Cat scratch disease is an infection transmitted to people from cats, although other animal species have been involved.  It is most common in children but can affect people of all ages.  The causative organism (carried by fleas) gains entry through a cat scratch or bite although some affected people have no evident wounds.  Nearly all infected people have had some recent contact with a cat. 

Cat scratch disease typically causes enlargement of a lymph node or several lymph nodes in the area of the wound.  Other signs may include fever, headache, sore throat, and lack of appetite.  Signs may last for weeks or months, and usually are self-limiting (disappear without treatment).

Cat scratch disease is diagnosed by the person's history, clinical signs, and laboratory tests.  Lymph nosde enlargement is a common sign.  Most affected people have had recent contact with a cat or kitten, and have also sustained a scratch or bite wound.  Blood cultures, serologic tests, and a skin test can also be used in diagnosis.