Cat scratch disease

Cat scratch disease (CSD) or cat scratch fever is a bacterial infection spread by cats. 

It may occur when an infected cat licks an open wound, or bites or scratches you hard enough to break the skin. Roughly three to 14 days after the skin is broken, the scratch site may become mildly infected. The infected area is typically swollen and red with round, raised lesions and can have pus. 

CSD is caused by bacteria called Bartonella henselae. While it is common in cats, most cats with the infection do not become ill. Kittens are more likely to pass on the bacteria than fully grown adults.

CSD is usually not a serious illness in people with normal immune function, but if left untreated, it can lead to complications. This can affect the brain, eye, heart and other internal organs. 

These rare complications, which may require intensive treatment, are more likely to occur in children younger than five years and people with weak immune systems, such as those of HIV/AIDS patients.

Complications may include:

  • Encephalopathy (abnormal brain function)
  • Neuroretinitis (inflammation of the optic nerve)
  • Osteomyelitis (bone infection)
  • Parinaud’s syndrome (inability to move the eyes up or down)

What are its symptoms?

CSD signs and symptoms may include:

Less common symptoms include weight loss and a sore throat.

How is it diagnosed? 

If your doctor suspects CSD, he/she will perform a physical examination to see if you have an enlarged spleen (the organ above your stomach). 

Diagnosis is difficult from the symptoms alone. Your doctor can make an accurate diagnosis, however, by performing an indirect fluorescent antibody (IFA) blood test to see if the Bartonella henselae bacteria are present in your body. 

In this test, antibodies that are labelled with dye will attach to existing antibodies of Bartonella (also known as anti-antibodies) and show up during the test.

A lymph node biopsy may also be done to look for other causes of swollen glands.

What are your treatment options? 

Treatment of cat scratch disease is straightforward as it is not usually serious. In most people, it clears up without treatment. Over-the-counter pain relievers such as aspirin, ibuprofen and naproxen, or a heat compress, can ease pain and discomfort.

Antibiotics may be prescribed however, when infected lymph nodes remain painful and swollen for more than a few months. Antibiotics may also help if you have a fever, or if the infection is in your bones, liver or another organ.

Your doctor may drain a lymph node if it is very large or painful.

Can it be prevented? 

Prevention of cat scratch disease begins with avoiding rough contact with cats. If you have a cat, avoid play that could lead to you being bitten or scratched. Also remember to wash your hands after playing with your cat. 

Keep your cat indoors and administer anti-flea medication to reduce the risk of your cat contracting Bartonella henselae. 

The accuracy of this information was checked and approved by physician Dr Thomas Blake in May 2016