Cat scratch disease (CSD) is a bacterial disease caused by Bartonella henselae. Most people with CSD have been bitten or scratched by a cat and developed a mild infection at the point of injury. Lymph nodes, especially those around the head, neck, and upper limbs, become swollen. Additionally, a person with CSD may experience fever, headache, fatigue, and a poor appetite. Rare complications of B. henselae infection are bacillary angiomatosis and Parinaud's oculolandular syndrome.

Causes

Most people get CSD from cat bites and scratches. Kittens are more likely to be infected and to pass the bacterium to people. About 40% of cats carry B. henselae at some time in their lives. Cats that carry B. henselae do not show any signs of illness; therefore, you cannot tell which cats can spread the disease to you. People with immunocompromised conditions, such as those undergoing immunosuppressive treatments for cancer, organ transplant patients, and people with HIV/AIDS, are more likely than others to have complications of CSD. Although B. henselae has been found in fleas, so far there is no evidence that a bite from an infected flea can give you CSD.

Symptoms

• A crusting sore or blister that develops over the site of a cat scratch or bite

• Swollen, painful lymph nodes

• Low-grade fever

• Flu-like symptoms such as weakness, nausea, chills, loss of appetite, and headache.

• If you do not start to get well within in a few days, you may develop complications such as a very high fever or pneumonia. Severe cases have caused infections of the brain (encephalitis), hepatitis, and even death.

Diagnosis

Your doctor will ask about your symptoms and medical history, and perform a physical exam. If you remember that you were bitten or scratched by a cat, your doctor will probably be able to diagnose the disease based on the fact that you were bitten or scratched, then got painful, swollen lymph nodes. Tests may include:

• A blood test, especially if the diagnosis is not clear from the exam and medical history alone.

Treatment

Talk with your doctor about the best treatment plan for you. Treatment options include:

• Rest and non-prescription pain relievers, such as acetaminophen.

• Lymph node drainage – If a lymph node is very swollen or very painful, your doctor may drain it to help it heal and to relieve pain. To do this, your doctor will put a hypodermic needle into the swollen node. Fluid inside the node will then drain out through the needle.

• Antibiotics – Cat-scratch fever usually clears up without treatment. If lymph nodes stay painful and swollen for more than two or three weeks, or if you get very ill, you may need antibiotic treatment. Antibiotics may also be prescribed for those with HIV infection or other immunocompromising diseases.

Prevention

• Avoid "rough play" with cats, especially kittens. This includes any activity that may lead to cat scratches and bites.
• Wash cat bites and scratches immediately and thoroughly with running water and soap.
• Do not allow cats to lick open wounds that you may have.
• Control fleas.
• If you develop an infection (with pus and pronounced swelling) where you were scratched or bitten by a cat or develop symptoms, including fever, headache, swollen lymph nodes, and fatigue, contact your physician.

RESOURCES:

Cat Scratch Disease
National Center for Infectious Diseases
http://www.cdc.gov

Winn Feline Foundation
http://www.winnfelinehealth.org

CANADIAN RESOURCES:

BC Health Guide
British Columbia Ministry of Health
http://www.bchealthguide.org

Cat Scratch Fever
Animal Healthcare Information and Advice from Canadian Veterinarians (animalhealthcare.ca)
http://www.animalhealthcare.ca

References:

CDC

Chomel BB. Cat-scratch disease. Rev Sci Tech. 2000;19(1):136-50.

Conrad DA. Treatment of cat-scratch disease. Curr Opin Pediatr. 2001;13(1):56-9.

Lamps LW, Scott MA. Cat-scratch disease: historic, clinical, and pathologic perspectives. Am J Clin Pathol. 2004;121 Suppl:S71-80.

Windsor JJ. Cat-scratch disease: epidemiology, aetiology, and treatment. Br J Biomed Sci. 2001;58(2):101-10.