Scabies
Scabies is a skin infestation caused by the human scabies mite, Sarcoptes scabiei, an arachnid that burrows into the upper layer of the skin, leading to intense itching and a red rash. The infestation is characterized by severe pruritus, often localized to areas such as the fingers and hands, but it can affect nearly any skin surface. The life cycle of the mite lasts about three to four weeks, and a typical infected individual may harbor around eleven adult female mites. In some cases, particularly among the elderly or immunocompromised, a more severe form known as Norwegian scabies can occur, with individuals housing millions of mites.
Diagnosis typically involves a skin examination to identify burrows and may include skin scrapings for microscopic analysis. Effective treatment consists of washing clothing and bedding in hot water, sealing non-washable items in plastic, and applying topical treatments like permethrin or lindane. Oral ivermectin can also be used for more challenging cases. Prompt diagnosis and treatment are crucial to prevent the spread of scabies to others, making awareness and understanding of the condition essential for effective management.
Scabies
ANATOMY OR SYSTEM AFFECTED: Skin
DEFINITION: Skin infestation by mites, causing a rash and severe itching
CAUSES: Skin infestation by mites
SYMPTOMS: Rash, severe itching
DURATION: Several days to weeks
TREATMENTS: Washing clothing and bed linen in hot water, sealing nonwashable items in plastic for a week, overnight application of permethrin or lindane
Causes and Symptoms
The human scabies mite Sarcoptes scabiei, a small arachnid, approximately 0.4 millimeter long, produces intense pruritus (itching) and a red rash. Though scabies is most commonly noted on the fingers and hands, almost any skin surface can be affected. After fertilization, the female mite burrows into the upper layer of the host’s skin and deposits several eggs. Upon hatching, the young migrate to the surface, where they mature; this life cycle lasts three to four weeks. In most cases, an affected human host will have an average of eleven adult females. The elderly and patients are susceptible to a more severe, widespread variant called Norwegian scabies. In cases of Norwegian scabies, a human host may carry more than two million adult females.
A patient with scabies generally complains of severe itching, and the skin may be inflamed from scratching. Examination with a magnifying lens reveals characteristic burrows several millimeters in length, especially in the spaces between the fingers. A skin scraping aids in the diagnosis, producing a specimen for microscopic viewing which reveals the adult mite, eggs, or feces.
Treatment and Therapy
The treatment of scabies is straightforward. Clothing and bed linen should be washed in hot water. Shoes or other articles that cannot be washed may be sealed in a plastic bag for a week; this kills the mites, which need a human host to survive for more than a few days. Patients are treated with a 5 percent preparation of permethrin applied from head to foot (sparing the mouth and eyes) and left on overnight. An alternative treatment is lindane, which is less commonly used because of the risk of nerve toxicity in children. With either treatment, the medication is rinsed off in the morning shower. A single dose of oral ivermectin may be used alone or in combination with topical agents to treat difficult cases. Rapid diagnosis and treatment decrease the chance of the mites spreading to other individuals.
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