Scabies

Scabies is a skin disease caused by a microscopic mite called Sarcoptes scabiei var. hominis. The female mite burrows into the upper layer of the skin, where it lays its eggs. The body's immune response to the mite, its eggs, and its feces causes the primary symptom: intense itching.

The disease occurs worldwide, particularly in crowded settings such as overcrowded housing, refugee camps, prisons, and care facilities. The World Health Organization has listed scabies among neglected tropical diseases, meaning that treatment and research receive limited resources despite affecting large numbers of people.

Transmission

Transmission most commonly occurs through prolonged skin-to-skin contact, such as among people who sleep together or within families, and through sexual contact. Clothing, bedding, and towels can occasionally carry the mite, as it can survive outside the body for hours to several days. Following first exposure, itching can begin one to two weeks later, since the immune response takes time to develop; in people previously infected, symptoms appear rapidly.

Symptoms

The most common symptoms are itching that worsens at night and small red bumps or burrows visible on the skin. Frequently affected areas include the spaces between fingers, wrists, armpits, abdomen, genitals, and buttocks. In young children and infants, the head, neck, feet, and soles can also be affected. Persistent scratching can break the skin, creating an entry point for bacterial infection.

Crusted scabies

Crusted scabies, also known as Norwegian scabies, occurs in people with weakened immune systems or reduced skin sensation. Large numbers of mites inhabit the skin, which becomes thick and scaly, and itching may sometimes be minimal. This form spreads easily and typically requires combination treatment and strict hygiene measures.

Diagnosis and treatment

Diagnosis is usually based on examination of the skin and symptom history, especially if household members are similarly affected. A skin scraping for microscopic examination or dermoscopy can also be used. Treatment involves topical medications such as permethrin and oral medications such as ivermectin; some countries use sulfur, particularly for children and pregnant women. It is important to treat all household members simultaneously, including those without symptoms, and to wash clothing and bedding in hot water or isolate it for several days.