Cat-Scratch Disease

Cat-scratch disease is an infection caused by bacteria (germs) carried in cat saliva. The bacteria can be passed from a cat to a human. Doctors and researchers think cats may get the bacteria from fleas, although this hasn't been proved.

You can get cat-scratch disease from a cat bite or cat scratch. You can get the infection after a cat scratches you if the cat's paws have the bacteria on them. (A cat can get the bacteria on its paws when it licks itself.) With a cat bite, the cat can pass the bacteria to you in its saliva. You can also get the bacteria in your eyes if you pet a cat that has the bacteria on its fur and then rub your eyes. Many people who get cat-scratch disease do not remember being scratched or bitten by a cat.

Cat-scratch disease is not a severe illness in people who are healthy. But it can be a problem in people with weak immune systems. People with weak immune systems include those who are receiving chemotherapy for cancer, those who have diabetes or those who have acquired immunodeficiency syndrome (AIDS).

A sore may develop where a cat has bitten or scratched you. The sore might not happen right away. It may take 3 to 10 days for the sore to appear after the bite or scratch.

The sore may take a long time to heal. An infection of the lymph nodes (also called lymph glands) also develops, most often in the glands that are near the place where you got the cat scratch or cat bite. For example, if the infection is from a cat scratch on your arm, the glands in your armpit may become tender and swollen. The lymph nodes may swell to an inch or more in size.

If you remember that you were bitten or scratched by a cat, your doctor will probably be able to diagnose the illness based on the fact that you were bitten or scratched and then got painful, swollen lymph nodes. When the diagnosis is not clear, a blood test may help your doctor make the diagnosis.

In most people, cat-scratch disease clears up without treatment. However, antibiotics (medicines that kill bacteria) may be needed when infected lymph nodes stay painful and swollen for more than 2 or 3 months. Antibiotics may also help if you have a fever for a long time or if the infection is in your bones, liver or another organ.

If a lymph node is very large or painful, your doctor may drain it to help relieve the pain. The lymph node is drained by putting a needle through normal skin off to the side of the node and moving the needle to the swollen node. The needle is then inserted into the node and the fluid in the node is drained out.

Avoiding cats is the simplest way to prevent the disease, but it is not usually necessary to get rid of your cat. Try to avoid any situation where you might be bitten or scratched by a cat. Do not tease or provoke a cat. Most scratches and bites come from cats that are provoked. Washing your hands carefully after handling your cat is another way to prevent the infection. Getting rid of fleas on your cat will also keep you and your family members from catching the infection.

Cats only seem to be able to transmit this infection for a few weeks. Young cats seem to be more likely to carry the bacteria than older cats. Households with kittens have higher rates of infection. If the kittens have fleas, the infection rate is even higher.

Cats require no treatment. The bacteria doesn't cause cats to get sick. They merely carry the bacteria that causes cat-scratch disease in people.