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

• 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 may also be 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.
• Most cases occur in children <15 years of age. Females account for 65% of outpatient cases and 55% of inpatient cases.
• 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).

ETIOLOGY

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

GENERAL PREVENTION

• Avoiding cats is an effective, but impractical, 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.

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.