Also called the itch mite, Sarcoptes scabiei is a parasitic arthropod that burrows into the skin and causes scabies. The scabies mite is found all over the world and can infect humans and other mammals such as dogs, cats, etc.
Severe itching of the skin, or pruritus, is the most common presenting symptom of scabies infections because the mites burrow under the skin and cause inflammation. This is a form of type IV hypersensitivity reaction.
The scabies mites burrow underneath the skin and create papules. The burrows are caused by female scabie mites tunneling just beneath the skin surface. The burrows often appear as tiny, raised, crooked (serpiginous) gray-white or skin colored lines. These papules most often appear in warmer regions and creases of the body, often where skin meets skin such as between the fingers, in the axilla, around the nipples and the groin.
Scabies mites often burrow in the skin between the webs of the fingers. This is one of the first places to look for papules with burrows when a patient presents with a history and symptoms suspicious of scabies.
The mites like to burrow in warm places on the body. Papules and burrows of scabies mites can often be found in the axilla, around the nipples as well as the inguinal and buttock region.
A diagnosis of scabies can often be made based on a detailed history and based on the distribution of the pruritic rash, but a definitive diagnosis can be made by taking skin scrapings and viewing them under a microscope.
Examination of the skin surface with a handheld dermatoscope, or dermoscopy, can allow for visualization of specific structures related to the more superficial layers of the skin.
Using a handheld dermatoscope, eggs and mites can be viewed under magnification.
Topical 5% permethrin cream is one of the most commonly used treatment for scabies. For non-crusted scabies, topical 5% permethrin or oral ivermectin can be used. For crusted scabies, topical 5% permethrin or 5% benzoyl benzoate AND oral ivermectin can be used.
For non-crusted scabies topical 5% permethrin OR oral ivermectin can be used. For crusted scabies, topical 5% permethrin or 5% benzoyl benzoate AND oral ivermectin can be used.
For patients who have failed a safer, first-line treatment, lindane cream can be used. Though lindane cream should only be used for non-crusted lesions, as it is contraindicated in crusted scabies.
In addition to oral medication and creams, it is important to instruct patients to wash all their linens and recently worn clothing in very hot water to kill any mites that are in their bedding or on their clothes.
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