Crusted (Norwegian) scabies is a rare, severe form of scabies. It is extremely contagious because of the large number of mites found in and on the skin.

This form of scabies may occur in:

• People who have certain nutritional disorders, infectious diseases, leukemia, or weakened immune systems (such as people who have AIDS). Testing for HIV infection may be appropriate for people who have this type of scabies.
• People who have mental or nervous system disorders that mask the itching sensation. When scabies itching goes undetected, the infestation can become severe.

Characteristics of this form of scabies include:

• Scaly, crusted sores on the hands, feet, scalp, face, torso, and pressure-bearing areas such as the elbows. Facial skin may flake off, and significant hair loss can result.
• Severe itching, though a few people experience mild itching or none at all.
• Slow response to treatment compared with other forms of scabies. When multiple treatments are ineffective, oral treatment with the medication ivermectin may be used.