General Goal: To know the major cause(s) of this disease, how it is transmitted, and the major manifestations of the disease.

Specific Educational Objectives: The student should be able to:

1. recite the most common causes of cat-scratch fever (shape and gram stain?).

2. describe the common means of transmission.

3. describe the major manifestations of this infection.

4. describe how you diagnose, treat and prevent this infection.

Reading: MEDICAL MICROBIOLOGY by P.R. Murray, K.S. Rosenthal, G.S. Kobayashi and M.A. Pfaller, 3rd Edition. pp. 287.

Lecture: Dr. Neal R. Chamberlain

References: 1. eMedicine: Cat Scratch Fever, Joseph R Lex, Jr, MD, Consulting Staff, Department of Emergency Medicine, Chestnut Hill Hospital. http://www.emedicine.com/cgi-bin/foxweb.exe/showsection@d:/em/ga?book=emerg&topicid=84

2. Chomel BB, Abbott RC, Kasten RW, Floyd-Hawkins KA, Kass PH, Glaser CA, Pedersen NC, Koehler JE. 1995. Bartonella henselae prevalence in domestic cats in California: risk factors and association between bacteremia and antibody titers. J Clin Microbiol Sep;33(9):2445-50

3. Bass JW, Freitas BC, Freitas AD, et al. Prospective randomized double blind placebo-controlled evaluation of azithromycin for treatment of cat-scratch disease. Pediatr Infect Dis J. 1998;17:447-452.

4. Jared M. Frandson, MPH, Julie Rawlings, MPH, Christine R. Burgess, MPH, Kate A. Hendricks, MD, MPH&TM; Texas Department of Health, Austin. Cat-Scratch Disease in Texas. 2000. Infect Med 17(10):690-694. http://id.medscape.com/SCP/IIM/2000/v17.n10/m1710.03.fran/pnt-m1710.03.fran.html

5. Jacomo V, PJ Kelly, and D Raoult, Natural History of Bartonella Infections (an Exception to Koch’s Postulate), 2002. Clin Diag Lab Immun, 9:8-18. http://cdli.asm.org/cgi/content/full/9/1/8?view=full&pmid=11777823

Synonyms: cat-scratch disease, benign lymphoreticulosis, nonbacterial regional lymphadenitis.

Bartonella henselae (used to be called Rochalimaea henselae; a rod-shaped Gram negative organism formerly placed int he genus Rochalimaea.)

22,000 cases per year; Incidence equals 6.6 cases per 100,000.

An average of 87 laboratory-confirmed cases of CSD occurred in Texas during1993 and 1994 (4). This figure is higher than the Texas averages for any other reportable zoonotic disease transmitted by arthropod bite or by direct inoculation. For example, during 1993 and 1994, an average of 68 Lyme disease and 38 flea-borne typhus cases per year were reported. Texas surveillance data suggest that CSD is more common than ehrlichiosis, plague, relapsing fever, Rocky Mountain spotted fever, St Louis encephalitis, and tularemia combined.

Generally, cases are pediatric infections associated with a history of scratches from or contact with a cat. 80-90% of the cases are in patient under 21 years of age. 

The organism infects kittens and can remain in their blood stream for long periods of time. Bacteremic cats are more likely to infect their owners via bites or scratches. Cats obtained from warmer parts of the U.S. were more likely to have been infected with Bartonella henselae. 30-50% of the cats from warmer regions (Hawaii, coastal California, Pacific Northwest) have antibodies to the bacterium whereas only 5-7% of cats from cooler regions (Alaska, Midwest, Rocky Mountain region) have antibodies to Bartonella henselae.

Experimental evidence shows that fleas carry B. henselae in their gut and excrete it in their feces and that fleas (Ctenocephalides felis) can transmit B. henselae between cats (4).

A seasonal peak of CSD between late summer and early winter has been reported. This trend could be linked to the life cycles of the feline reservoir or of fleas. Previous studies have shown that exposure to kittens is a greater risk factor than exposure to adult cats (4) and that kittens are more likely than adult cats to be bacteremic.

Bartonella henselae can be transmitted to humans via contact with cats (scratches, bites), and from contact with the cat fleas (Ctenocephalides felis)(5). Person-to-person transmission has not been shown.

Cat-Scratch Disease (CSD)

Incubation period of 1-2 weeks.

Symptoms of classic CSD range from mild to severe. In 50% to 90% of cases, a 0.5 to 1-cm brownish papule or pustule forms at the site of the scratch or bite and is considered an indicator of CSD. Regional lymphadenopathy follows in 3 to 10 days, often accompanied by fever, malaise, and anorexia. Mild fever and malaise occur in less than 50% of the patients. Generally, the lymph nodes are 1 to 5 cm in diameter and proximal to the site of B. henselae inoculation. The most commonly involved nodes are in the axillary, epitrochlear, cervical, and supraclavicular areas. Submandibular and preauricular lymphadenopathy involvment is less common. Over a period of weeks or months, lymph nodes may become fluctuant or suppurative or may spontaneously regress. Full resolution generally occurs within 1 month, with or without treatment. Lymph nodes show hyperplasia, granuloma formation, and suppuration (in about 33% of the cases).

An increasing number of atypical manifestations of B. henselae infection are being recognized and include complications of the CNS, liver, spleen, and lungs (Parinaud oculoglandular syndrome, encephalitis, leber neuroretinitis, neuropathy, endocarditis, pneumonia, Erythema nodosum, relapsing bacteremia)(4). The most serious complication is CSD encephalopathy, manifested as headache, tonic-clonic seizures, combative behavior, and coma. These symptoms typically occur suddenly, 1 to 8 weeks after the onset of lymphadenopathy. CSD encephalopathy occurs in fewer than 8% of all CSD patients. Recovery is usually complete; no deaths from CSD encephalopathy have yet been confirmed.

Other relatively common presentations of CSD include idiopathic stellate neuroretinitis (Leber neuroretinitis), which manifests as a loss of visual acuity with a macular star, and Parinaud oculoglandular syndrome, which manifests as conjunctival inflammation with preauricular adenopathy and a characteristic granulomatous lesion in the conjunctiva. Bartonella infection is thought to be the major cause of both of these ocular conditions. One study suggests that neuroretinitis occurs in 13% of patients with atypical CSD. Parinaud oculoglandular syndrome occurs in about 4% of all CSD patients.

Immunocompromised patients:

• 1) Bacillary angiomatosis ( skin lesion) This disease is also caused by Bartonella quintana the cause of trench fever.
• 2) Peliosis hepatica- (pathology slide)

DIAGNOSIS

1. history of cat contact resulting in a scratch or primary lesion of the dermis eye, or a mucous membrane;
2. a positive skin test response to CSD skin-test antigen or positive indirect fluorescent antibody test to detect B. henselae. This indirect fluourescent antibody test is highly specific. Unfortunately, it can be less than 50% sensitive.
3. negative laboratory investigation (i.e., PPD skin tests and cultures of aspirated pus or lymph nodes) for unexplained lymphadenopathy;
4. and characteristic lymph node lesions.

THERAPY

*If lymph node swelling is extensive recent suggestions for treatment include: azithromycin 500 mg daily for 1 week, then 250 mg once daily for 4 weeks.

*Retinitis- Doxycycline 100 mg twice daily + rifampin 300 mg twice daily x 4-6 weeks.

*Endocarditis- culture positive- Doxycycline 100 mg orally twice daily for 6 weeks + gentamicin 3 mg/kg/d intravenously for 14 days.

Antibiotics can be of benefit in cases of severe disease (encephalopathy); rifampin, ciprofloxacin, trimethroprim/sulfamethoxazole, erythromycin, clarithromycin, or azithromycin.

*Immunocompromised hosts with bacillary angiomatosis - Erythromycin 500 mg once daily for 3 months
or doxycycline 100 mg twice daily for 3 months.

*Immunocompromised hosts with peliosis hepatica- Erythromycin 500 mg once daily for 4 months or doxycycline 100 mg twice daily for 4 months.

*Rolain JM, Brouqui P, Koehler JE, Maguina C, Dolan MJ, Raoult D. 2004. Recommendations for treatment of human infections caused by Bartonella species. Antimicrob. Agents Chemother. 48:1921-1933.

Flea control measures should be undertaken on a regular basis.

Immunocompromised patients considering getting a cat should get an adult indoor cat of known origin rather than a young kitten. Avoid adoption of stray cats that are more likely to scratch and bite while playing.