• Infestation by organisms that live in close association with host
  • Bites are painless
  • Signs and symptoms result from host response to saliva and anticoagulant injected during feeding
  • Transmitted by direct contact and fomites (inanimate objects)
  • Head lice are transmitted by head-to-head contact:
    • Combs
    • Pillows
    • Hats
  • Head lice are more common in children and females
  • Pubic lice are transmitted by sexual contact
  • Obligate human parasites cannot survive away from hosts >7–10 d


Infestation by:
  • Pediculus capitis (head louse):
    • Most common
    • All socioeconomic groups
  • Pediculus corporis (body louse):
    • Associated with poverty, poor hygiene, and overcrowding
    • Live in clothing and transfer to human host for feeding
    • Related to bed bugs
  • Phthirus pubis (pubic or crab louse)

Pediatric Considerations
Pubic lice may also indicate sexual abuse in children

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