Cat-scratch disease is an infection with bartonella bacteria that is believed to be transmitted by cat scratches, cat bites, or flea bites.
CSD; Cat-scratch fever; Bartonellosis
Cat-scratch disease is caused by the bacteria Bartonella henselae. The disease is spread through contact with an infected cat (a bite or scratch) or exposure to cat fleas. It also can be spread through contact with cat saliva on broken skin or mucosal surfaces like those in the nose, mouth, and eyes.
A person who has had contact with an infected cat may show common symptoms, including:
- Bump (papule) or blister (pustule) at site of injury (usually the first sign)
- Fever (in some people)
- Lymph node swelling (lymphadenopathy) near the site of the scratch or bite
- Overall discomfort (malaise)
Less common symptoms may include:
- Loss of appetite
- Sore throat
- Weight loss
Exams and Tests
If you have swollen lymph nodes and a scratch or bite from a cat, your health care provider may suspect cat-scratch disease.
A physical examination may also reveal an enlarged spleen.
Sometimes, an infected lymph node may form a tunnel (fistula) through the skin and drain (leak fluid).
This disease is often not found because it is hard to diagnose. The Bartonella henselae immunofluorescence assay (IFA) blood test is an accurate way to detect the infection caused by these bacteria. The results of this test must be considered along with other information from your medical history, lab tests, or biopsy.
A lymph node biopsy may also be done to look for other causes of swollen glands.
Generally, cat-scratch disease is not serious. Medical treatment may not be needed. In some cases, treatment with antibiotics such as azithromycin can be helpful. Other antibiotics may be used, including clarithromycin, rifampin, trimethoprim-sulfamethoxazole, or ciprofloxacin.
In people with HIV/AIDS and others, who have a weakened immune system, cat-scratch disease is more serious. Treatment with antibiotics is recommended.
People who have a healthy immune system should recover fully without treatment. In people with a weakened immune system, treatment with antibiotics usually leads to recovery.
People whose immune systems are weakened may develop complications such as:
- Encephalopathy (loss of brain function)
- Neuroretinitis (inflammation of the retina and optic nerve of the eye)
- Osteomyelitis (bone infection)
- Parinaud syndrome (red, irritated, and painful eye)
When to Contact a Medical Professional
Call your provider if you have enlarged lymph nodes and you have been exposed to a cat.
To prevent cat-scratch disease:
- Wash your hands thoroughly with soap and water after playing with your cat. Especially wash any bites or scratches.
- Play gently with cats so they don't scratch and bite.
- Don't allow a cat to lick your skin, eyes, mouth, or open wounds or scratches.
- Use flea control measures to lower the risk your cat develops the disease.
- Don't touch feral cats.
Gandhi TN, Slater LN, Welch DF, Koehler JE. Bartonella, including cat-scratch disease. In: Bennett JE, Dolin R, Blaser MJ, eds. Mandell, Douglas, and Bennett's Principles and Practice of Infectious Diseases, Updated Edition. 8th ed. Philadelphia, PA: Elsevier Saunders; 2015:chap 236.
Patterson JW. Bacterial and rickettsial infections. In: Patterson JW, ed. Weedon's Skin Pathology. 4th ed. Philadelphia, PA: Elsevier Churchill Livingstone; 2016:chap 23.
Reviewed By: Jatin M. Vyas, MD, PhD, Assistant Professor in Medicine, Harvard Medical School; Assistant in Medicine, Division of Infectious Disease, Department of Medicine, Massachusetts General Hospital, Boston, MA. Also reviewed by David Zieve, MD, MHA, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team.