Information on the following diseases can be found in the Related Disorders section of this report:

• Adenitis (Bacterial, Fungal, Pyogenic, and Tuberculous)
• Atypical Mycobacterial Infection
• Brucellosis
• Lymphogranuloma Venereum
• Lymphoma
• Sarcoidosis
• Tularemia
• Atypical Pneumonia
• Encephalitis
• Thrombocytopenia Purpura

The major symptoms of cat-scratch disease may not appear for several days or weeks after exposure. A red spot (macule) may appear on the skin at the site of infection, and may become raised (papule) three to five days after exposure. The papule is painless and does not itch. It may become filled with fluid (vesicle), then crust over and heal with a scar similar to those left by chicken pox. The papule persists for one to three weeks, but may go unnoticed or be attributed to an injury.

A major symptom of cat-scratch disease is swelling and tenderness in the lymph nodes near the bite or scratch (regional lymphadenopathy), usually occuring about two weeks after the initial exposure. Only the lymph nodes nearest to the site of infection are affected, and inflammation of the adjacent lymph vessels (lymphanginitis) does not typically occur. Pus may develop in the involved lymph nodes (suppuration). These nodes usually become very tender and the surface of the skin may appear red and feel hot to the touch.

Other symptoms of cat-scratch disease may include loss of appetite, fatigue, low-grade fever, and/or a generalized feeling of discomfort (malaise). In some cases chills, backache, abdominal pain, and/or convulsions have been reported.

If the site of infection is on the eyelid, cat-scratch-oculoglandular syndrome (Parinaud's syndrome) may develop. Parinaud's syndrome is characterized by swelling of the lymph node in front of the ear (preauricular lymphadenopathy), nonpainful inflammation of the lining of the eyelids (palpebral conjunctivitis), and/or fever.

A more severe, systemic form of cat-scratch disease has been reported. Major symptoms may include prolonged fever, joint pain (arthralgia), rash, weight loss, and/or enlargement of the spleen (splenomegaly).

In some rare cases, symptoms of cat-scratch disease may include swelling of the largest salivary gland (parotid gland), areas of calcium loss from bones (osteolytic lesions), inflammation of the optic nerve and retina (neuroretinitis), acute inflammation of the liver (hepatitis) or the spleen (splenitis), and/or abscesses of the spleen. In very rare cases, cat-scratch disease has been associated with atypical pneumonia, inflammation of the brain (encephalitis), an inflammatory reaction to infection characterized by bumps on the lower legs (erythema nodosum), and/or a skin discoloration associated with a decreased blood platelet count (thrombocytopenia purpura). (For more information on these disorders, see the Related Disorder section of this report.)

Cat-scratch disease is a rare infectious disease that is caused by the bacterium Bartonella henselae. The great majority of cases follow a lick, scratch, or bite from a cat or kitten. In some cases, it is believed that the disease is caused by a tick. A deep puncture wound such as from a thorn or splinter may also introduce infection. There have also been cases reported of the disease following the scratch or bite of dogs and monkeys. In some cases it is thought that fleas may be involved in the transmission of cat-scratch disease. Animals that are carrying the disease are not ill, and will not exhibit any symptoms. Not every person exposed to the carrier animal will develop cat-scratch disease, and in most cases the symptoms are temporary (transient) and mild.

Cat-scratch disease is an infectious disease that affects more males than females. Approximately 80% of diagnosed cases of cat-scratch disease occur in people under 20 years of age, and about 95% have a history of a scratch from a cat or exposure to cats. An estimated 22,000 cases of this disease are diagnosed every year in the United States. However, many cases may go unreported making it difficult to determine the true frequency of this disease in the general population. According to one report, the incidence is estimated to be 6.6 per 100,000 people. Reports of cat-scratch disease cases appear more frequently during fall (September) and winter (February) than during other seasons.

Symptoms of the following disorders can be similar to those of Cat-Scratch Disease. Comparisons may be useful for a differential diagnosis:

Adenitis (Bacterial, Fungal, Pyogenic, and Tuberculous) is an inflammatory disease characterized by inflammation and swelling of lymph glands (lymphadenopathy). Differential diagnosis may be accomplished through skin testing and/or microscopic examination of the involved lymph nodes.

Atypical Mycobacterial Infections are caused by nontuberculous mycobacteria, but can be very difficult to distinguish from tuberculosis. When lymph node disease (lymphadenopathy) is caused by nontuberculous mycobacteria, surgical removal and examination (biopsy) of involved tissue may be necessary for diagnosis.

Brucellosis is an infection of livestock that can be transmitted to humans. It is caused by different species of the bacteria Brucella. Initial infection may result in an acute flu-like illness, or may evolve over months. Untreated cases may take months to resolve, and some cases become chronic. Symptoms may include a gradual onset of fever, weakness, headache, joint pain, and/or night sweats. Other symptoms may include disease of the lymph nodes (lymphadenopathy), enlargement of the spleen (splenomegaly), and/or enlargement of the liver (hepatomegaly). (For more information on this disorder, choose "Brucellosis" as your search term in the Rare Disease Database.)

Lymphogranuloma Venereum is a sexually transmitted infection characterized by a primary skin lesion at the site of infection. This lesion may be a raised bump (papule) that heals spontaneously or may go unnoticed. This is followed by acute pain and swelling of lymph glands (lymphadenopathy) on one or both sides of the body. The site of the first infection or lesion will determine the region affected.

Lymphomas are growths (tumors) of the lymphoid tissue. These tumors are divided into two types, Hodgkin's and non-Hodgkin's lymphoma. Symptoms will depend upon the type and location of the tumor. Symptoms may include pain and/or swelling of the lymph glands (lymphadenopathy), hoarseness, a high- pitched respiratory sound when inhaling (stridor), and/or difficulty in swallowing (dysphagia).

Sarcoidosis is a rare disorder which affects many body systems. It is characterized by small round lesions (tubercles) of granulated tissue. Symptoms may vary depending on the severity of the disease and how much of the body is affected. Symptoms of Sarcoidosis depend on the site of involvement and may be absent, slight, or severe. Enlarged lymph glands (peripheral lymphadenopathy) are common. Both enlarged and normal-sized lymph nodes may contain the characteristic sarcoid tubercles. (For more information on this disorder, choose "Sarcoidosis" as your search term in the Rare Disease Database.)

Tularemia is an infectious disease that primarily affects rodents but may also affect humans. Tularemia is transmitted by the bites of deer flies, fleas, and ticks, and/or as a result of handling contaminated animals or their products. It may also be transmitted by inhalation of the responsible microorganism, or by ingesting contaminated food or water. Ulceroglandular Tularemia begins as a painful raised spot at the site of infection (papule). The papule fills with pus and may rupture to form a shallow ulcer. Mild, generalized pain and swelling of the lymph glands (lymphadenopathy), enlarged spleen (splenomegaly), enlarged liver (hepatomegaly), and/or pneumonia may be associated with Ulceroglandular Tularemia.

The following disorders may be associated with Cat-Scratch Disease as secondary characteristics. They are not necessary for a differential diagnosis:

Atypical Pneumonia is an acute infectious disease of the lungs caused by various microorganisms and viruses. It is characterized by fever, overall discomfort, sore throat, and a cough that is nonproductive at first but becomes productive later in the course of the disease.

Encephalitis is an inflammation of the brain that may develop as a primary disorder or secondary to another disorder. In cases of encephalitis secondary to another disorder, symptoms will vary according to the nature of the primary disorder. Symptoms may include seizures, paralysis, and mental retardation. (For more information on this disorder, choose "Encephalitis" as your search term in the Rare Disease Database.)

Erythema Nodosum is an inflammatory reaction to infection, characterized by multiple tender nodules or bumps on the shins. This reaction occurs most frequently in young women. Acute Erythema Nodosum is often associated with mild generalized symptoms such as fever, overall discomfort (malaise), and joint pain (arthralgia).

Thrombocytopenia Purpura is a disorder in which the blood platelet count is decreased. It may be either a primary disorder or secondary to another disorder. Symptoms may include non-raised round purplish spots (petechiae) on the skin and/or a tendency to bruise easily.

The diagnosis of Cat-Scratch Disease usually depends on the individual's symptoms, such as a history of contact with animals (usually a cat), a skin test positive for Cat-Scratch Disease, examination of fluid extracted from an involved lymph node, and/or characteristic changes in the involved lymph nodes.

Cat-Scratch Disease may subside without any treatment, usually within four to eight weeks. Therapy is symptomatic and supportive. Cat-Scratch Disease usually has a very good prognosis, with no long-term health effects. When secondary disorders (i.e., encephalitis) develop, the secondary disorder is usually resolved when the lymphadenopathy and associated symptoms are resolved.

The effectiveness of antimicrobial therapy has not been established in the treatment of Cat-Scratch Disease. Some reports show, however, that drugs such as ciprofloxacin, gentamicin, and/or a combination of trimethoprim and sulfamethoxazole may be useful in the treatment of systemic symptoms secondary to Cat-Scratch Disease. Antibiotic therapy may speed the resolution of the symptoms of Cat-Scratch Disease.

If the affected lymph node produces pus (suppurates) and becomes large and/or painful, it may be necessary to drain the node. Draining the pus through a needle (aspiration) is preferred over making an incision. Usually one aspiration is sufficient to relieve discomfort.

Researchers are studying genetics and the immune system in order to understand why some people may be vulnerable to infections such as cat-scratch cisease, while others exposed to the same infectious animal seem to be immune to the same infection. A new test to detect antibodies to Bartonella henselae, the bacteria that is thought to cause cat-scratch disease, is available in some parts of the United States. A high level of these antibodies in the blood suggests that a person has cat-scratch disease. New techniques to culture and grow this bacterium are also being investigated.

Information on current clinical trials is posted on the Internet at www.clinicaltrials.gov. All studies receiving U.S. government funding, and some supported by private industry, are posted on this government web site.

For information about clinical trials being conducted at the NIH Clinical Center in Bethesda, MD, contact the NIH Patient Recruitment Office:

Tollfree: (800) 411-1222
TTY: (866) 411-1010
Email: prpl@cc.nih.gov

TEXTBOOKS
NELSON TEXTBOOK OF PEDIATRICS, 14th Ed.: Richard E. Behrman, Editor; W.B. Saunders Company, 1992. Pp. 863-864.

DISEASES OF THE NOSE, THROAT, EAR, HEAD & NECK, 14th Ed.: John Jacob Ballenger; Lea & Febiger, 1991. P. 302.

OPHTHALMOLOGY: PRINCIPLES AND CONCEPTS, 7th Ed.: Frank W. Newell; Mosby Year Book, 1991. P. 230.

CLINICAL DERMATOLOGY, 2nd Ed.: Thomas P. Habif, Editor; The C.V. Mosby Company, 1990. P. 396.

DICTIONARY OF MEDICAL SYNDROMES, 3rd Ed.: Sergio I. Magalini, Sabina C. Magalini, and Giovanni de Francisci, Editors; J.B. Lippincott Company, 1990. Pp. 670, 684-685.

ANTIMICROBIAL THERAPY FOR PARINAUD'S OCULOGLANDULAR SYNDROME. M. Jackson et al.; CD ROM Version of Pediatric Infectious Disease Journal (Feb 1992; II(2)). P. 402.

CAT-SCRATCH ADENITIS. C.M. Ginsberg; CD ROM Version of Pediatric Infectious Disease Journal (Sep/Oct 1984; 3(5)). P. 209.

JOURNAL ARTICLES
Tsujine K, et al. Clinical implication of prolonged fever in children with cat scratch disease. J Infect Chemother. 2004;10:227-33.

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

Wheeler SW, et al. Cat-scratch encephalopathy. Neurology. 1997;49:876-8.

Zangwill KM, et al. Cat-scratch disease in Connecticut. N Eng J Med. 1993;329:8-13.

Holley Jr. HP. Successful treatment of cat-scratch disease with ciproflaxin. JAMA. 1991;265:1563-5.

Bogue CW, et al. Antibiotic therapy for cat-scratch disease? JAMA. :1989;262:813-6.