What is Cat Scratch Disease?
Cat scratch disease is a bacterial infection that typically
causes swelling of the lymph nodes. It usually results from the
, lick, or bite of a cat - more than 90% of people with the illness
have had some kind of contact with cats, often with kittens.
that causes cat scratch disease, and it's found in all parts of
the world. Cat scratch disease occurs more often in the fall and
winter. In the United States, about 22,000 cases are diagnosed
annually, most of them in people under the age of 21. This may be
because children are more likely to play with cats and be bitten or
Fleas spread the bacteria between cats, although currently there
is no evidence that fleas can transmit the disease to humans. Once
a cat is infected, the bacteria live in the animal's saliva.
does not make a cat sick, and kittens or cats may carry the
bacteria for months. Experts believe that almost half of all cats
infection at some time in their lives, and cats less than 1 year
old are more likely to be infected.
Signs and Symptoms
Most people with cat scratch disease remember being around a
cat, but often cannot recall receiving a scratch or a bite. A
blister or a small bump develops several days after the scratch or
bite and may be mistaken for a
. This blister or bump is called an inoculation lesion (a wound at
the site where the bacteria enter the body), and it is most
commonly found on the arms and hands, head, or scalp. These lesions
are generally not painful.
Usually within a couple of weeks of a scratch or bite, one or
more lymph nodes close to the area of the inoculation lesion will
swell and become tender. (Lymph nodes are round or oval-shaped
organs of the immune system that are often called glands.) For
example, if the inoculation lesion is on the arm, the lymph nodes
in the elbow or armpit will swell.
These swollen lymph nodes appear most often in the underarm or
neck areas, although if the inoculation lesion is on the leg, then
the nodes in the groin will be affected. They range in size from
about 1/2 inch to 2 inches in diameter and may be surrounded by a
larger area of swelling under the skin. The skin over these swollen
lymph nodes may become warm and red, and occasionally the lymph
nodes drain pus.
In most children and adolescents, swollen lymph nodes are the
main symptom of the disease, and the illness often is mild. About
one third of people with cat scratch disease have other general
symptoms. These include
(usually less than 101Âº Fahrenheit or 38.3Âº Celsius), fatigue, loss
of appetite, headache, rash, sore throat, and an overall ill
Atypical cases of cat scratch disease do occur, but they are
much less common. In such cases, a person may have infections of
the liver, spleen, bones, joints, or lungs, or a lingering high
fever without any other symptoms. Some people get an eye infection
known as Parinaud oculoglandular syndrome, with symptoms including:
a small sore on the conjunctiva (the membrane lining the eye or
inner eyelid), redness of the eye, and swollen lymph nodes in front
of the ear. Others may develop inflammation of the brain or
, although this is rare. All of these complications of cat scratch
disease usually resolve without any lasting illness.
Cat scratch disease is not contagious from person to person. The
bacteria are spread by the scratch or bite of an infected animal,
most often a kitten. They can also be transmitted if the
animal's saliva comes in contact with broken skin or an eye.
Sometimes multiple cases of the illness occur in the same family,
but these likely result from contact with the same infected
Having one episode of cat scratch disease usually makes people
immune for the rest of their lives.
If you're concerned about cat scratch disease, you do not
need to get rid of the
. The illness is relatively rare and usually mild, and a few steps
can go a long way toward limiting your child's chances of
contracting the disease.
Teaching kids to avoid stray or unfamiliar cats can reduce their
exposure to sources of the bacteria. To lower the risk of getting
the disease from a family pet or familiar cat, kids should avoid
rough play with any pets so they can avoid being scratched or
bitten. Have your family members
wash their hands
after handling or playing with a cat.
If your child is scratched by a pet, wash the injured area
thoroughly with soap and water. Keeping the house and your pet free
of fleas will reduce the risk that your cat could become infected
with the bacteria in the first place.
If you suspect that someone in your family has caught cat
scratch disease from your family pet, you don't need to worry
that the animal will have to be put to sleep. Talk with your
veterinarian about the problem.
It typically takes 3 to 10 days for a blister or small bump to
appear at the site of a scratch or bite. Lymph node swelling
usually begins about 1 to 4 weeks later.
The inoculation lesion where the bacteria entered the body
usually takes days to heal. The swollen lymph nodes typically
disappear within 2 to 4 months, although they occasionally last
Doctors usually diagnose cat scratch disease based on a
child's history of exposure to a cat or kitten and a physical
examination. During the exam, a doctor will look for signs of a cat
scratch or bite and swollen lymph nodes. In some cases, doctors use
laboratory tests to help make the diagnosis, including:
- skin tests, blood tests, and cultures to rule out other
causes of swollen lymph nodes
- a blood test that is positive for cat scratch disease
- a microscopic examination of a removed lymph node that shows
signs of cat scratch disease
Most cases of cat scratch disease resolve without any treatment
at all. Rarely, a swollen lymph node becomes so large and painful
that the doctor may recommend removing fluid from the node with a
needle and syringe. Antibiotics can be used to treat the disease.
If your doctor has prescribed antibiotics, give the medication to
your child on schedule for as many days as the doctor has
A child who has cat scratch disease does not need to be isolated
from other family members. Bed rest is not necessary, but it may
help if your child tires easily. If your child feels like playing,
encourage quiet play while being careful to avoid injuring swollen
lymph nodes. To ease the soreness of these nodes, try warm, moist
compresses or give your child nonprescription medicines like
acetaminophen or ibuprofen.
When to Call the Doctor
Call your doctor whenever your child has swollen or painful
lymph nodes in any area of the body, or if your child is ever
bitten by an animal. You should call if your child has been
bitten or scratched by a cat and the wound does not seem to be
healing, an area of redness around the wound keeps expanding for
several days, or your child develops a fever that lasts for a few
days after receiving the scratch or bite.
If your child has already been diagnosed with cat scratch
disease, call the doctor if your child has a high fever, has lots
of pain in a lymph node, seems very sick, or develops any new
Larissa Hirsch, MD
Date reviewed: July 2006
Note: All information is for educational purposes only. For specific medical advice,
diagnoses, and treatment, consult your doctor.
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