Scabies

What is it?

Scabies is a skin disease that can be spread from person to person.

What causes it?

Scabies is a skin disease that is caused by a small mite known as Sarcoptes scabiei var. hominis, about the size of a pinhead. The mite can live off a host only 24-36 hours in typical conditions, longer in cooler temperatures and high humidity. It burrows into the outer layer of skin and lays eggs, which hatch in 3-5 days. After hatching, the newly formed mites leave the burrow and move to other skin surfaces and repeat the cycle. Scabies is not caused by being dirty

Is it contagious?

Yes. Scabies is highly contagious and is spread by skin-to-skin contact with a person who has the disease. Contaminated articles such as clothing and bedding can be the source of infection. Although cats and dogs can also contract scabies, in animals the disease is caused by a different sub-species of mite. Transmission from animals to humans is rare and unlikely to cause infestation in humans; however, any animal(s) living with infected humans should receive treatment.

What are its symptoms?

The most common symptoms are severe itching and grayish-white, brown, or pink lines or tracks that zigzag on the skin surface. In some cases, there are nodules (bumps) on the buttocks, genitals or armpits. There may be crusting of the lesions. Areas of the body most commonly affected are the sides of the fingers, webs between the fingers, wrists, elbows, armpits, buttocks, nipples, genitals, knees and feet. A person never before infested with scabies may not develop symptoms for a month or more. A previously infested person will develop symptoms within 24 hours. The intense itching, which is usually most severe at night, is caused by a local allergic reaction to the mites’ saliva. Itching is worse at night because this is when the mites feed. There may be signs of skin infection like redness, swelling or pus, caused by scratching around the mites’ burrows.

How long will it last?

The mites should be completely eliminated after one course of treatment. Itching may continue after treatment, but should subside gradually over a period of several weeks. It should be noted that excessive use of the treatment medication can cause a skin rash and intensify itching. To prevent complications, follow the medication instructions and recommendations carefully.

What treatment can your health provider offer?

Your health care provider can prescribe medication to destroy the mites and to relieve itching. Permethrin (Elimite™) Creme is most commonly used. Another medication, Eurax™, is available for use with pregnant women and children under age three. Ivermectin, an oral medication, is also used, alone or in combination with Permethrin. An older medication, Kwell (Lindane™), is not currently recommended, especially for young children.

What can I do if I am infected?

Proper use of the prescribed medication is of utmost importance in eliminating scabies. Before applying creme medication, take a warm bath or shower using lots of soap to clean the skin. This will help soften the lesions. Pat dry and allow skin to cool. Then, apply the medication in a thin layer from the scalp downward over the entire skin surface, giving special attention to hands, feet and fingers, umbilicus and areas under nails. All areas of the skin must be covered adequately. If the face is involved, be careful not to get medication in the eyes, nose or mouth. If the hands are washed, reapply creme to that area. Keep the medication on for 12 hours and then bathe. All family members and sexual contacts should be treated at the same time.

Keep medication in a safe place, out of reach of children. Follow oral medication (Ivermectin) dosing instructions. Do not take creme medications for scabies by mouth.

On the morning after treatment, wash all clothes, underwear and bedding in hot water and iron or dry in the clothes dryer to eliminate any further spread of the mites. If items are not washable, they may be dry-cleaned or kept in tightly closed plastic bags for several days. Vacuum carpets and upholstery.

It is not necessary to fumigate or exterminate the entire house.

Follow up

Follow up with your health care provider is not necessary after treatment unless symptoms continue for more than a period of two weeks. If symptoms persist, you may call for an appointment.

Remember to call the Dial-A-Nurse if:

References

Cecil's Textbook of Medicine 21st ed. (2000)
Goldstein, B. G., & Goldstein, A. O. Scabies. UpToDate. August, 2006.