Cat scratch disease.
Cat scratch disease is a common infection, particularly in children, that usually presents as tender, swollen lymph nodes. The bacterium Bartonella henselae causes the disease, which is carried by different animals, mostly by cats, and is transmitted to humans through contaminated saliva by bites or clawing. Kittens transmit the disease more often than adult cats, possibly because of their tendency to be more playful with humans and consequently scratch more.
Cat fleas are responsible for the horizontal transmission of the disease from cat to cat, and on occasion, fleas or ticks may transmit the disease to humans. Studies show that about 40% of cats harbor this organism and can transmit the disease. Cats are usually asymptomatic and do not require any treatment.
There are approximately 22,000 new cases of cat scratch disease per year in the United States. Families with cats, and particularly kittens, in their households should be aware of this disease that affects mostly children.
The majority of patients (85-90%) are children or teenagers who develop swollen lymph nodes after contact with a kitten or cat. A primary skin lesion starts at the contact site as a blister. A small number of patients do not recall contact with cats or having skin lesions. Tender, swollen lymph nodes develop in the proximity of the bite or scratch approximately 1-2 weeks after the contact. A few patients develop low-grade fever, headache, malaise and rash. Occasionally muscle or joint aches can occur as well. Swollen lymph nodes can persist for a few months.
There are only a few cases that present with severe manifestations like enlargement of liver and spleen, prolonged fever, eye manifestations or seizures. Some of these cases can occur in patients with normal immunity. Children who have been treated with chemotherapy or suffer from abnormalities of the immune system are at high risk of developing severe forms of cat scratch disease and should avoid close contacts with kittens.
Diagnosis is usually made by clinical findings and history of exposure to kittens or cats. There are serologic tests that can be done by checking the blood of patients, but they are limited; a very high level of antibodies found in blood is suggestive of the disease. Generally, a positive antibody test does not mean that disease is active. The test can be positive in people who were exposed to this bacteria, usually, cat owners.
Cat scratch disease should be included in the differential diagnosis of fever of unknown origin and any syndrome that causes swollen lymph nodes that can be of other infectious causes or even leukemia or lymphoma in children.
There are other diseases associated with pets, frequently cats. Cellulitis is a very common disease that causes skin and soft tissue inflammation within 24-48 hours after a bite or a scratch and surrounds the area of trauma. This manifestation is very different from the small blister that can be seen at the beginning of cat scratch disease. In cellulitis, the skin is warm, red and tender to touch around the bite or scratch and requires immediate medical attention and antibiotic treatment.
Most cases of cat scratch disease resolve on their own. Studies show that antibiotic treatment is not required in these cases. If lymph nodes are painful, then an anti-inflammatory medicine like ibuprofen can be used in small doses when needed. If an antibiotic is chosen to be given by the physician, then azithromycin for five days has been shown in one small study to speed recovery. Up to 14% of patients have more severe manifestations and these patients need treatment with antibiotics. These patients should be treated with antibiotics in consultation with an infectious disease specialist.
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Dr. Voichita Ianas, MD, is an infectious diseases physician in Phoenix, Arizona and recent graduate of the University of Arizona infectious diseases fellowship. She has written about cat scratch disease along with Dr. Klotz. Dr. Klotz is Chief of the Section of Infectious Diseases at the University of Arizona, Tucson, AZ.
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|Author:||Ianas, Voichita; Klotz, Stephen A.|
|Publication:||Pediatrics for Parents|
|Date:||Mar 1, 2011|
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