Scabies: causes and treatment

How Scabies Develops
What to Look For
Crusted Scabies (Norwegian)
Diagnosing Scabies
Who Is at Risk?
Getting Rid of Scabies

Scabies is caused by a tiny mite that has infested humans for at least 2,500 years. It is often hard to detect and causes a fiercely itchy skin condition.

Dermatologists estimate that more than 300 million cases of scabies occur worldwide every year. The condition can strike anyone of any race or age, regardless of personal hygiene. The good news is that with better detection methods and treatments, scabies does not need to cause more than temporary distress.

How Scabies Develops

The microscopic mite that causes scabies can barely be seen by the human eye. Being a tiny, eight-legged creature with a round body, the mite burrows in the skin. Within several weeks, the patient develops an allergic reaction causing severe itching that is often intense enough to keep sufferers awake all night.

Human scabies is almost always caught from another person by close contact. It could be a child, a friend, or another family member. Everyone is susceptible. Scabies is not a condition only of low-income families and neglected children, although it is more often seen in crowded living conditions with poor hygiene.

Attracted to warmth and odor, the female mite burrows into the skin, lays eggs, and produces toxins that cause allergic reactions. Larvae, or newly hatched mites, travel to the skin surface, lying in shallow pockets where they will develop into adult mites.

If the mite is scratched off the skin, it can live in bedding for up to 24 hours or more. It may take up to a month before a person will notice the itching, especially in people with good hygiene and who bathe regularly.

What to Look For

The earliest and most common symptom of scabies is itching, especially at night. Little red bumps like hives, tiny bites, or pimples appear. In more advanced cases, the skin may be crusty or scaly.

Scabies prefers warmer sites on the skin such as skin folds, where clothing is tight; between the fingers or under the nails; on the elbows or wrists; on the buttocks or belt line; around the nipples; and on the penis.

Mites also tend to hide in or on bracelets and watchbands, or the skin under rings. In children, the infestation may involve the entire body including the palms, soles, and scalp. The child may be tired and irritable because of loss of sleep from itching or scratching all night.

Bacterial infection may occur due to scratching. In many cases, children are treated because of infected skin lesions rather than for the scabies itself. Although treatment of bacterial infections may provide relief, recurrence is almost certain if the scabies infection itself is not treated.

Crusted Scabies (Norwegian)

Crusted scabies is a form of the disease in which the symptoms are far more severe. Large areas of the body, like the hands and feet, may be scaly and crusted. These crusts hide thousands of live mites and their eggs, making treatment difficult because medications applied directly to the skin may not be able to penetrate the thickened skin.

This type of scabies occurs mostly among the elderly, in some AIDS patients, or in people whose immunity is decreased. It is extremely infectious.

Diagnosing Scabies

Your Water’s Edge Dermatology practitioner will do a thorough head-to-toe examination in good lighting, with careful attention to skin crevices.

Many cases of scabies can be diagnosed by your Water’s Edge Dermatology practitioner without special tests. To confirm scabies your Water’s Edge Dermatology practitioner can perform a painless test that involves applying a drop of oil to the suspected lesion. The site is then scraped and transferred to a glass slide, which is examined under a microscope. A diagnosis is made by finding scabies mites or their eggs.

Who Is at Risk?

Scabies is most common in those who have close physical contact with others, particularly children, mothers of young children, sexually active young adults, and elderly people in nursing homes.

Scabies among resident patients of nursing homes and extended care facilities has become a common problem due to delayed diagnosis since it can be mistaken for other skin conditions. The delay allows time for scabies to spread to nursing home staff and other residents. Because residents require assistance in daily living activities, this exposure provides an opportunity for the scabies to spread.

Getting Rid of Scabies

The most common treatment for scabies is 5% permethrin cream. It should be applied to the skin from the neck down at bedtime and washed off the next morning. Dermatologists recommend that the cream be applied to cool, dry skin over the entire body (including the palms of the hands, under fingernails, soles of the feet, and the groin) and left on for 8 to 14 hours. A second treatment one week later may be recommended.

While it is safe for children as young as one month old as well as pregnant women, side effects include mild temporary burning and stinging. Lesions heal within four weeks after the treatment. If a patient continues to have trouble, re-infestation may be a problem requiring further evaluation by the Water’s Edge Dermatology practitioner. Other treatments may include:

1% lindane lotion is applied from the neck down at night and washed off in the morning. It may be reapplied one week later. Lindane should not be used on infants, small children, pregnant or nursing women, or people with seizures or other neurological diseases, and has been banned in the state of California.
10% percent sulfur ointment and crotamiton cream may be used for infants.
Ivermectin is an oral medicine that may be prescribed for the difficult to treat crusted form. It is not to be used in infants or pregnant women.
Antihistamines may be prescribed to relieve itching, which can last for weeks, even after the mite is gone.

Getting rid of the mites is critical in the treatment of scabies. Everyone in the family or group, whether itching or not, should be treated at the same time to stop the spread of scabies. This includes close friends, day care or school classmates, or nursing homes.

Successful eradication of this infestation requires the following:

See a Water’s Edge Dermatology provider as soon as possible to begin treatment. Remember, although you may be disturbed at the thought of bugs, scabies is no reflection on your personal cleanliness.
Treat all exposed individuals whether obviously infested or not. Incubation time is six to eight weeks so symptoms may not show up for a while. If you do not treat everyone, it is as if you were never treated.
Apply treatment to all skin from neck to legs. This includes between toes, the crease between the buttocks, etc. If you wash your hands after application, you need to reapply the medication to your hands again.
Wash clothes and bedding. Do all the laundry with the hottest water possible. The mite is attracted to scent. Any clean clothes hanging in the closet or folded in the drawers are OK. Items you do not wish to wash may be placed in the dryer on the hot cycle for 30 minutes, or pressed with a warm iron.
Items may be dry-cleaned.
Change the bedding.
Carpets or upholstery should be vacuumed through the heavy traffic areas. Vacuum the entire house and discard the bag, just to be on the safe side.
Pets do not need to be treated.
Items may also be placed in a sealed plastic bag and placed in the garage for two weeks. If the mites do not get a meal within one week, they die.