Cat scratch disease


Bacterial infection associated with subacute solitary or regional lymphadenopathy.

Causative organism Bartonella henselae, a gram negative bacterial rod.

Cat scratch disease occurs worldwide.

Cats are the main reservoir of Bartonella henselae, and the bacterium is transmitted to cats by the cat flea Ctenocephalides felis.

Cat-scratch disease is a bacterial disease that people may get after being bitten or scratched by a cat.

About 40% of cats carry the bacteria Bartonella henselae some time in their mouths, although kittens younger than one year of age are more likely to have it.

Most cats with this infection show no signs of illness.

Incidence about 9.3 per 100,000 people per year.

Approximately 22,000 cases annually and about 2000 hospitalizations per year in the U.S.

Usually associated with history of sustaining a scratch or bite from a cat or kitten.

Infection in cats is very common with a prevalence estimated between 40-60%, younger cats being more commonly infective.

Cats usually become immune to cat scratch disease infection.

Kittens are the main reservoir of B. henselae, and they transmit the bacteria through their saliva were through scratching.
Approximately 50% of cancer patients are seropositive for B. henselae

Patients are most commonly less than 10 years of age.

Associated with regional lymphadenopathy proximal to site of inoculation injury.

Bartonella infection causes granulomatous and suppurative reaction.

Reaction can have proliferation of the vasculature and revascularization.

Most cases occur in the fall and winter.

More prevalent in areas with warm and humid conditions.

Typically benign and self limited in patients with normal immune system.

It is associated with a skin lesion that forms 3-10 days after the inoculation and may be a papule, vesicle, or pustule.

Skin lesions are not always identified, and approximately two weeks after inoculation, regional lymphadenopathy develops.

CSD often resolves spontaneously without treatment.

Most patients have 1-3 or more 3-5 mm red-brown nontender papules that develop 3-10 days after the exposing injury.

Lymphadenopathy usually develop 1-3 weeks in the draining nodal site.

The involved node can be tender and the skin over the area may be erythematous and warm.

Tender regional lymphadenopathy is present in 85-90% of cases.

The enlarged lymph node is painful and tender.

The most commonly involved sites of lymphadenopathy are: the axillary, epittrochlear, cervical, sub curricular, and submandibular regions.

Generalized out in apathy is rare, but up to 1/3 of cases involves more than one anatomical site.

The lymph nodes may suppurate, some patients may remain afebrile or asymptomatic.

Other presentations include fever, particularly in children, Parinaud’s oculoglandular syndrome, encephalopathy, and neuroretinitis.

Infectious entrance site is visible in about 50% of cases.

Resolution of lymphadenopathy occurs within 2-4 months in most cases, but may take as long as 12 months.

Incubation period for lymph node manifestations 7-60 days (with a mean average number of 14 days) after exposure.

In approximately 10% of cases suppuration of the nodal area may occur.

Symptoms are usually resolve in 2-4 months.

5-25% of patients have of sites other than the regional lymph nodes.

Patients may have systemic symptoms.

B. henselae can be associated with bacteremia, bacillary angiomatosis, and hepatis in HIV patients, and bacteremia and endocarditis in immunocompetent and immunocompromised patients.

Patients older than 60 years may present with atypical features.

Immunocompromised patients may have more serious infections with B henselae, or Bartonella quintana.

More common in white people.

60% of cases in males.

55% aged 18 or younger.

Associated with hospitalization rate of 0.6 per 100,000 patients younger than 18 years and 0.86 per 100,000 patients younger than 5 years (Reynolds).

Neurological manifestations may occur with acute seizures, status epilepticus, encephalopathy, or hemiparesis.

Interval between lymph node manifestation and CNS manifestations is one to six weeks.

CSF analysis is normal in 70% of cases.

Diagnosis bases mainly on presence of typical history of exposure to cats or fleas.

Testing for B. henselae helps in diagnosis, with a IgG antibody titter greater than 1:256 strongly suggestive of diagnosis.

The detection of B. henselae by PCR DNA is diagnostic.

Azithromycin antibiotic agent of choice.

Treatment is typically five days for uncomplicated disease.

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