Cat-scratch disease

Cat-scratch disease (CSD) is a common, self-limiting disease process. Because of the growing population of individuals with impaired immunity, CSD incidence has increased. The estimated incidence of CSD is 24,000 cases per year,' with children the primary group affected. CSD prevalence is higher in warm, humid climates with moderate flea infestation.2 CSD occurs worldwide and throughout the year, but the highest infection rates occur in the fall.?

The causative organism, Bartonella henselae, usually originates from a cat and is transmitted through a scratch or break in the skin.' The common flea is usually the vector of transmission.' Clinical Features

A complete health history is needed to render an accurate diagnosis. Subjective findings may include generalized feelings of anorexia and malaise, headache, abdominal discomfort, or musculoskeletal aches and pains.' Associated CSD symptoms can occur 6 to 8 months after cat contact.6

All CSD cases have some margin of detectable lymphadenopathy. Perform a complete physical examination, concentrating on the area of lymph involvement in the upper extremities including the mandible, neck, axillary, and supraclavicular areas. Lymph node involvement can vary from one to three nodes but rarely involves four or more nodes.' Other objective findings conclusive to CSD are a fever and identification of a nontender, small papule or pustule. Despite the associated name "cat-scratch fever," only 9% of patients experience a fever greater than 1020 F (39 C).7 Differential Diagnosis

The differential diagnosis should concentrate on the presenting symptom of lymphadenopathy. Although lymphadenopathy suggests an infectious process, noninfectious processes may also exist. Lymphadenopathy may result from viral, bacterial, fungal, and protozoan etiologies (see Table). Diagnostic Tests

Tests used to diagnose CSD in the past included fine-needle biopsy, Warthin-Starry stains, cultures of the aspirate, skin tests, enzyme-linked immunosorbent assay (ELISA), and indirect fluorescence antibody (IFA) studies. ELISA and IFA are the most accurate.3 Cultures and WarthinStarry stains are rarely a dependable indicator because of inconsistencies in culture growth and stain organism identification. Skin tests are obsolete and unsafe.8 Diagnosis

Clinical presentation and physical examination findings provide pertinent information in accurately diagnosing CSD. The standard for diagnosis includes three of the following four diagnostic criteria: lymphadenopathy (localized or regional), recent cat contact, inoculation site identification, and positive ELISA or IFA studies.1,4 Treatment

Although studies have indicated accelerated clearing of lymph congestion with treatment, antimicrobial regimens continue to be controversial. Uncomplicated CSD does not require treatment; however, an atypical presentation may require antibiotic therapy

In cases requiring antimicrobial coverage, azithromycin (Zithromax) is the drug of choice. Recommended dosing for children is 10 mg/kg daily dose day one, followed by 5 mg/kg daily dose days two to five. Adult dosing is 500 mg daily dose day one, followed by 250 mg daily dose days two to five. Alternative antibiotics include clarithromycin (Bioxin) and ciprofloxacin (Cipro) in age-appropriate doses.9

Standard CSD treatment does not exist. Individualize the treatment plan specific to the presenting case and patient's age. You may need to consult with an infectious disease specialist. 91 Prevention

CSD can be a modifiable condition with proper prevention, education, and risk factor control. One study identified CSD risk factors as ownership of a kitten, traumatic exposure to the kitten, and the presence of fleas." Interventions such as thorough cleaning of cat scratches and hand washing may lessen the risk of CSD.1 In areas of known flea infestation, active control and impediment of outbreaks is imperative."

REFERENCES

1. Gorenek MJ: Cat scratch disease. Infect Dis Pract Clin 1998;22(1):1-3.

2. Jameson P Green C, Regnery R, et al.: Prevalence of Bartonela henselae antibodies in pet cats throughout regions of North America. Infect Dis 1995;172(10):1145-49.

3. Shenep JL: Cat-scratch disease and Bartonella henselae infections in children. Pediatr Ann 1996;25(9):518-23.

4. Carithers, HA: Cat-scratch disease: An overview based on a study of 1,200 patients. Am J Dis Child 1985;139(11):1124-33.

5. Chomel, BB, Kasten, RW, Floyd-Hawkins K, et al.: Experimental transmission of Bartonella henselae by the cat flea. J Clin Microbiol 1996;34(8):1952-55.

6. Smith DL: Cat-scratch disease and related clinical syndromes. Am Fam Physician 1997;55(5):1783-88.

7. Bass JW, Vincent JM, Person DA: The expanding spectrum of Bartonella infections: 11. Cat-scratch disease. Pediatr Infect Dis J 1997;16(2):163-77.

8. Demers DM, Bass JW, Vincent JM, et al.: Cat-scratch disease in Hawaii. J Pediatr 1995;127(l): 23-26.

9. Gilbert DN, Moellering RC, Sande MA: The Sanford guide to antimicrobial therapy. Hyde Park, Vt.: Antimicrobial Therapy, Inc. 2000;31-48.

10. Zangwill KM, Hamilton DH, Perkins BA, et al.: Cat scratch disease in Connecticut: Epidemiology, risk factors, and evaluation of a new diagnostic test. N Engl J Med 1993;329(l):8-12.

11. Koeholer JE, Galser CA, Tappero JW, et al.: Rochalimaea henselae infection: A new zoonosis with the domestic cat as reservoir. JAMA 1994;271(7):531-35.

ABOUT THE AUTHOR

Michele D. Leidholm, RN, FNP, MSN, is a family nurse practitioner, Medcenter One Health Systems Rural Clinics, Bismarck, N.D.

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