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Scabies

Itchy Skin Rash

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Updated January 21, 2014

Scabies is a very itchy rash caused by the mite, Sarcoptes scabiei. Scabies occurs in both sexes, all ages, and all ethnic groups. In fact, it's estimated that at least 300 million cases of scabies occur worldwide every year.

What Causes Scabies

The mite that causes scabies is tiny, often too small to be seen with the naked eye. The female mite burrows under the skin and lays 10 to 25 eggs before she dies. The eggs hatch three days later and the larvae move to the surface of the skin. The larvae mature into adults in 10 to 14 days.

How Scabies Is Spread

Scabies is spread by direct skin-to-skin contact. Contact with infested bedding or clothes only rarely causes a new infection.

Scabies Appearance

The rash of scabies can often look similar to other rashes. The rash causes red papules with small lines attached called burrows. However, the mite doesn't usually travel far once its under the skin, so the burrows may not be visible. A scabies rash typically occurs on the wrists, in between fingers, in the armpits, around the waist, and in the genital area. The rash causes intense inflammation in the skin with blisters, redness, and itching.

Scabies Diagnosis

Scabies is usually diagnosed when the the appearance and location of the rash fits the symptoms above. A rash is more likely to be scabies if a family member has a similar rash. There are no good tests that can diagnose scabies. Some textbooks suggest scraping off a small portion of the rash and looking at it under a microscope for mites, but the mite is rarely found with this test.

Scabies Treatment

The following are treatment options to get rid of scabies:
  • Permethrin 5% cream - Apply liberally from the top of the neck to the soles of the feet at bedtime and rinse off in the morning. Permethrin is the safest treatment for pregnant women.
  • Lindane 1% lotion - Apply a thin layer from the top of the neck to the soles of the feet at bedtime and rinse off in the morning. Lindane should not be used by pregnant women.
  • Ivermectin is an oral medication used to treat other parasites. The dose used is based on the weight of the person taking the medicine and it is taken in 2 doses, 2 weeks apart. It is currently not approved by the FDA for treatment of scabies, but there are studies that show that it is effective.

Treatment of Itching

Using the above medications kills the mites but they are still present in the skin until the body breaks them down and absorbs them. This process can take about 4 weeks and it is common for the rash to be very itchy for the entire month. Topical steroids applied to particularly itchy spots and oral antihistamines like Benadryl may help relieve itching.

Treatment for Loved Ones

People who have close contact with someone diagnosed with scabies also should be treated. "Close contact" includes sexual partners and anyone who has had prolonged, skin-to-skin contact with someone with scabies. Giving someone a quick hug or a handshake does not put them at risk. Often entire households are treated even if only one person has symptoms. If your healthcare provider recommends treating your family, all family members should receive treatment at the same time.

Clothing and Bedding

All clothes, bedding, and towels used by the person with scabies up to two days before treatment should be washed in hot water and dried in a hot dryer.

Sources:

Chosidow, Olivier. "Scabies." The New England Journal of Medicine 354(2006): 1718-27.

Flinders, David, and Peter De Schweinitz. "Pediculosis and Scabies." American Family Physcian 69(2004): 349-50.

Heukelbach, Jorg, and Hermann Feldmeier. "Scabies." The Lancet 367(2006): 1767-74.

Johnston, Graham, and Mike Sladden. "Scabies: Diagnosis and Treatment." British Medical Journal 331(2005): 619-22.

"Scabies Fact Sheet." CDC. 10 Feb 2005. 19 Aug 2007.

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