If the itch mites are not controlled when symptoms first appear, they multiply during the next two months. During that time, the itching is correspondingly worsened. Then, the number of mites in the skin decreases steadily over a long period of time and eventually they will disappear and the itching will stop by itself. It is believed that two factors: scratching and immunization play important roles in this process. Usually, the itching automatically leads to controlling the mites much earlier.
In the type of scabies called Norwegian scabies, the two above-mentioned factors apparently do not work as intended. The itch mites multiply aggressively and the patient does not feel the irritation of the skin which causes other infected people to scratch and seek medical aid at an early stage. Norwegian scabies requires the help of a dermatologist. Common scabies can be controlled without seeking medical aid.