Cat Scratch Disease

What Is Cat Scratch Disease?

Cat Scratch Disease (CSD) is caused by the bite or scratch of a cat infected with Bartonella henselae. It is found in all parts of the world, but the infection occurs more often in the fall and winter. In the United States, about 22,000 cases of CSD are diagnosed annually. There is no evidence that fleas spread the disease from cats to humans. Bartonella henselae does not make a cat appear sick and the cat may carry the agent for months.

Routes of Infection

Humans become infected when a cat infected with B. henselae bites or scratches them. A blister or small bump often develops several days after the scratch or bite and generally is not painful. Lymph nodes close to the blister or bum begins to swell which then become warm and red. This then progresses to include fever, fatigue, loss of appetite, headache, rash, sore throat, and overall ill feeling.


CSD is not contagious, but people can become infected if an animal’s saliva comes in contact with broken skin or an eye. Having one episode of CSD usually makes people immune for the rest of their lives.


Washing your hands thoroughly with soap and water after handling cats will reduce the risk of acquiring CSD.