A bump (papule) or blister (pustule) at the site of injury is the first sign of cat scratch disease. It may take anywhere from three to 10 days before this sore appears, at which point it often is mistaken for an insect bite. Sores most often appear on the arms, hands, neck, head or scalp and are not usually painful. Sores related to cat scratch disease may take several days or months to heal. They do not typically leave a scar.

About two to three weeks after infection, the patient will begin to experience swelling of the lymph nodes near the infection site. For example, a patient bitten on the arm will experience swelling of the lymph nodes in the elbow or armpit. Redness, warmth and draining pus may also be associated with the swollen lymph node. This swelling may continue for months or years and may spread to other lymph nodes in the drainage route connected to the lymph nodes at the injury site. Lymph nodes of the upper arm are most often affected, followed by the head, neck and groin.

About one-third of patients will develop a fever related to cat scratch disease, followed by fatigue, headache and a feeling of overall discomfort. Less frequently, patients may experience loss of appetite (anorexia) and weight loss, an enlarged spleen and a sore throat.

In most cases, cat scratch disease resolves on its own and does not require treatment. However, rare cases should receive medical attention. In some cases, the swollen lymph nodes may form a fistula (an abnormal passage) to the skin. Infection can sometimes spread to the liver, spleen, bones or lungs. In rare cases, patients may also develop an eye infection known as parinaud oculoglandular syndrome. This is characterized by a small sore on the conjunctiva (the membrane lining the eye and inner eyelid), redness of the eye and swollen lymph nodes in front of the ear. Inflammation of the brain may also trigger seizures.

Another rare complication of Bartonella henselae infection is bacillary angiomatosis. This condition is characterized by the appearance of purple or bright red patches on the skin. Most often seen in HIV patients, the condition can lead to disorders of the liver and spleen.

Anyone experiencing symptoms of these complications is urged to seek medical attention.

Other symptoms that indicate a need for medical care include:

• Cat scratches or bites that do not heal
  
  
• Redness around a cat scratch or bite that increases for more than two days
  
  
• Fever that lasts for several days following a bite
  
  
• Painful and swollen lymph nodes for more than two weeks
  
  
• Bone or joint pain
  
  
• Abdominal pain
  
  
• Fatigue that lasts for more than two weeks