Cat-scratch disease is an uncommon infection that typically results from a
cat's scratch or bite. Most
sufferers experience only moderate discomfort and find that their
symptoms clear up without any lasting harm after a few weeks or months.
Professional medical treatment is rarely needed.
Cat-scratch disease (also called cat-scratch fever) is caused by the
bacterium, which is found in cats around the world and is transmitted
from cat to cat by fleas. Researchers have discovered that large numbers
of North American cats carry antibodies for the disease (meaning that the
cats have been infected at some point in their lives). Some parts of North
America have much higher rates of cat infection than others, however.
is uncommon or absent in cold climates, which fleas have difficulty
tolerating, but prevalent in warm, humid places such as Memphis,
Tennessee, where antibodies were found in 71 percent of the cats tested.
The bacterium, which remains in a cat's bloodstream for several
months after infection, seems to be harmless to most cats, and normally an
infected cat will not display any symptoms. Kittens (cats younger than one
year old) are more likely than adult cats to be carrying the infection.
can infect people who are scratched or (more rarely) bitten or licked by
a cat. It cannot be passed from person to person. Although cats are
popular pets found in about 30 percent of American households, human
infection appears to be rare. One study estimated that for every 100,000
Americans there are only 2.5 cases of cat-scratch disease each year. It is
also unusual for more than one
member to become ill; a Florida investigation discovered multiple cases
in only 3.5 percent of the families studied. Children and teenagers appear
to be the most likely victims of cat-scratch disease, although the
possibility exists that the disease may be more common among adults than
Causes and symptoms
The first sign of cat-scratch disease may be a small blister at the site
of a scratch or bite three to ten days after injury. The blister (which
sometimes contains pus) often looks like an insect bite and is usually
found on the hands, arms, or head. Within two weeks of the
blister's appearance, lymph nodes near the site of injury become
swollen. Often the infected person develops a fever or experiences fatigue
or headaches. The symptoms usually disappear within a month, although the
lymph nodes may remain swollen for several months. Hepatitis,
, and other dangerous complications can arise, but the likelihood of
cat-scratch disease posing a serious threat to health is very small.
patients and other immunocompromised people face the greatest risk of
Occasionally, the symptoms of cat-scratch disease take the form of what is
called Parinaud's oculoglandular syndrome. In such cases, a small
sore develops on the palpebral conjunctiva (the membrane lining the inner
eyelid) and is often accompanied by
(inflammation of the membrane) and swollen lymph nodes in front of the
ear. Researchers suspect that the first step in the development of
Parinaud's oculoglandular syndrome occurs when
bacteria pass from a cat's saliva to its fur during grooming.
Rubbing one's eyes after handling the cat then transmits the
bacteria to the conjunctiva.
A family doctor should be called whenever a cat scratch or bite fails to
heal normally or is followed by a persistent fever or other unusual
symptoms such as long-lasting bone or joint
. The appearance of painful and swollen lymph nodes is another reason for
consulting a doctor. When cat-scratch disease is suspected, the doctor
will ask about a history of exposure to cats and look for evidence of a
cat scratch or bite and swollen lymph nodes. A blood test for
may be ordered to confirm the doctor's diagnosis.
For otherwise healthy people, rest and over-the-counter medications for
reducing fever and discomfort (such as
) while waiting for the disease to run its course are usually all that is
are prescribed in some cases, particularly when complications occur or
the lymph nodes remain swollen and painful for more than two or three
months, but there is no agreement among doctors about when and how they
should be used. If a lymph node becomes very swollen and painful, the
family doctor may decide to drain it.
Most people recover completely from a bout of cat-scratch disease. Further
attacks are rare.
—A drug used for pain relief as well as to decrease fever. A
common trade name for the drug is Tylenol.
Acquired immunodeficiency syndrome (AIDS)
—An infectious disease caused by the human immunodeficiency virus
(HIV). A person infected with HIV gradually loses immune function,
becoming less able to resist other infections and certain cancers.
—Drugs that are designed to kill or inhibit the growth of the
bacteria that cause infections.
—A special protein made by the body's immune system as a
defense against foreign material (bacteria, viruses, etc.) that enters
the body. It is uniquely designed to attack and neutralize the specific
antigen that triggered the immune response.
—Singluar, bacterium; tiny, one-celled forms of life that cause
many diseases and infections.
—An inflammation of the liver, with accompanying liver cell
damage or cell death, caused most frequently by viral infection, but
also by certain drugs, chemicals, or poisons. May be either acute (of
limited duration) or chronic (continuing). Symptoms include jaundice,
nausea, vomiting, loss of appetite, tenderness in the right upper
abdomen, aching muscles, and joint pain. In severe cases, liver failure
—The system of specialized organs, lymph nodes, and blood cells
throughout the body that work together to defend the body against
foreign invaders (bacteria, viruses, fungi, etc.).
—A state in which the immune system is suppressed or not
—Small, bean-shaped collections of tissue located throughout the
lymphatic system. They produce cells and proteins that fight infection
and filter lymph. Nodes are sometimes called lymph glands.
—An infection in which the lungs become inflamed. It can be
caused by nearly any class of organism known to cause human infections,
including bacteria, viruses, fungi, and parasites.
—A thick, yellowish or greenish fluid composed of the remains of
dead white blood cells, pathogens, and decomposed cellular debris. It is
most often associated with bacterial infection.
Gerber, Michael A. "
species (Cat-Scratch Disease, Bacillary angiomatosis, Bacillary
Principles and Practice of Pediatric Infectious Diseases
,2nded. Edited by Sarah S. Long et al. St. Louis, MO: Elsevier, 2003.
Stechenberg, Barbara W. "
Nelson Textbook of Pediatrics.
Edited by Richard E. Behrman et al. Philadelphia: Saunders, 2004.
Lex, Joseph R. "Catscratch Disease."
, December 30, 2003. Available online at
http://www.emedicine.com/emerg/topic84.htm (accessed December 25,