Cat-Scratch Disease



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.


  • Cats are 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 transmission.
  • Kittens are more likely to transmit the organism than adult cats.
  • 90% of patients with CSD have history of recent cat contact, most commonly with an apparently healthy kitten.
  • Person-to-person transmission is not thought to occur.
  • More common in males
  • Most cases of CSD occur in the autumn and winter.
  • Incubation period is 7 to 12 days (from time of the scratch to appearance of primary skin lesion).


  • There are an estimated 12,000 cases annually in the United States each year.
  • Incidence highest among those living in the southeastern United States (6.4/100,000 persons) and in children aged 5 to 9 years (9.4/100,000 persons).
  • Most common cause of subacute/chronic regional lymphadenitis in U.S. children


  • Avoiding cats is an effective, but unpractical, method of preventing CSD.
  • Cat bites and scratches should be immediately and thoroughly cleaned.
  • Immunocompromised individuals should avoid contact with cats that scratch or bite; avoid kittens as new pets and stray cats.
  • 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.

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