Although the two types of scabies are caused by the same parasite, crusted scabies is a much more serious form of the well-known regular scabies and is often more difficult to treat. Scabies is a very itchy rash caused by a skin parasite known as Sarcoptes scabiei , or itch mite. This tiny, translucent arthropod burrows under the top layer of skin to lay its eggs, and it's highly contagious. Crusted scabies is also known as Norwegian scabies, as it was discovered in Norway in the mid-19th century.
The main difference between common scabies and crusted scabies is the number of mites present on the host. During a regular scabies infestation, despite intense itching, there are usually between five and 50 mites on the host. However, a patient with crusted scabies will often have thousands of mites or more on her body at the same time.
The large number of mites in an individual with crusted scabies is probably due to the victim's immune system. These people often have compromised or weakened immune systems. People at risk include the elderly, people with physical disabilities, and people diagnosed with HIV or AIDS.
The most commonly reported scabies symptom is intense itching in certain areas of the body, which is often worse at night, along with small red bumps. The skin on the affected areas of the body often becomes scaly and begins to peel off. Scabies most often occurs in folds on the body, such as between the fingers and toes, in the armpits, and around the groin. However, in cases of crusted scabies, the rash is often all over the body, and patches of thick, crusty skin usually begin to form. Although there is some itching with crusted scabies, it is often less severe, likely due to the state of the host's immune system.
Treating crusted scabies is usually much more difficult than treating other types of scabies. This is because it is more difficult for topical creams to penetrate crusty and scaly skin and it is difficult to eradicate the large number of mites present on the body. Dermatologists usually start with an agent that softens and breaks down the top layer of crusty skin present in these patients. These are called keratolytic agents, and they often contain salicylic acid.
After the top layer of skin has softened, a topical cream is applied to kill live mites. Permatrin and Lindane are two examples of scabicidal creams. However, Lindane is recommended to be used with caution as it can have some serious side effects such as neurotoxicity. Ivermectin was first used by doctors to rid patients of certain parasites, but recently, dermatologists began using it to successfully treat scabies patients. Antibiotics may also be used if an infection develops anywhere in the body.
It is important to treat other people and areas with whom the victim has close contact, including other household members, children, and significant others. All bedding and clothing should also be thoroughly washed and dried at high temperatures. Carpets and rugs should be vacuumed thoroughly, and vacuum bags should be disposed of immediately. Dermatologists recommend these measures to prevent any re-infestation of the mites.