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Cat Scratch Disease

Cat Scratch Disease

What Is Cat Scratch Disease?

Who Gets Cat Scratch Disease?

What Are the Signs and Symptoms of the Disease?

How Do Doctors Treat Cat Scratch Disease?




Cat scratch disease is an infectious illness that can cause flulike symptoms and swelling of lymph nodes*. It is caused by bacteria carried in cat saliva. The bacteria usually enter the body from a cat scratch or a bite that breaks the skin.

(LIMF) nodes are small, bean-shaped masses of tissue that contain immune system cells that fight harmful microorganisms. Lymph nodes may swell during infections.


for searching the Internet and other reference sources

Bartonella henselae bacteria

Illnesses associated with cats

Parinaud oculoglandular syndrome

What Is Cat Scratch Disease?

Cat scratch disease (also called cat scratch fever) is caused by the bacterium Bartonella henselae (bar-tuh-NEH-luh HEN-suh-lay), which is found in the saliva of cats and kittens all over the world. About 3 to 10 days after a person is bitten or scratched by a cat, a blister or small bump may develop. This is called an inoculation (ih-nah-kyoo-LAY-shun) lesion, which means that it appears at the site where germs entered the body. Usually about 2 weeks later, there is inflammation of nearby lymph nodes. If the scratch or bite is on the arm, the lymph nodes on the arm or in the armpit will become swollen. Swelling also can develop in the lymph nodes in the neck or groin, depending on the site of the scratch or bite.

Who Gets Cat Scratch Disease?

People of any age can get the disease, but most cases occur in children and teens. It is estimated that there are about 24,000 cases of cat scratch disease each year in the United States. Members of the same household can become ill if they are scratched or bitten by the same infected cat. Cat scratch disease affects 9 of every 100,000 persons each year worldwide. People can get the disease only from infected cats and kittens. It cannot be transmitted from person to person, but it can spread among cats. It is thought that cats and kittens can become infected with Bartonella henselae from fleas.

What Are the Signs and Symptoms of the Disease?

The most common symptoms of cat scratch disease are a bite or scratch that does not heal normally; painful or swollen glands (lymph nodes), especially in the armpit or near the inside of the elbow; fever; headache; fatigue; joint pain; and sometimes a rash. Less common symptoms are weight loss, sore throat, and draining lymph nodes. If a person is suspected of having cat scratch disease, the doctor will ask about any recent contact with a cat and will look for signs of a cat scratch or bite, swollen lymph nodes, or an inoculation lesion. In some cases, a person with cat scratch disease does not recall having had contact with a cat. Blood tests can rule out other causes of swollen nodes and check for the presence of antibodies* to the bacteria that cause the disease. In some cases, a doctor will use a needle to take a sample (a piece of tissue) from a swollen lymph node for examination under a microscope.

(AN-tih-bah-deez) are protein molecules produced by the bodys immune system to help fight specific infections caused by microorganisms, such as bacteria and viruses.

How Do Doctors Treat Cat Scratch Disease?

Antibiotics may be prescribed for cat scratch disease, but some doctors advise taking these medications only in severe cases. Most people eventually get well without treatment. If the patient is otherwise healthy, rest and over-the-counter medicines, such as acetaminophen (uh-see-teh-MIH-noh-fen), to relieve pain and fever are all that are needed while waiting for the disease to run its course. If a lymph node becomes very swollen and painful, the doctor may decide to drain it. Treatment with antibiotics often is recommended for patients who have weakened immune systems as the result of other illnesses. The symptoms in most patients usually resolve after several weeks of treatment with antibiotics and within 3 months without antibiotic treatment. Swollen lymph nodes may take several months to return to normal size. Most people recover completely from the illness. After an episode of cat scratch disease, people are usually immune to it, meaning that they cannot get the disease again.


Generally, cat scratch disease is not serious in people who are healthy. But people with weak immune systems, such as those with human immunodeficiency virus* (HIV) infection or poorly controlled diabetes* and those receiving chemotherapy for cancer, have a greater risk of complications and need to be watched closely by their health care providers. These complications include hepatitis*, osteomyelitis*, encephalitis*, and retinitis*. Sometimes cat scratch disease can appear in the form of Parinaud oculoglandular syndrome (PAH-rih-nod ok-yoo-lo-GLAN-dyoo-ler SIN-drome). In this condition, a small sore and inflammation develop in the membrane lining the inner eyelid, called the conjunctiva (kon-jung-TIE-vuh), accompanied by swollen lymph nodes around the ear. Rubbing ones eyes after handling an infected cat can transmit the infection to the conjunctiva, because the bacteria can be present on the cats coat wherever it licks itself.

*human immunodeficiency
(HYOO-mun ih-myoo-no-dih-FIH-shen-see) virus , or HIV, is the virus that causes AIDS (acquired immunodeficiency syndrome), an infection that severely weakens the immune system.
(dye-uh-BEE-teez) is a condition in which the bodys pancreas does not produce enough insulin or the body cannot use the insulin it makes effectively, resulting in increased levels of sugar in the blood. This can lead to increased urination, dehydration, weight loss, weakness, and a number of other symptoms and complications related to chemical imbalances within the body.
(heh-puh-TIE-tis) is an inflammation of the liver. Hepatitis can be caused by viruses, bacteria, and a number of other noninfectious medical conditions.
(ah-stee-o-my-uh-LYE-tis) is a bone infection that is usually caused by bacteria. It can involve any bone in the body, but it most commonly affects the long bones in the arms and legs.
(en-seh-fuh-LYE-tis) is an inflammation of the brain, usually caused by a viral infection.
(reh-tin-EYE-tis) is an inflammation of the retina, the nerve-rich membrane at the back of the eye on which visual images form.


About 30 percent of American households have pet cats. Keeping cats indoors and free of fleas may help prevent them from contracting the infection. It is a good idea to avoid stray or unfamiliar cats and not to provoke any cat or kitten to the point that it scratches or bites. Thoroughly cleaning any wounds inflicted by a cat may help prevent infection.

See also


Hepatitis, Infectious

The Nature of Germs and Infection






American Academy of Family Physicians, 11400 Tomahawk Creek Parkway, Leawood, KS 66211-2672. The American Academy of Family Physicians posts information about cat scratch disease at its website.

Telephone 800-274-2237

U.S. National Library of Medicine, 8600 Rockville Pike, Bethesda, MD 20894. The National Library of Medicine has a website packed with information on diseases (including cat scratch disease) and drugs, consumer resources, dictionaries and encyclopedias of medical terms, and directories of doctors and helpful organizations.

Telephone 888-346-3656

Website KidsHealth is a website created by the medical experts of the Nemours Foundation and is devoted to issues of childrens health. It contains articles on a variety of health topics, including cat scratch disease.

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