Scabies: An Overview

illustration of scabies mite burrowing through skin
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Scabies is a skin infection caused by the Sarcoptes scabei. Scabies can be a sexually transmitted disease, but it isn't always an STD. Scabies can also be passed between members of a household by skin-to-skin contact, shared clothing, towels, and bedding. This is in contrast to crabs, or pubic lice. Those infections are almost always transmitted sexually,

Scabies mites can live for up to 3 days outside of the human body.

That gives them plenty of opportunities to cause an infection. It's also very difficult for some people to tell when and how they got infected. Symptoms can take up to 4 to 6 weeks to appear after initial exposure. Then, they can last for up to 2 to 3 weeks after treatment. That means that unless someone tells you that they exposed you, it can be very hard to ferret out the evidence.

Symptoms

Scabies causes a skin rash. This rash primarily shows up on folds of skin, such as between the fingers, on the wrists and ankles, and in the genital area. The scabies skin rash makes you incredibly itchy. Another telling sign of scabies is that the itching gets worse at night.

One of the clearest symptoms of scabies is red burrows found between the fingers and on the wrists and ankles. If you think you might be infected with scabies, try not to scratch. Scratching may cause sores. These sores can then get infected by other bacteria and lead to further problems.

The itching caused by scabies is annoying, yes. However, it's much less annoying than dealing with itching and additional infections. That's why it's important to seek out prompt treatment.

Treatment

Several scabies treatments are available that are reasonably effective. These topical treatments help clear up the scabies rash.

They also reduce the risk of more systemic infections. However, there is a growing recognition that better treatments need to be developed. In areas of the world where scabies is common, people often suffer from recurrent infections. These can lead to serious problems, including bacterial infections of the blood (sepsis).

In addition to treating your infection, it's important to treat your home. This includes using special detergents to kill mites on clothing and sheets. Failure to do this increases the risk of re-infection.
Fortunately, although disinfecting your home is annoying, it's relatively straightforward.

Scabies is treated with either topical pesticide creams or an oral medication. The CDC recommends the following treatments:

  • Permethrin 5% cream, applied to all areas of the body from the neck down and washed off after 8-14 hours. This is the only recommended treatment for infants and young children.
  • Ivermectin 200 ug/kg orally, repeated in two weeks. This treatment should not be used in children who weigh less than 15 kg. 
  • Lindane 1% lotion or cream, applied in a thin layer to all areas of the body from the neck down and thoroughly washed off after 8 hours. It should only be used in people who can not tolerate one of the other treatments. This treatment has a risk of toxicity, and resistance to this treatment has also been reported. Lindane should not be used by people with skin problems, and it should not be used directly after a bath or shower. In addition, lindane should not be used for infants and children under the age of 10. 

    Bedding and clothing also needs to be decontaminated and/or removed from body contact for at least 72 hours.

    Did You Know: Scabies is sometimes considered to be a genital ulcer disease. The skin rash it creates may make individuals more susceptible to HIV.

    Sources:

    Mehta B. A clinico-epidemiological study of ulcerative sexually transmitted diseases with human immunodeficiency virus status. Indian J Sex Transm Dis. 2014 Jan;35(1):59-61. doi: 10.4103/0253-7184.132434.

    Thomas J, Peterson GM, Walton SF, Carson CF, Naunton M, Baby KE. Scabies: an ancient global disease with a need for new therapies. BMC Infect Dis. 2015 Jul 1;15:250. doi: 10.1186/s12879-015-0983-z

    Workowski KA, Bolan GA; Centers for Disease Control and Prevention. Sexually transmitted diseases treatment guidelines, 2015. MMWR Recomm Rep. 2015 Jun 5;64(RR-03):1-137. Erratum in: MMWR Recomm Rep. 2015 Aug 28;64(33):924.

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