Crusted scabies is a severe form of scabies that can occur in some persons who are immunocompromised (have a weak immune system), elderly, disabled, or debilitated. It is also called Norwegian scabies. Persons with crusted scabies have thick crusts of skin that contain large numbers of scabies mites and eggs.

Crusted scabies (also called Norwegian scabies) is a highly contagious variant of scabies in which there are thousands or even millions of mites, associated with psoriasiform scaling patches. The patient may complain of severe itching just as is seen in classical scabies, but more commonly, there is minimal to no pruritus.

Scabies can sometimes lead to a secondary skin infection if your skin becomes irritated and inflamed through excessive itching. Crusted scabies is a rare but more severe form of scabies, where a large number of mites are in the skin. This can develop in older people and those with a lowered immunity.