may include:

  • retinitis (re-ti-NY-tis): inflammation of the retina of the eye, which can cause blindness
  • encephalitis (en-sef-a-LY-tis): inflammation of the brain
  • seizures
  • infections of the liver, spleen, bones, or other organs.


The doctor usually starts with a physical exam and a medical history, which should include information about contact with cats. The doctor may diagnose cat scratch disease if the person has fever, is feeling unwell, and has enlarged lymph nodes accompanied by a blister. Other ways to identify the disease include testing the blood for antibodies to Bartonella or performing a biopsy on an enlarged lymph node.


Most people get better on their own. The doctor may prescribe antibiotics to help fight the bacterial infection, and the doctor may drain fluid from lymph nodes that are severely enlarged. People with weakened immune systems need continuing care from their doctors to minimize the risk of complications.

Preventing Cat Scratch Disease

It is important to teach children to stay away from stray cats and unknown cats. It is also important to teach them to be careful with their own pets, who may bite and scratch when provoked. Whenever cats bite or scratch people, it is a good idea to check with a doctor (about the person) and with a veterinarian (about the pet).

* lymph nodes are bean-sized round or oval masses of immune system tissue that filter bodily fluids before they enter the bloodstream, helping to keep out bacteria and other undesirable substances.

Did You Know?

  • There are more than 60 million pet cats in the United States.
  • Approximately 24,000 people get cat scratch disease in the U.S. each year.
  • Kittens transmit cat scratch disease to people more often than adult cats do.
  • Kittens who have fleas are 29 times likelier to carry Bartonella henselae bacteria than kittens without fleas.
  • Fewer than 5 percent of people with cat scratch disease develop severe symptoms.


The Association of State and Territorial Directors of Health Promotion and Public Health Education (ASTDHPPHE) posts a fact sheet about cat scratch disease at its website. (The Nemours Foundation) is a website that posts fact sheets about many different conditions, including cat scratch disease.

American Academy of Family Physicians, 8880 Ward Parkway, Kansas City, MO 64114-2797. The AAFP's website posts fact sheets about many different conditions, including cat scratch disease.
Telephone 800-274-2237

See also
Bacterial Infections

Also read article about Cat Scratch Disease from Wikipedia

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