Scabies - Topic Overview

What is scabies? Scabies is a condition of very itchy skin caused by tiny mites that burrow into your skin. See a picture ofscabies .

Scabies can affect people of all ages and from all incomes and social levels. Even people who keep themselves very clean can get scabies. How is scabies spread? Scabies mites spread by close contact with someone who has scabies. Scabies can also be spread by sharing towels, bed sheets, and other personal belongings. Scabies often affects several family members at the same time. You can spread it to another person before you have symptoms. What are the symptoms? Scabies causes severe itching that is usually worse at night and a rash with tiny blisters or sores. Small children and older adults tend to have the worst itching. Children typically have worse skin reactions. If this is the first time you have had scabies, it may be several weeks before you have itching and skin sores. But if you have had it before, symptoms will probably start in a few days. How is scabies diagnosed? A doctor will suspect scabies based on your symptoms. Scabies is especially likely if you have had close contact with other people who have had similar symptoms. Sometimes a doctor confirms a diagnosis by looking for signs of mites on a sample of your skin. The doctor gently scrapes some dry skin from an affected area and then looks at it under a microscope. This test is not painful for most people. How is it treated? Scabies will not go away on its own. You need to use a special cream or lotion that a doctor prescribes. In severe cases, your doctor may also give you pills to take. Some scabies medicines are not safe for children, older adults, and women who arepregnant or breastfeeding. To avoid dangerous side effects, be sure to follow your doctors instructions carefully. If you have scabies, you and anyone you have close contact with must all be treated at the same time. This keeps the mites from being passed back and forth from person to person. You must also carefully wash all clothes, towels, and bedding. After treatment, the itching usually lasts another 2 to 4 weeks. It will take your body that long to get over the allergic reaction caused by the mites. If you still have symptoms after 4 weeks, you may need another treatment.

Scabies - Cause
Scabies is caused by the mite Sarcoptes scabiei.Scabies mites are attracted to the warmth and smell of humans. Female mites burrow into the skin, creating small, threadlike tunnels that you can sometimes see. The mites lay eggs and leave feces in these tunnels. How scabies is spread

Scabies usually is spread by close, intimate contact, such as sleeping in the same bed with or touching someone who has scabies. The scabies mite cannot fly or jump, and it moves very slowly. Scabies mites only live for several days away from human skin. During this time, the mites may spread to other people. Mites usually spread through skin-to-skin contact. But they can also spread from contact with clothing, bed linens, and other household and personal items. A mite burrows very quickly under the skin, especially in areas where it is rough or wrinkled, such as the elbows, knuckles, and knees. Touching or scratching an area that is infested with mites can spread them to other parts of the body. After burrowing under the skin, a female mite lays eggs before she dies. The eggs hatch into larvae several days later. These larvae move to the skin's surface and become adults within about 2 weeks. This cycle continues until the mites are killed. The scabies mite that infests humans does not live on dogs or other pets. And animal-transmitted scabies mites do not survive or reproduce on humans. But they can live long enough on humans to cause itchy hives or raised bumps that last a few days. Contagious and incubation periods Scabies is contagious. If you have scabies, you can spread mites to other people before and after you have symptoms, for as long as you remain infested and untreated. After your first infestation, several weeks may pass before you have symptoms. You are contagious during this time, which is known as the incubation period. If you ever become infested with mites again, it will likely take only 2 or 3 days for you to notice symptoms.

Scabies - Symptoms
If you have scabies, you will likely have itching and irritated skin that gets worse until the mites are killed. Itching usually starts first. It often becomes noticeable at night or after bathing and is sometimes mistaken for dry skin. Itching is caused by an allergic reaction to the scabies mite. Sometimes the itching is very intense, especially in small children and older adults. Irritated skin often appears as a rash and skin sores that look like tiny curving tracks. These symptoms are a result of the mite tunneling under the upper layers of the skin. Sometimes you can see a small blister or the mite itself, which looks like a tiny black dot, at the end of a burrow. The tracks may be hard to see after you scratch the area. Babies may only have red and inflamed skin, sometimes with small sores that are like blisters. Symptoms are most likely to develop: Between the fingers and on the palm side of the wrists. On the outside surfaces of the elbows and in the armpits. Around the waistline and navel. On the buttocks. Around the nipples, bra line, and the sides of the breasts (in women). On the genitals (in men). In babies and small children, itching and skin irritation may also occur: Around or on the scalp, neck, and face. On the palms of the hands and soles of the feet. Often the first symptom noticed in a baby is in these areas and is a series of tiny sores that are like blisters (vesicles).

Other problems Skin sores, called secondary lesions, can develop later in the course of the condition. Problems may include: Scratches, sometimes covered by a crust. Scratching the scabies burrows can irritate and break open the skin. Red, dry, scaly, irritated areas of skin. Nodular scabies. These are small reddish brown raised areas (nodules). The nodules may develop in covered areas such as the armpits, groin, buttocks, scrotum, and penis. The nodules itch and may persist for weeks or months after scabies has been cured. Babies and older adults are especially at risk for these lesions, because they may not be treated right away. Early symptoms in babies and older adults are more likely to be missed or mistaken for another condition.

Scabies - What Happens

First-time infestation The first time you are infested with the scabies mite, itching may not begin for several weeks. During this time, you are contagious but may not know that you are carrying scabies mites. In the first few weeks of scabies infestation, the body develops sensitivity to the mites, their eggs, and their feces. After your body has become sensitized, an allergic reaction is triggered, causing itching. With treatment, the scabies mites die and the itching gradually goes away over a period of days to weeks. Usually a doctor will tell you it is safe for your child to return to school after treatment is completed and the medicine has been washed from the skin. Treatment takes 1 to 3 days depending on the medicine used. If all of the scabies eggs are not killed by the first treatment, they may hatch and cause symptoms again. Without treatment, the mites reproduce and cause more sores and more itching. Scabies will not go away on its own. Only animal-transmitted scabies will go away without treatment. Repeat infestation If you have had scabies and are infested with the mites again, itching will begin almost immediately. The allergic sensitivity developed during the previous exposure triggers an immediate reaction to the mites. Treatment is usually required to kill the mites and eggs. In rare cases, a person's allergic reaction will kill the scabies. Complications The most common complication of scabies is a bacterial skin infection, such asimpetigo. This most often occurs when the skin has been scratched raw. Hairfollicles may also become infected (folliculitis). Antibiotics may be needed to treat a bacterial skin infection. The skin can become thick, red, and scaly or shiny from persistent scratching. In rare cases, crusted (Norwegian) scabies, a severe form of scabies, develops. Usually, this type of scabies is most common in people who have weakened immune systems, such as those with HIV. People with crusted scabies may have extreme infestations with tens of thousands of mite. In otherwise healthy people, an infestation is usually limited to about 10 or 15 mites.

Scabies - What Increases Your Risk

The following groups of people are at higher risk of exposure to scabies mites: Sexually active young adults. Close skin-to-skin contact (not specifically sexual intercourse) makes transmission of the scabies mites more likely.

People who live or work in institutions such as nursing homes, homes for the developmentally disabled, and prisons. People who live in crowded conditions. Children from developing countries. People who have weakened immune systems, such as from HIV, and those who are unable to communicate about their physical symptoms are at risk for severe, difficult-to-treat cases of scabies, particularly crusted (Norwegian) scabies.

Scabies - Exams and Tests

Usually, your doctor can diagnose scabies if you have: Severe itching, especially at night. A rash, sometimes with skin sores . These may look like tiny curving tracks. Sometimes you may have a small blister or see a tiny black dot at one end of the track. In babies, the tracks may look more like red and inflamed skin, sometimes with small sores that are like blisters. Your doctor will check your skin for redness, sores, scratches, raw areas, or scabs that are typical of scabiesinfestation. Other family members or people you are physically close with who are also itching or who have recently been diagnosed with scabies. Sometimes you may need one of the following tests to confirm the diagnosis: Skin scrapings. Your doctor collects material from the itchy area by applying a drop of mineral oil or other liquid to the skin and then scraping the area with a scalpel. He or she then examines the scrapings under a microscope to look for scabies mites, eggs, egg casings, or feces. This is the most common test used to diagnose scabies. Needle extraction of the mite. The doctor may use a needle to remove a mite from the burrow. The mite is placed on a slide and examined under a microscope. Ink test or ink burrow test. Your doctor strokes a washable felt-tip pen across the itchy areas. The surface ink is wiped off with water or an alcohol swab. Any burrows present will absorb the ink and be seen as a dark line. Skin biopsy/punch biopsy. A skin sample (punch biopsy or shave biopsy) may be helpful in diagnosing hard-to-diagnose conditions. Skin biopsy is rarely used

Scabies - Treatment Overview

If you suspect that you have scabies, see your doctor as soon as possible for treatment. Delaying treatment increases the risk that the scabies mites will spread to other people. Scabies will not go away on its own. Scabies can only be cured with prescription creams, lotions, or pills. Nonprescription medicines are not strong enough to kill the mites. Most creams or lotions are applied to the entire body from the neck down. On infants, the medicine is also applied to the scalp, face, and neck, taking care to avoid the area around the mouth and eyes. The medicine usually is left on for 8 to 14 hours and then washed off. Children can usually return to day care or school after treatment is completed and the medicine has been washed off. Treatment takes 1 to 3 days depending on the medicine used. In some cases, the doctor may prescribeivermectin pills to treat the scabies. Your doctor may recommend that you be examined 2 weeks and 4 weeks after completing treatment, to ensure that the scabies has cleared up.

Persistent nodular scabies may be treated with injections of steroids into the nodules. In rare cases, coal tar products are applied to the nodules. You will likely continue to itch for days to weeks after the mites are killed. This itching is caused by an ongoing allergic reaction to the mite bites. Your doctor may recommend antihistamines (such as Benadryl), steroid creams, and, in severe cases, steroid pills to help relieve itching. The allergic reaction will usually disappear gradually. Who else should be treated? Anyone who has had close physical contact with a person who is infested with scabies should be treated. This may include several members of the same household, including anyone who has prolonged skin-toskin contact (sleeping, bathing, or holding hands) with the infected person.

Scabies - Prevention
Not having close skin-to-skin contact with someone who has scabies or with their personal items (such as clothes, towels, and brushes) will help you avoid getting scabies. People who have scabies are encouraged to use care to prevent spreading the mites to others.

Scabies - Medications
Prescription permethrin, such as Elimite cream, is the most commonly used medicine to treat scabies. Unlike the more toxic lindane, permethrin is considered safe for infants as young as 2 months old. Only permethrin, crotamiton, and sulfur ointment are considered safe for treating children younger than age 2. Lindane may be used in some cases if other treatments don't work. But it must be used exactly as your doctor says, because in rare cases this medicine can cause seizures and death when it isn't used according to directions. In some cases, the doctor may prescribeivermectin pills to treat scabies. Crusted (Norwegian) scabies (rare) often requires multiple treatments, sometimes with more than one medicine. Steroid creams, antihistamines (such as Benadryl), and, in severe cases, steroid pills can be used to relieve itching. But they do not kill scabies mites. Don't giveantihistamines to your child unless you've checked with the doctor first. Persistent nodular scabies may be treated with injections of steroids into the nodules or (rarely) with coal tar products applied to the skin. Most creams or lotions are applied to the entire body from the neck down. On infants, the medicine is also applied to the scalp, face, and neck, taking care to avoid the area around the mouth and eyes. The medicine usually is left on for 8 to 14 hours and then washed off. Nonprescription medicines are not strong enough to kill the scabies mites Medication Choices Prescription medicines used to treat scabies include: Permethrin cream 5% (Elimite), a standard first treatment for scabies. It usually cures scabies infestation after the first application. Ivermectin, which comes as pills. In the United States, treating scabies with ivermectin is an unlabeled use of the medicine. Ivermectin does not work as well as permethrin but is effective against scabies mites.3 Lindane 1%, which must be used exactly as directed to avoid dangerous side effects. Lindane is only used if your scabies persists after trying other medicines or you are unable to use other treatments. 4 .

Sulfur ointment (precipitated sulfur) 5% to 10%, a milder and less effective medicine than permethrin or lindane, is sometimes used to treat infants andpregnant or breast-feeding women. Crotamiton 10% (Eurax), which is not often used to treat scabies because it does not dependably kill all the mites and their eggs. You may also need to take an antibiotic if you get a secondary skin infection. What To Think About When used correctly, lindane is considered a safe and effective treatment for scabies. With incorrect use or overuse, though, lindane can be dangerous and can permanently damage the central nervous system. If your doctor prescribes lindane to treat scabies, make sure you receive, understand, and follow detailed instructions for using it correctly. Scabies treatment can fail:

When the medicine is not applied properly. Carefully follow instructions for using scabies medicines. If the medicine does not kill the scabies eggs. When the eggs hatch, a new infestation begins. When other members of the affected person's household are not treated.