Cat scratch disease is a bacterial infection that a person can get after being scratched, licked, or bitten by a cat or kitten.
In the United States, most cases happen in the fall and winter and usually affect kids, probably because they're more likely to play with cats and be bitten or scratched.
Bartonella henselae, the bacteria that cause this disease, live in infected cats' saliva but don't make the animals sick. In fact, kittens or cats may carry the bacteria for months. Fleas spread the bacteria between cats.
Signs & Symptoms
The first sign of this infection is a blister or a small bump that develops several days after the scratch or bite and may resemble a bug bite. This blister or bump is called an inoculation lesion (a wound at the site where the bacteria enter the body). Lesions are most commonly found on the arms and hands, head, or scalp and usually are not painful.
Within a couple of weeks of a scratch or bite, one or more lymph nodes close to the area of the inoculation lesion will swell and become tender. (Lymph nodes are round or oval-shaped organs of the immune system that are often called glands.) For example, if the inoculation lesion is on the arm, the lymph nodes in the elbow or armpit will swell.
These swollen lymph nodes appear most often in the underarm or neck areas, although if the inoculation lesion is on the leg, the nodes in the groin will be affected. They range in size from about ½ inch to 2 inches in diameter and may be surrounded by a larger area of swelling under the skin. The skin over these swollen lymph nodes can become warm and red.
In most kids, swollen lymph nodes are the main symptom of the disease, and the illness often is mild. If kids have other general symptoms, they might include fever (usually less than 101°F or 38.3°C ), fatigue, loss of appetite, headache, rash, sore throat, and an overall ill feeling.
The swollen lymph nodes usually disappear within 2 to 4 months, although sometimes can last much longer. In rare cases, a person might develop other symptoms, including infections of the liver, spleen, bones, joints, or lungs, or a lingering high fever without other symptoms.