Cat-Scratch Disease

An enlarged lymph node in the armpit region of a person with cat-scratch disease, and wounds from a cat scratch on the hand.

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.

How cats and people become infected

Kitten playing with a person's fingers.

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

People

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.

Cats

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.

People

Do:

A cat's paw with long sharp nails.

• 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.

Do not:

• 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.

Cats

Control fleas

Cats scratching at fleas

• Keep your cat's nails trimmed.
• Apply a flea product (topical or oral medication) approved by your veterinarian once a month.
  • BEWARE: Over-the-counter flea products may not be safe for cats. 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

A veterinarian examines a cat.

People

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.

Cats

Talk to your veterinarian about testing and treatments for your cat. Your veterinarian can tell you whether your cat requires testing or treatment.

CDC's Bartonella page

Cat-scratch disease in children—Texas, September 2000–August 2001. Morbidity and Mortality Weekly Report. 2002 Mar;51(10):212-214.

Other Publications:

Regnery R, Tappero J. Unraveling mysteries associated with cat-scratch disease, bacillary angiomatosis, and related syndromes. Emerging Infectious Diseases. 1995 Jan-Mar;1(1):16-21.

Epidemiologic notes and reports encephalitis associated with cat scratch disease — Broward and Palm Beach Counties, Florida, 1994. Morbidity and Mortality Weekly Report. 1994 Dec;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.