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Scabies is a contagious skin infestation caused by tiny mites.
The microscopic, 8-legged human itch mite digs into the skin to feed and lay eggs; however, it cannot survive outside human skin for more than 2 to 3 days. Scabies is transmitted by direct person-to-person contact or through objects that carry the mites, such as clothing and bedding. Scabies can affect anyone but is most common in children and crowded populations, such as jails, refugee camps, and nursing homes. Because scabies is a human parasite, household pets are typically not affected. Most people with scabies have fewer than 100 mites. However, the itching and rash can be everywhere.
Norwegian scabies, or crusted scabies, is a severe infestation of hundreds to thousands of mites that appears as a thick, yellow-gray crust on the skin. It occurs in elderly people or those with disabilities who cannot scratch or feel the itch. It also occurs in those with weakened immune systems.
Signs and Symptoms
Intense, itchy rash that worsens at night
The rash usually consists of tiny, raised bumps arranged in a line where the mites burrow under the skin to lay eggs. The rash can also resemble pimples, eczema, and insect bites.
Scabies commonly live between the fingers and toes, under jewelry or watches on the wrist, and in armpits, skin folds, and genitalia.
Infants with scabies may appear irritable, not wanting to eat or sleep, and commonly have the rash on their palms or the soles of their feet. Infants can also have the rash on their face, scalp, and neck, which is rare in adults.
Symptoms can take 2 to 6 weeks to appear after infestation. People can be contagious even when they do not have symptoms.
Diagnosis and Treatment
A doctor examines the skin and rash to make a diagnosis and may take a scraping of skin to look for microscopic evidence of mites.
Treatment requires killing the mites living on the body with a prescribed cream or oral pills. No over-the-counter treatment is available for scabies.
The most commonly prescribed cream is permethrin, 5%, which is applied from neck to toes, left on for 8 to 14 hours, washed off, and reapplied 1 week later.
Crusted scabies requires multiple treatments of oral and topical medications as directed by a doctor.
Household pets do not need to be treated.
Itching can be relieved with lotions, antihistamines, and corticosteroids, but these do not kill the mites.
Itching and the rash may remain for up to 4 weeks after treatment despite killing all the mites.
Because scabies is highly contagious, children must be kept out of school until they complete treatment.
All people living in the same household, sexual partners, and others who have had close skin-to-skin contact with the affected person need to be treated. Heat kills mites and their eggs, so it is important to wash all bedding, clothes, and towels in hot water and dry them in high heat each time treatment is administered.
Centers for Disease Control and Preventionwww.cdc.gov/parasites/scabies/index.html
American Academy of Dermatologywww.aad.org/public/diseases/contagious-skin-diseases/scabies
Conflict of Interest Disclosures: All authors have completed and submitted the ICMJE Form for Disclosure of Potential Conflicts of Interest and none were reported.
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Tarbox M, Walker K, Tan M. Scabies. JAMA. 2018;320(6):612. doi:10.1001/jama.2018.7480
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