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Although the two types of scabies are both caused by the same parasite, crusted scabies is a much more severe form of the well known regular scabies and is often harder 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 underneath the top layer of skin to lay its eggs, and it is very contagious. Crusted scabies is also known as Norwegian scabies, as it was discovered in Norway during the mid 1800s.
The main difference between common scabies and crusted scabies is the number of mites present on the host. During a regular scabies infestation, despite the intense itching, there are typically between five and 50 mites on the host. A patient with crusted scabies, though, will often have thousands of mites or more on his body at one time.
The large number of mites on an individual with crusted scabies is most likely due to the sufferer's immune system. These individuals often have compromised or weakened immune systems. At-risk individuals include elderly people, people with physical disabilities, and people diagnosed with HIV or AIDS.
The most commonly reported scabies symptom is an intense itching on certain areas of the body, which is often worse at night, along with small red bumps. The skin on affected areas of the body often becomes scaly and begins to flake off. Scabies is most often present in folds on the body, such as between fingers and toes, in the armpits, and around the groin. In cases of crusted scabies, however, the rash often becomes present all over the body, and patches of thick, crusty skin will usually begin to form. Although there is some itching with crusted scabies, it is often less severe, which is most likely due to the state of the immune system of the host.
Treating crusted scabies is generally much more difficult than treating other types of scabies. This is because it is harder for topical creams to penetrate the crusted, scaly skin and it is difficult to eradicate the large number of mites present on the body. Dermatologists will usually start with an agent that softens and breaks down the top layer of crusty skin present on these patients. These are called keratolytic agents, and they will often contain salicylic acid.
After the top layer of skin has been softened, a topical cream is applied to kill any live mites. Permathrin and lindane are two examples of scabicidal creams. It is recommended, however, that lindane be used with caution, as it can have some serious side effects, like 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 on any part of the body.
Treating other individuals and areas with which the sufferer has close contact, including other household members, children, and significant others, is important. All bedding and clothing should also be washed and dried thoroughly at high temperatures. Rugs and carpets should be vacuumed well, and the vacuum bags should be disposed of immediately. These measures are recommended by dermatologists to prevent any reinfestation of the mites.