Many people think that there are different kinds of scabies, but the truth is there is only one type of mite that causes the condition, which is the Sarcoptes scabiei mite. When talking about the classification or types of scabies, what they usually refer is the different ways that the rash can appear. These include:1
• Typical scabies. These are itchy rashes that appear on the hands, wrists and elsewhere; however, the scalp and face are spared.
• Nodular scabies. This type appears as itchy bumps in the groin, armpits and genital areas.
• Infantile scabies. A scabies infestation that appears on a child or infant, and are most often characterized by rashes on the hands and feet, as well as the face and scalp.
Another type is complicated scabies, and unlike the others, it does not specify where the rash occurs – rather, this is when scabies occurs with another skin-related condition, such as dermatitis, urticaria, or impetigo (infection).
Scabies may also be classified according to where the infestation breaks out. For example, scabies that affects occupants of a residential facility, such as boarding schools, rest homes, hospitals, prisons and camps is called institutional scabies.2
The most severe type of scabies is crusted scabies. Also known as Norwegian scabies, as it was first identified in Norway during the mid-19th century,3 this severe condition usually occurs in people who are immunocompromised, particularly the elderly, disabled or debilitated.
Instead of the typical bumpy rashes seen in scabies patients, people with Norwegian scabies have thick crusts all over their skin, which have large numbers of mites and eggs thriving underneath. These crusts can actually house hundreds or thousands of mites and their eggs.4
The crusty skin caused by Norwegian scabies is most commonly found between the fingers, on the wrists and elbows. In women, it may appear on the breasts, and in men, the crusts may form on their scrotum. The itch brought on by this condition is very minimal compared to typical scabies. In some cases, there may be no itch at all.
Norwegian scabies may spread easily through direct skin-to-skin contact, or by using or touching the contaminated items (such as the beddings, clothes or furniture) of a person who has this illness. This condition requires immediate treatment to prevent it from causing further harm.