National Center for Advancing and Translational Sciences Genetic and Rare Diseases Information Center, a program of the National Center for Advancing and Translational Sciences

Crusted scabies

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Other Names:
Norwegian scabies; Seven year itch
Crusted scabies (also called Norwegian scabies) is an infestation characterized by thick crusts of skin that contain large numbers of scabies mites and eggs.  It is a severe form of scabies that occurs most often in people who have a weakened immune system or a neurological disease, the elderly, and the disabled. The symptoms of the more common form of scabies, such as itching and a rash, may be absent. Crusted scabies is very contagious and can spread both by direct skin-to-skin contact and through contaminated items such as clothing, bedding, and furniture.[1][2] It is caused by super-infestation with Sarcoptes scabiei var hominis, a mite that can only reproduce on humans.  People with crusted scabies should receive quick and aggressive medical treatment for their infestation to prevent future outbreaks of scabies.[1] Ivermectin, a drug used to treat parasitic infections, is commonly used for treatment.[2]
Last updated: 6/17/2019
Crusted scabies may be particularly difficult to treat. Patients with crusted scabies may be instructed by their doctors to remove scaling skin so that topical medications can penetrate the skin more easily.[3] Repeated applications of a topical medication or combined treatment with a topical and an oral medication for several weeks or longer may be necessary.[3][4] Patients who still have signs of infection after one month may need additional treatment. Infants and pregnant women should be treated for scabies only if the benefit is determined to outweigh the risk and if the diagnosis is confirmed by biopsy.[3] 

A dermatologist or infectious disease physician should be involved in the care of the patient and those with whom they have had close contact. Treatment of crusted scabies should be done in an inpatient or residential setting, with the patient in a private room.Treatment includes oral Ivermectin and topical insecticides.

Last updated: 6/17/2019

Research helps us better understand diseases and can lead to advances in diagnosis and treatment. This section provides resources to help you learn about medical research and ways to get involved.

Clinical Research Resources

  • ClinicalTrials.gov lists trials that are related to Crusted scabies. Click on the link to go to ClinicalTrials.gov to read descriptions of these studies.

    Please note: Studies listed on the ClinicalTrials.gov website are listed for informational purposes only; being listed does not reflect an endorsement by GARD or the NIH. We strongly recommend that you talk with a trusted healthcare provider before choosing to participate in any clinical study.

These resources provide more information about this condition or associated symptoms. The in-depth resources contain medical and scientific language that may be hard to understand. You may want to review these resources with a medical professional.

Where to Start

  • You can obtain information on this topic from the Centers for Disease Control and Prevention (CDC). The CDC is recognized as the lead federal agency for developing and applying disease prevention and control, environmental health, and health promotion and education activities designed to improve the health of the people of the United States.
  • DermNet NZ is an online resource about skin diseases developed by the New Zealand Dermatological Society Incorporated. DermNet NZ provides information about this condition.
  • MedlinePlus was designed by the National Library of Medicine to help you research your health questions, and it provides more information about this topic.

In-Depth Information

  • Medscape Reference provides information on this topic. You may need to register to view the medical textbook, but registration is free.
  • The Monarch Initiative brings together data about this condition from humans and other species to help physicians and biomedical researchers. Monarch’s tools are designed to make it easier to compare the signs and symptoms (phenotypes) of different diseases and discover common features. This initiative is a collaboration between several academic institutions across the world and is funded by the National Institutes of Health. Visit the website to explore the biology of this condition.
  • PubMed is a searchable database of medical literature and lists journal articles that discuss Crusted scabies. Click on the link to view a sample search on this topic.

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  1. What is crusted (Norwegian) scabies?. Centers for Disease Control and Prevention (CDC). November 2, 2010; http://www.cdc.gov/parasites/scabies/gen_info/faqs.html#crusted.
  2. Oakley A. Scabies. DermNet NZ. 2016; http://www.dermnetnz.org/arthropods/scabies.html.
  3. Barry M. Scabies. Medscape Reference. November 18, 2015; http://emedicine.medscape.com/article/1109204-overview.
  4. Scabies. DermNet New Zealand Trust. 2016; http://www.dermnetnz.org/arthropods/scabies.html.
  5. Thoma L. Crusted scabies. DermNet NZ. June, 2016; http://www.dermnetnz.org/topics/crusted-scabies/.