Cat scratch disease facts*
*Cat scratch disease facts by John P. Cunha, DO, FACOEP
- Cat scratch disease (CSD) is a bacterial disease caused by Bartonella henselae.
- It is often caused by a bite or scratch from a cat. Kittens are more likely to pass on the bacteria. Cats who carry B. henselae do not show any signs of illness, so you cannot tell which cats could spread the disease to you.
- Symptoms and signs of cat scratch disease include a bump or blister at the site of the scratch followed by
- People with suppressed immune systems, such as people undergoing chemotherapy, organ transplant patients, and people with HIV/AIDS, are more likely to have complications of CSD.
- Diagnosis of cat scratch disease is made by a history of a wound caused by a cat, physical exam showing signs of lymph node swelling, indirect fluorescence assay (IFA), and enzyme-linked immunoassay (ELISA) blood testing, and possibly lymph node biopsy.
- Treatment for cat scratch disease includes antibiotics such as azithromycin (Zithromax), clarithromycin (Biaxin), rifampin (Rifadin), trimethoprim-sulfamethoxazole (Bactrim), and ciprofloxacin (Cipro).
- To reduce your risk of getting CSD, avoid rough play with cats and kittens, wash cat bites and scratches thoroughly, don't allow cats to lick any open wounds you have, and contact your physician if you develop any symptoms or signs following a cat bite or scratch.
What is cat scratch disease?
Cat-scratch disease (CSD) is a bacterial infection spread by cats. The disease spreads when an infected cat licks a person's open wound, or bites or scratches a person hard enough to break the surface of the skin. About three to 14 days after the skin is broken, a mild infection can occur at the site of the scratch or bite. The infected area may appear swollen and red with round, raised lesions and can have pus. The infection can feel warm or painful. A person with CSD may also have a fever, headache, poor appetite, and exhaustion. Later, the person's lymph nodes closest to the original scratch or bite can become swollen, tender, or painful.
Wash cat bites and scratches well with soap and running water. Do not allow cats to lick your wounds. Contact your doctor if you develop any symptoms of cat-scratch disease or infection.
CSD is caused by a bacterium called Bartonella henselae. About 40% of cats carry B. henselae at some time in their lives, although most cats with this infection show NO signs of illness. Kittens younger than 1 year are more likely to have B. henselae infection and to spread the germ to people. Kittens are also more likely to scratch and bite while they play and learn how to attack prey.
Quick GuideSymptoms of Mono: Infectious Mononucleosis Treatment
Cat Scratch Disease Symptoms & Signs
Cat scratch disease, also known as catscratch disease, cat scratch fever, or subacute regional lymphadenitis, produces symptoms due to bacterial infection of the lymph nodes with bacteria known as Bartonella henselae. Most patients have a history of exposure to cats, and the disease begins with a reddish brown nodule (bump) at the site of infection. There is typically no pain or tenderness. Over the next weeks, there is enlargement of the lymph nodes that may be accompanied by tenderness.
How cats and people become infected
Cats can get infected with B. henselae from flea bites and flea dirt (droppings) getting into their wounds. By scratching and biting at the fleas, cats pick up the infected flea dirt under their nails and between their teeth. Cats can also become infected by fighting with other cats that are infected. The germ spreads to people when infected cats bite or scratch a person hard enough to break their skin. The germ can also spread when infected cats lick at wounds or scabs that you may have.
Serious but rare complications
Although rare, CSD can cause people to have serious complications. CSD can affect the brain, eyes, heart, or other internal organs. These rare complications, which may require intensive treatment, are more likely to occur in children younger than 5 years and people with weakened immune systems.
Most cats with B. henselae infection show NO signs of illness, but on rare occasions this disease can cause inflammation of the heart -- making cats very sick with labored breathing. B. henselae infection may also develop in the mouth, urinary system, or eyes. Your veterinarian may find that some of your cat's other organs may be inflamed.
Available tests and treatments
Talk to your doctor about testing and treatments for CSD. People are only tested for CSD when the disease is severe and the doctor suspects CSD based on the patient's symptoms. CSD is typically not treated in otherwise healthy people.
Talk to your veterinarian about testing and treatments for your cat. Your veterinarian can tell you whether your cat requires testing or treatment.
- Wash cat bites and scratches right away with soap and running water.
- Wash your hands with soap and running water after playing with your cat, especially if you live with young children or people with weakened immune systems.
- Since cats less than one year of age are more likely to have CSD and spread it to people, persons with a weakened immune system should adopt cats older than one year of age.
- Play rough with your pets because they may scratch and bite.
- Allow cats to lick your open wounds.
- Pet or touch stray or feral cats.
- Keep your cat's nails trimmed.
- Apply a flea product (topical or oral medication) approved by your veterinarian once a month.
- Check with your veterinarian before applying ANY flea product to make sure it is safe for your cat and your family. Check for fleas by using a flea comb on your cat to inspect for flea dirt.
- Control fleas in your home by
- Vacuuming frequently
- Contacting a pest-control agent if necessary
Protect your cat's health
- Schedule routine veterinary health check-ups.
- Keep cats indoors to
- Decrease their contact with fleas
- Prevent them from fighting with stray or potentially infected animals
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Epidemiologic Notes and Reports Encephalitis Associated with Cat Scratch Disease - Broward and Palm Beach Counties, Florida, 1994. Morbidity and Mortality Weekly Report. December 16, 1994 / 43(49);909,915-916.
Mofenson LM, Brady MT, Danner SP, Dominguez KL, Hazra R, Handelsman E, et al. Guidelines for the prevention and treatment of opportunistic infections among HIV-exposed and HIV-infected children. Morbidity and Mortality Weekly Report. 2009 Sept;58(RR11):1-166.
Last updated Apr. 30, 2014
Centers for Disease Control and Prevention
Reviewed on 9/30/2016