Scabies

Basics

Description

  • Scabies is a major global health problem in crowded, resource-poor communities and refugee populations
  • Animal scabies (Sarcoptic mange) is transmissible but cannot reproduce on human hosts
  • Gravid females form burrows where they deposit up to 2–3 eggs per day into the stratum corneum along with feces, skin moults, and saliva
  • Secondary infections can occur and are usually due to Staphylococcus aureus or β-hemolytic streptococci and may result in severe renal and cardiac sequelae

Pediatric Considerations

  • Scabies may present differently in children:
    • More inflammatory (vesicular or bullous)
    • Broader distribution including face, scalp, palms, or soles
  • Highest prevalence is in children <2 yr old

Etiology

  • Epidemiology:
    • WHO reports up to 130 million infected at any time
    • Burden of disease is highest in countries with hot, tropical climates, especially where overcrowding and poverty coexist
  • Transmitted by (15–20 min) skin-to-skin contact or, less commonly, from infested bedding or clothing:
    • It is associated with overcrowding and poverty, rather than a reflection of poor hygiene
    • Family members, sexual contacts, and settings such as military barracks, nursing homes, and correctional facilities are at higher risk
  • Symptoms result from delayed (2–6 wk from 1st exposure) type IV hypersensitivity reaction to mite, eggs, saliva, and feces. Those previously infested have a shorter onset to symptoms:
    • Inflammatory reaction leads to intense nocturnal pruritus, which is a hallmark
    • Crusted scabies (Norwegian) is characterized by massive infestation with up to millions of mites, is highly contagious and more common in immunocompromised patients
  • Mites subsist on a diet of dissolved human tissue (do not feed on blood) and can live up to 72 hr off a host’s body
  • On average, the number of mites on a host at any time is ∼5–15 unless crusted (massive infestation)

There's more to see -- the rest of this topic is available only to subscribers.