Lice, Scabies, and Your Skin

Lice and scabies are highly contagious skin conditions that involve parasites living on or in the skin.

Lice

Lice are small, grayish-brown insects that live on humans. Lice bite through the skin and live on the blood of the host, another name for the infected person. Female lice lay eggs -- called nits -- that firmly attach to hair shafts. Head lice live on the scalp and are common among school children. Lice also can be found on the body (body lice) or in the pubic region (pubic lice).

Head lice are spread by direct head to head contact and by sharing items including combs, brushes, scarves, and hats with an infected person. Pubic lice (crabs) are spread by having close physical contact with someone who has them. They are most often spread by sexual contact, but they can also be spread by having contact with infested clothing, bed linens, and toilet seats.

Lice infestation has nothing to do with poor hygiene. Lice can also affect people of all social classes.

What Are the Symptoms of Lice?

Bites from lice can cause intense itching and irritation of the scalp or other area of the body where lice are present. Symptoms may not occur until at least two months after the lice begin living on the body. In cases of head lice, a person may develop a rash on the nape of the neck.

What Is the Treatment for Lice?

Insecticides can be used to treat head lice by killing them. These products are available in lotion and shampoo form and can be purchased over-the-counter or with a prescription. Some studies suggest that pyrethroid insecticides (such as allethrin, resmethrin, permethrin, cyfluthrin, or esfenvalerate) can affect cognitive development in children. More research is needed.

Lice eggs (nits) can be more difficult to treat because the insecticide lotions do not penetrate the eggshell to get in to the developing louse. Therefore, it may be necessary to repeat the treatment after seven days to kill lice emerging from any eggs that survived the first application. Using a nit comb can help to get rid of nits.

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Another treatment is a topical lotion called Sklice. A comb is not required with Sklice and one treatment may be all that's needed. The active ingredient is ivermectin, a powerful parasite killer. Sklice can be used in kids as young as 6 months.

Pubic lice are treated by washing the infested area with a special shampoo. Shampoos that kill lice (such as RID and A-200) are available without a prescription. Follow the directions on the bottle.

How Can Lice Be Prevented?

The best way to prevent lice is to avoid sharing combs, brushes, towels, scarves, hats, clothes, and other objects. Avoid close physical contact with someone who has lice. Examine and treat all members of your household who have had contact with someone who has lice.

If you find that your child has lice, notify your child's school, day care center, or babysitter. It is important to wash all combs, brushes, hats, and towels after each shampoo if anyone in your family has lice. You must also wash clothes, bed linens, and towels in the hot cycles of your washer and dryer. (Heat kills the insects.) It is not necessary to spray clothes or household objects with an insecticide.

Scabies

Scabies is an itchy skin condition caused by a microscopic mite called Sarcoptes scabei. The mite burrows into the skin. Within several weeks of the time the mite burrows, an allergic reaction occurs and severe itching begins.

The condition can affect people of any social class and everyone is susceptible. However, scabies occurs more often in situations involving crowded living conditions with poor hygiene.

How Does a Person Get Scabies?

In most cases, scabies develops after close, prolonged contact with another person. Scabies can easily be spread between sexual partners and household members. Scabies-causing mites can be scratched off the skin and can cause an infestation in another person. Infestation may also occur by sharing clothing, towels, and bedding -- mites can live in bedding for up to 24 hours or more.

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What Are the Symptoms of Scabies?

The primary symptom of scabies is severe itching, which often is so bad that it keeps people awake at night. The itching is caused as the female mite burrows into the skin, lays eggs, and produces toxins that cause allergic reactions. Small red bumps (resembling tiny bites or pimples) can form on the skin.

The most common areas for scabies to develop on the body are warmer sites such as skin folds, areas where clothing is tight (such as the belt line or buttocks), on the penis, and around the nipples.

Excessive scratching may lead to bacterial infections of the skin in people who have scabies.

How Is Scabies Diagnosed?

A doctor can look at the rash on your skin to determine whether you have scabies. A skin scraping may be taken to look for mites, eggs, or mite fecal matter to confirm the diagnosis.

How Is Scabies Treated?

Scabies is treated with a lotion that is applied to a clean body from the neck down to the toes. The lotion is left on overnight (8 hours) and then is washed off. The person with scabies should put on clean clothes. All clothing, bedding, and towels used by the person in the preceding 24 hours should be washed in hot water and dried in a hot dryer. Seven to 10 days after the first treatment, a second treatment of the body with the same lotion is usually given. Medication may be prescribed to relieve itching. Although itching may continue for two to three weeks, the itching does not mean that the infestation is still active. About 24-48 hours after effective treatment, no new burrows or rashes should appear.

Another option is a pill, ivermectin, which is as effective as the creams in eliminating the infestation without the mess. The medication is given twice over a week to 10-day period.

Anyone who is diagnosed with scabies should be treated. In addition, that person's sexual partners of the past month and those persons who have close, prolonged contact to the infested person should also be treated. If all family members need to be treated, everyone should receive treatment at the same time to prevent reinfestation.

 

WebMD Medical Reference Reviewed by Hansa D. Bhargava, MD on July 22, 2015

Sources

SOURCE:

News release, Sanofi Pasteur U.S.

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