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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.
- 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.
- 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
- 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.
- 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.
The etiologic agent is B. henselae, a fastidious, small, curved, pleomorphic gram-negative bacillus.