Scabies
Definition
Scabies is an infestation of the skin. It is most commonly caused by a tiny mite.
Scabies

Causes
An infestation results when the female mite burrows into the skin and lays its eggs. The scabies mite does not suck blood. It does not transmit any disease other than scabies between people.
Scabies is highly contagious. Most often, it is passed from person to person through:
- Close and generally prolonged physical contact
- Sexual contact
Scabies can also spread from person to person by sharing:
- Clothing
- Towels
- Bedding
Scabies can occasionally also be acquired from certain mammals. It is most common from dogs with sarcoptic mange. Scabies from dogs differs somewhat from human scabies. It rarely passes from person to person.
Risk Factors
Factors that increase your chance of scabies include:
- Age: less than 15 years, or older than 65 years
- Sexual contact with new or multiple partners
- Close, physical contact with a person who has scabies
- Living in close quarters with others (such as in a nursing home or military barracks)
- A weakened immune system
- Close contact with animal scabies
Symptoms
Symptoms of scabies include:
- Intense itching, usually worse at night
- Small red bumps, pimples, or lines on the skin
In more severe cases, the infested area may:
- Appear crusty
- Become infected and discharge pus
Scabies rarely affects the face or head. While any other body area, or even the whole body, may be involved, areas most often affected include:
- Hands, especially between the fingers
- Wrists and elbows
- Feet
- Genitals and pubic area (especially in men)
- Buttocks
- Around the nipples (especially in women)
- Waistline
- Bellybutton and lower abdomen
- Areas where clothing is tight
- Under rings, watches, or jewelry
Diagnosis
The doctor will ask about symptoms and medical history. A physical exam will be done. While scabies can often be diagnosed based on these steps, the doctor may scrape some skin off. The sample is examined under a microscope to confirm the diagnosis.
Treatment
It is essential to remove scabies from the living environment to avoid re-infestation after treatment. All bedding and clothing must be thoroughly laundered. Other members of the household or institution ought to be treated.
Permethrin cream 5%
Scabies is usually treated by applying permethrin cream 5%. It is applied to the skin from the neck down. The cream is left on for 8-12 hours. Excessive use of this medication can be harmful. Carefully read and follow the directions. Do not repeat treatments unless told to do so by a doctor.
If new, itchy bumps continue to appear in the days following your treatment, be sure to alert your doctor.
Itch Relief
It may take several weeks for itching to disappear following successful treatment. Itching can be temporarily relieved with:
- Antihistamine
- Corticosteroid cream
- Antihistamines and corticosteroids
Alternative Medications
Some severe cases may respond poorly to other treatments. In this case, an oral medication, called ivermectin , is sometimes prescribed. It is given as a single dose.
Alternative topical creams include crotamiton 10% and lindane 1%.
Lindane is a second line treatment. It should only be given to patients who are unable to take other medications or who have not responded to them. Lindane can be toxic. It should not be overused. Follow the directions as given.
Prevention
To reduce your risk of getting scabies, avoid close physical contact with anyone who has either scabies or an undiagnosed itchy rash and do not share their:
- Clothing
- Towels
- Bedding
To prevent the spread of scabies from one person to another:
- Those who share living quarters with an infected person should be considered for treatment.
- Wash or dry clean all clothing, bedding, and towels that may have become infested. Mites may live for at least 2-5 days after they leave a human body. They are probably infectious during some or all of that time.
RESOURCES:
The American Academy of Dermatology
http://www.aad.org/
Familydoctor.org, American Academy of Family Physicians
http://familydoctor.org/
CANADIAN RESOURCES
Communicable Disease Control (CDC) Network
Province of Manitoba
http://www.gov.mb.ca/
Health Canada
http://www.hc-sc.gc.ca/
References:
AHFS Drug Information website. Available at: http://www.ashp.org/ahfs/index.cfm .
American Academy of Dermatology website. Available at: http://www.aad.org .
Lindane shampoo and lindane lotion. Center for Drug Evaluation and Research. US Food and Drug Administration website. Available at: http://www.fda.gov/cder/drug/infopage/lindane/default.htm . Accessed March 12, 2007.
Medical Diagnosis and Treatment . 44th ed. 2005.
Medication guide lindane (LIHN-dane) lotion USP, 1%. Center for Drug Evaluation and Research. Food and Drug Administration website. Available at: http://www.fda.gov/cder/drug/infopage/lindane/lindaneLotionGuide.htm . Accessed March 12, 2007.
Medication guide lindane (LIHN-dane) shampoo USP, 1%. Center for Drug Evaluation and Research. Food and Drug Administration website. Available at: http://www.fda.gov/cder/drug/infopage/lindane/lindaneShampooGuide.htm . Accessed March 12, 2007.
The Merck Manual of Medical Information—Home Edition . Simon and Schuster, Inc; 2000.
National Institute of Allergy and Infectious Diseases website. Available at: http://www3.niaid.nih.gov/ .
Revised lindane lotion label. Center for Drug Evaluation and Research. Food and Drug Administration website. Available at: http://www.fda.gov/cder/foi/label/2003/006309lotionlbl.pdf . Accessed March 12, 2007.
Revised lindane shampoo label. Center for Drug Evaluation and Research. Food and Drug Administration website. Available at: http://www.fda.gov/cder/foi/label/2003/006309shampoolbl.pdf . Accessed March 12, 2007.
Hu S, Bigby M. Treating scabies: results from an updated Cochrane review. Arch Dermatol. 2008 Dec;144(12):1638-40
Last reviewed January 2009 by Ross Zeltser, MD
Please be aware that this information is provided to supplement the care provided by your physician. It is neither intended nor implied to be a substitute for professional medical advice. CALL YOUR HEALTHCARE PROVIDER IMMEDIATELY IF YOU THINK YOU MAY HAVE A MEDICAL EMERGENCY. Always seek the advice of your physician or other qualified health provider prior to starting any new treatment or with any questions you may have regarding a medical condition.
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