Cat Scratch Disease (CSD) is an infection caused by Bartonella henselae bacteria. In
healthy people, it most often causes a swollen lymph node and mild illness. The
domestic cat is the animal that carries the CSD bacteria, which are transmitted between
cats by the cat flea.

People can get CSD when they are bitten or scratched by a cat with a flea infestation.
The feces of cat fleas contain the CSD bacteria. A person can become infected when
the flea feces enter a break in the skin during a cat scratch or bite. Direct contact with
cat fleas is unlikely to be a cause of infection. Infected cats usually do not look sick.

The most frequent symptom of CSD is a swollen lymph node, usually occurring in the
head, neck, or arms. It may take one to four weeks for lymph node swelling to appear
after contact with an infected cat. Swelling, redness, and pain that occur at the
bite/scratch site within one to two days is probably not CSD. Swollen lymph nodes
often take 2 to 4 months to return to normal, with or without antibiotic treatment. In
addition, people with CSD can have headache, fever, fatigue, and a poor appetite.
Rare complications of CSD in people with normal immune systems include inflammation
of the eyes, heart, or brain. People with compromised immune systems, such as organ
transplant patients, cancer patients, or those with HIV/AIDS, are more likely to have
severe illness if infected with the CSD bacteria.

If you have been scratched or bitten by a cat, and develop symptoms that look like
CSD, your doctor may order a blood test to help determine if you have CSD. Your
doctor will decide whether you will need to be treated with antibiotics.

About 22,000 to 24,000 cases of CSD occur in the United States every year and about
2,000 people are hospitalized as a result of the infection.

About 40 percent of cats carry the CSD bacteria at some time in their lives. However,
young cats and kittens are more likely than older cats to be infected and pass the
bacteria on to people.

To prevent CSD, people should: