Basics
Description
Cat-scratch disease (CSD) is a zoonotic infection caused by Bartonella henselae, which most commonly causes a subacute, regional lymphadenitis syndrome but is also more rarely associated with visceral organ, neurologic, and ocular manifestations.
Epidemiology
- Domestic cat is the primary reservoir for B. henselae and the major vector for transmission to humans.
- CSD most commonly results from a cat scratch or bite; flea bites are also implicated in the transmission of CSD.
- Kittens are more likely to transmit the organism than adult cats.
- 90% of patients with CSD have history of recent cat contact.
- Person-to-person transmission is not thought to occur.
- More common in males
- Most cases of CSD occur in the fall and winter.
Incidence
- There are ~22,000 cases each year; annual incidence of CSD is 3.7/100,000 persons.
- Most cases occur in those <21 years of age. Children younger than 10 years of age have highest age-specific annual attack rate (9.3/100,000).
- Most common cause of subacute/chronic regional lymphadenitis in U.S. children
General Prevention
- Avoiding cats is an effective, but unpractical, method of preventing CSD; declawing cats can also be considered.
- Cat bites and scratches should be immediately and thoroughly cleaned.
- Immunocompromised individuals should avoid contact with cats that scratch or bite and avoid kittens as new pets.
- Care of cats should involve effective flea control.
Pathophysiology
- Infection can result in local invasion, causing lymphadenopathy, or disseminated infection, leading to visceral organ spread.
- Involved nodes initially develop generalized lymphoid hyperplasia, followed by the development of stellate granulomas; the centers are acellular and necrotic and may be surrounded by histiocytes and peripheral lymphocytes.
- Progression leads to microabscesses, which may become confluent and lead to pus-filled pockets within the infected nodes.
Etiology
The etiologic agent is B. henselae, a fastidious, small, curved, pleomorphic gram-negative bacillus.
Diagnosis
History
- Cat contact
- 90% of patients have an antecedent cat contact.
- A skin rash
- A red papule generally appears on the skin at the site of inoculation 7-12 days after the initial cat scratch.
- This papule persists for 1-4 weeks, often progresses through a vesicular and crusty stage, and then regresses spontaneously.
- Appearance of large lymph nodes
- Within 1-4 weeks after appearance of a skin lesion, lymphadenopathy in the region of drainage (generally immediately proximal to the skin lesion) is often noted.
- Other symptoms
- Most persons with CSD do not have fever or other constitutional symptoms; fever and mild systemic symptoms (such as generalized achiness, malaise, and anorexia) are present in up to 30% of patients.
Physical Exam
- An erythematous papule at the inoculation site may be detectable.
- Chronic or subacute lymphadenitis involving the 1st or 2nd set of nodes draining the inoculation site is present in approximately 90% of cases:
- The groups affected, in decreasing order of frequency, are the axillary, cervical, submandibular, periauricular, epitrochlear, femoral, and inguinal lymph nodes.
- Affected nodes are usually tender, with overlying erythema, warmth, and induration.
- ~10-30% spontaneously suppurate or form a sinus tract to the skin.
- The finding of conjunctivitis/conjunctival granuloma along with ipsilateral preauricular lymphadenitis is a unique presentation of CSD (Parinaud oculoglandular syndrome), in which the conjunctiva or eyelid is the site of inoculation.
Diagnostic Tests & Interpretation
Lab
- Indirect fluorescence antibody (IFA) testing
- For detection of serum antibodies to B. henselae
- Available at many commercial laboratories and the Centers for Disease Control and Prevention
- Can be used to confirm CSD
- A single IgG titer of ≥1:512, a 4-fold rise in titer, or seroconversion is necessary for serologic diagnosis of CSD.
- IgM titers are less sensitive than IgG titers, even in acute disease.
- Overall sensitivity and specificity of IFA IgG testing is 88% and 98%, respectively.
- Enzyme immunoassay (EIA) testing
- Also for detection of serum antibodies to B. henselae
- Similar sensitivity and specificity to IFA
- Blood cultures
- Using lysed or centrifuged blood may, at times, yield B. henselae growth from infected individuals in whom bacteremia is suspected.
- Growth typically is obtained on blood agar after 12-15 days but may require incubation period of up to 45 days.
- Polymerase chain reaction (PCR)
- Available in some commercial and research laboratories
- Sensitive and specific method for diagnosis of Bartonella infection in tissue specimens (e.g., needle aspiration of lymph node)
- Histologic findings of lymph nodes are characteristic of CSD but not pathognomonic.
- Early findings include lymphocytic infiltration with epithelioid granulomas.
- Later findings include neutrophilic infiltration with necrotic granulomas (stellate microabscesses).
- Warthin-Starry silver stain
- May demonstrate B. henselae bacilli in chains, clumps, or filaments within necrosed areas of lymph node or within primary inoculation site of the skin
- Not specific for B. henselae and not definitively diagnostic of CSD but is strongly suggestive in conjunction with compatible clinical findings
Differential Diagnosis
- Includes infectious and noninfectious causes of lymphadenopathy
- Mycobacterial infection (Mycobacterium tuberculosis and non-tuberculous mycobacterial infection)
- Malignancy, especially lymphoma
- Acute bacterial lymphadenitis caused by Staphylococcus aureus and Streptococcus pyogenes)
- Tularemia
- Viral causes of lymphadenopathy such as EBV, CMV, or HIV
- Toxoplasmosis
Treatment
Medication
- Antimicrobial therapy may hasten recovery in acutely or severely ill patients with systemic symptoms and is recommended for all immunocompromised people.
- Macrolides, doxycycline, ciprofloxacin, and trimethoprim-sulfamethoxazole appear to be effective.
- Rifampin may be effective but is often used in combination with a macrolide or doxycycline.
- Azithromycin or doxycycline is recommended for patients with bacillary angiomatosis and bacillary peliosis.
- The optimal duration of therapy for complicated infections is not clear but may be prolonged for systemic disease.
- Azithromycin (500 mg initially then 250 mg daily for a total of 5 days in patients >45.5 kg and 10 mg/kg on the 1st day and 5 mg/kg for the subsequent 4 days in patients ≤45.5 kg) has been shown to be of modest clinical benefit in children with uncomplicated CSD and is recommended by some experts.
Additional Therapies
General Measures
- The management of typical CSD is supportive.
- Many experts suggest conservative, symptomatic treatment only, except in severe or systemic disease or in immunocompromised patients.
Issues for Referral
- Consider infectious disease consult to aid in evaluation, diagnosis, and management, especially in complicated disease or in immunocompromised hosts.
- Consider general surgery consult for needle aspiration if needed.
Surgery/Other Procedures
- Percutaneous needle aspiration of painful, fluctuant nodes can be performed for relief of pain.
- Incision and drainage should be avoided to reduce the risk of sinus tract formation, and surgical excision is generally not necessary.
Inpatient Considerations
Admission Criteria
- Severe pain refractory to oral analgesics
- Workup to rule out serious other causes of lymphadenopathy or symptomatology
- Severe or unusual complications of CSD
Discharge Criteria
- Pain under adequate control
- No concern for serious or life-threatening complications or other disorders requiring further evaluation or treatment
Ongoing Care
Follow-up Recommendations
- Typical CSD is self-limited. Slow resolution of enlarged or painful lymph nodes will occur over 2-4 months.
- ~10-30% of affected lymph nodes will spontaneously suppurate.
Prognosis
- Most immunocompetent patients have a benign course with complete recovery.
- Patients with significant complications, such as encephalopathy, thrombocytopenic purpura, or bone lesions, usually have a more prolonged course but generally have a good long-term prognosis.
Complications
- Systemic CSD
- Usually characterized by fever, arthralgia, malaise, myalgia, and hepatosplenic involvement
- Cause of fever of unknown origin (FUO) in children
- Hepatosplenic involvement may manifest with abdominal pain; microabscesses or granulomas may be visualized on ultrasound or CT of the liver and spleen.
- Encephalopathy/encephalitis
- May occur 1-3 weeks after the initial symptoms of CSD
- Seizures, lethargy, combative behavior, and coma may occur.
- CSF analysis typically normal or slight lymphocytic pleocytosis and elevated protein
- Recovery is generally complete.
- Optic neuritis or neuroretinitis
- Acute (usually unilateral) painless vision loss
- Associated with stellate macular exudates
- Erythema nodosum
- Likely represents a delayed hypersensitivity reaction to the infection
- Most often involves the subcutaneous fat of the legs and, at times, dorsum of arms, hands, and feet
- Osteolytic bone lesions
- Endocarditis
- Other, rare complications
- Thrombotic thrombocytopenic purpura
- Henoch-Sch ¶nlein purpura
- Mesenteric lymphadenitis
- Pneumonia
- Osteomyelitis
- Hypercalcemia
- Guillain-Barr © syndrome
- Transverse myelitis
- Endocarditis
- Bacillary angiomatosis and bacillary peliosis can occur in the immunocompromised host.
Additional Reading
- American Academy of Pediatrics. Cat-scratch disease (Bartonella henselae). In: Pickering LK, Baker CJ, Kimberlin DW, et al, eds. Red Book: 2012 Report of the Committee on Infectious Diseases. 29th ed. Elk Grove Village, IL: American Academy of Pediatrics; 2012:269-271.
- 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(6):447-452. [View Abstract]
- Biswas S, Rolain JM. Bartonella infection: treatment and drug resistance. Future Microbiol. 2010;5(11):1719-1731. [View Abstract]
- Ciervo A, Mastroianni CM, Ajassa C, et al. Rapid identification of Bartonella henselae by real-time polymerase chain reaction in a patient with cat scratch disease. Diagn Microbiol Infect Dis. 2005;53(1):75-77. [View Abstract]
- English R. Cat-scratch disease. Pediatr Rev. 2006;27(4):123-127. [View Abstract]
- Forin TA, Zaoutis TE, Zaoutis LB. Beyond cat scratch disease: widening spectrum of Bartonella henselae infection. Pediatrics. 2008;121(5):e1413-e1425. [View Abstract]
- Schutze GE. Diagnosis and treatment of Bartonella henselae infections. Pediatr Infect Dis J. 2000;19(12):1185-1187. [View Abstract]
Codes
ICD09
- 078.3 Cat-scratch disease
- 078.3 Cat-scratch disease
ICD10
- A28.1 Cat-scratch disease
SNOMED
- 79974007 Cat scratch disease (disorder)
FAQ
- Q: Can a sibling develop CSD from an infected patient?
- A: No. There is no evidence of person-to-person transmission. However, asymptomatic household contacts of the index case are more likely to be seropositive than the general population, likely related to exposure to the same animal.
- Q: Should the parents of a child with CSD get rid of the cat?
- A: In general, this is not recommended. These animals are not ill; the capacity to transmit disease appears to be transient, and recurrent disease is rare.
- Q: What is the benefit of azithromycin in the treatment of uncomplicated CSD lymphadenitis?
- A: In a prospective, randomized, double-blind study, azithromycin given for 5 days was shown to result in significantly greater decrease in lymph node volume during the 1st month of treatment as compared to placebo. However, there was no difference in outcome between the 2 groups after 30 days.