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- A contagious parasitic infection of the skin caused by the mite Sarcoptes scabiei, var. hominis
- Typically, a clinical diagnosis based on history and physical exam
- System(s) affected: skin/exocrine
Predominant age: children, sexually active young adults, and the elderly
Prevalence varies substantially worldwide but is more common in resource-poor settings (1):
- More prevalent in areas of overcrowding and in developing countries, particularly tropical climates
- Added to World Health Organization list of neglected tropical diseases in 2013
Etiology and Pathophysiology
- S. scabiei, var. hominis
- An obligate human parasite
- Primarily transmitted by prolonged human-to-human direct skin contact
- Infrequently transmitted via fomites (e.g., bedding, clothing, or furnishings)
- Female mite lays eggs in burrows in the stratum corneum and epidermis.
- Itching is caused by a delayed type IV hypersensitivity reaction to the mite saliva, eggs, or excrement.
- Prolonged skin-to-skin contact (e.g., sexual, overcrowding, nosocomial infection)
- Poor nutritional status, poverty, and homelessness
- Hot, tropical climates
- Seasonal variation: Incidence may be higher in the winter than in the summer (due to overcrowding).
- Immunocompromised patients, including those with HIV/AIDS, are at increased risk of developing severe (crusted/Norwegian) scabies.
Prevent outbreaks by prompt treatment and cleansing of fomites (see “General Measures”).