Scabies

Description

• A contagious parasitic infection of the skin caused by the mite Sarcoptes scabiei, var. hominis
• System(s) affected: skin/exocrine
• Synonym(s): sarcoptic mange

Epidemiology

Incidence
Predominant age: children and young adults

Prevalence varies substantially worldwide but is more common in resource-poor settings (1):

• May be more prevalent in urban areas and areas of overcrowding
• Common in developing countries particularly tropical climates; 2013 added to World Health Organization list of neglected tropical diseases

Etiology and Pathophysiology

• Itching is a delayed hypersensitivity reaction to the mite saliva, eggs, or excrement.
• S. scabiei, var. hominis
  • An obligate human parasite
  • Female mite lays eggs in burrows in the stratum corneum and epidermis.
  • Primarily transmitted by prolonged human-to-human direct skin contact
  • Infrequently transmitted via fomites (e.g., bedding, clothing, or furnishings)

Risk Factors

• Personal skin-to-skin contact (e.g., sexual promiscuity, crowding, nosocomial infection)
• Poor nutritional status, poverty, and homelessness
• Hot, tropical climates
• Seasonal variation: Incidence may be higher in the winter than in the summer (may be due to overcrowding).
• Immunocompromised patients, including those with HIV/AIDS, are at increased risk of developing severe (crusted/Norwegian) scabies.

General Prevention

Prevent outbreaks by prompt treatment and cleansing of fomites (see “Additional Therapies”).