Scabies is the most medically important mite in humans.
- Infestation of the skin is caused by the human itch mite (Sarcoptes scabiei var. hominis).
- Adult females burrow into the upper layer of the skin (epidermis) where they live and deposit their eggs.
- During a patient exam, remove the mite from the end of its burrow using a needle tip or obtain a skin scraping to examine under a microscope for mites, eggs, or fecal matter (scybala). (Note that a person may still be infested even if no mites or eggs are found.)
- Humans are the source of infestation; animals do not spread human scabies.
- Humans spread scabies via prolonged skin-to-skin contact. Scabies may be sexually acquired or may spread in crowded conditions, such as in nursing homes, childcare facilities, and prisons.
Crusted (Norwegian) Scabies
A severe form of scabies may be found in the elderly or immunocompromised individuals. Thick crusts of skin that contain large numbers of scabies, mites, and eggs are present.
16. CDC. Image# 15344. (1976). "This photomicrograph reveals a single, human itch mite, Sarcoptes scabiei var. hominis, in a case of what is commonly referred to as scabies, that had burrowed itself into the epidermal layers of a skin tissue sample." PHIL public domain. https://phil.cdc.gov/Details.aspx?pid=15344
