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.

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.

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.

Complications

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 (konjung-TIE-vuh), accompanied by swollen lymph nodes around the ear. Rubbing one's eyes after handling an infected cat can transmit the infection to the conjunctiva, because the bacteria can be present on the cat's coat wherever it licks itself.

Prevention

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

It was not until the 1980s that Bartonella bacteria were identified as the cause of cat scratch disease. Infection does not appear to make cats ill, making it easier for the disease to spread from cat to cat (through fleas) and then to people.

George Zebrowski