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Last Updated: 8/18/2015  

Scabies

Background
  • Scabies is spread by highly host-specific mites, Sarcoptes scabiei var. hominis, which are translucent, 0.4 by 0.3 mm in size, and just slightly too small to be seen by the naked eye.

  • The entire life cycle of the mite is completed on human skin.

  • The incubation period is 4 to 6 weeks.

Prevention
  • Avoid close contact with persons who possibly have scabies until they have been properly treated.

  • Treat all family members and close contacts simultaneously with the appropriate topical or oral treatment because of the common occurrence of asymptomatic mite carriers.

Diagnosis
  • Ask about unexplained pruritus or exposure to scabies.

  • Look for burrows, which are wavy, threadlike, grayish-white, skin elevations measuring 1 to 10 mm and often capped with a small vesicle at the terminal end. A drop of mineral oil or fountain ink is useful to better demarcate the burrows.

  • Note that burrows are most common in specific locations:

    • Interdigital webbing of the hands

    • Flexural aspect of the wrist

    • Axillae

    • Behind the ears

    • Waist

    • Ankle

    • Feet

    • Buttocks

    • Belt area

    • Penis and scrotum

    • Areolae and nipples

  • Note that other skin manifestations of scabies include excoriations, vesicles, indurated nodules, or eczematous dermatitis.

  • Perform the burrow ink test, or use cyanoacrylate on a glass slide and placed on the skin surface to remove the outer epidermal cells for microscopic evaluation.

Treatment
  • Treat for scabies empirically based on clinical presentation.

  • Prescribe one of the following: permethrin, ivermectin, or lindane.

  • Note that oral ivermectin has high therapeutic efficacy and good tolerance, administration is quick and easy, treatment is convenient for persons who are not self-sufficient or who are bedridden, and no neglected areas of the skin are possibly left untreated. Safety is not documented for pregnant women or children.

  • Treat all family members and close contacts simultaneously with the appropriate topical or oral treatment because of the common occurrence of asymptomatic mite carriers.

DOI: 10.7326/d478
The information included herein should never be used as a substitute for clinical judgment and does not represent an official position of ACP.
Author(s) and Disclosures:
Terri L. Meinking, MD has nothing to disclose. Craig G. Burkhart, MD, MPH has nothing to disclose. Craig N. Burkhart, MD, MSBS has nothing to disclose. Shannon Wood, MD, MPH Department of Internal Medicine, Walter Reed National Military Medical Center
Bethesda, MD
has nothing to disclose.
Meredith Lütz, MD Department of Internal Medicine, Walter Reed National Military Medical Center
Bethesda, MD
has nothing to disclose.
Julie M. Chen, MD, FACP has nothing to disclose.

One or more of the present or past ACP Smart Medicine physician editors worked on this module and had nothing to disclose: Davoren Chick, MD, FACP; Deborah Korenstein, MD, FACP; Marjorie Lazoff, MD, FACP; Richard Lynn, MD, FACP.

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