What is cat scratch disease?

Cat scratches and bites can cause cat scratch disease, a bacterial infection carried in cat saliva. Research suggests a cat may get these bacteria from fleas or their droppings. Kittens younger than 1 year of age are more likely to have the bacteria in their saliva and also are more likely to scratch or bite. This increases the risk of infection from younger cats.

What causes cat scratch disease?

Cat scratch disease is caused by a bacterium carried in cat saliva. The bacteria are passed from an infected cat to a human after the cat licks an open wound or bites or scratches human skin hard enough to break the surface of the skin.

Who is at risk for cat scratch disease?

Factors that can increase your risk for getting cat scratch disease include:

• Being around cats on a routine basis, especially kittens that are more playful and apt to accidentally scratch you

• Not cleaning scratches or bites from a cat as soon as you get them

• Allowing a cat to lick any open wounds that you have

• Being around a flea infestation

What are the symptoms of cat scratch disease?

These are the most common symptoms of cat scratch disease:

• A cat bite or scratch that becomes reddened or swollen within a few days and does not heal or worsens over time

• Painful or swollen glands, especially under the arms (if scratched on the arm or hand) or in the groin (if scratched on the foot or leg)

• Flu-like symptoms, including headache, decreased appetite, fatigue, joint pain, or fever

• Scab or blister filled with pus (pustule) at the scratch site

The symptoms of cat scratch disease may look like other conditions or medical problems. Always see your healthcare provider for a diagnosis.

How is cat scratch disease diagnosed?

Diagnosis is based on a complete history, including a history of being scratched by a cat or kitten, a physical exam, and sometimes blood tests or testing a sample from the lymph node.

How is cat scratch disease treated?

Treatment will depend on your symptoms, age, and general health. It will also depend on how severe the condition is.

Treatment may include:

• Antibiotics to treat the infection

• Care for the symptoms that result from the infection. In most cases, no antibiotics are needed, and the infection will clear on its own.

What are possible complications of cat scratch disease?

Most healthy people don't have complications from cat scratch disease. But people whose immune systems are weak (such as those who have HIV/AIDS, are receiving chemotherapy, or have diabetes) can have complications such as:

• Bacillary angiomatosis. This is a skin disorder that causes red, elevated lesions surrounded by a scaly ring. It may become a more widespread disorder that involves internal organs. 

• Parinaud oculoglandular syndrome. This condition causes a red, irritated, and painful eye similar to conjunctivitis (pink eye). It also may cause a fever and swollen lymph nodes in front of the ear on the same side.

• Endocarditis. This is a serious condition caused by an infection of the inner lining of the heart.

Can cat scratch disease be prevented?

You can prevent this disease by trying not to be scratched or bitten by cats or kittens. If scratched or bitten, wash the area right away with soap and water. Don't allow cats to lick wounds you may have.

When should I call my healthcare provider?

Call your healthcare provider if a cat scratch or bite becomes red or swollen and you develop flu-like symptoms, such as headache, decreased appetite, fatigue, joint pain, or fever.

Key points about cat scratch disease

• Cat scratch disease is an infection caused by a bacterium in cat saliva.

• The disease causes redness and swelling at the site of a cat scratch or bite and flu-like symptoms.

• If you are scratched or bitten by a cat or kitten, it's important to promptly wash the area with soap and water right away.

• Cat scratch disease can be treated by antibiotics.

Next steps

Tips to help you get the most from a visit to your healthcare provider:

• Know the reason for your visit and what you want to happen.

• Before your visit, write down questions you want answered.

• Bring someone with you to help you ask questions and remember what your provider tells you.

• At the visit, write down the name of a new diagnosis and any new medicines, treatments, or tests. Also write down any new instructions your provider gives you.

• Know why a new medicine or treatment is prescribed and how it will help you. Also know what the side effects are and when they should be reported.

• Ask if your condition can be treated in other ways.

• Know why a test or procedure is recommended and what the results could mean.

• Know what to expect if you do not take the medicine or have the test or procedure.

• If you have a follow-up appointment, write down the date, time, and purpose for that visit.

• Know how you can contact your provider if you have questions.