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 an intensely itchy skin condition. Dermatologists estimate that more than 300 million cases of scabies occur worldwide every year. The mites can infect 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. The microscopic mite that causes scabies can barely be seen by the human eye. The mite burrows in the uppermost layer of the skin and within several weeks, the patient develops an allergic reaction causing severe itching. 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. Attracted to warmth and odor, the female mite burrows into the skin, lays eggs, and produces toxins that cause allergic reactions. 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 after infection before a person will notice the itching.
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, the buttocks or belt line. 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.
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 harbor thousands of live mites and their eggs, making treatment difficult because medications applied directly to the skin may not be able to penetrate the crust. This type of scabies occurs mostly among the elderly, in some AIDS patients, or in people whose immunity is decreased.
To diagnose the infection, your dermatologist will do a thorough examination in good lighting, with careful attention to skin crevices. To confirm scabies your dermatologist can perform a painless test that involves scraping the lesions and transferring them to a glass slide, which is examined under a microscope.
A diagnosis is made by finding scabies mites or their eggs. Treatment of scabies involves one of the following approaches:
- 5% permethrin cream is applied to the skin from the neck down at bedtime and washed off the next morning. A second treatment one week later may be recommended. Lesions heal within four weeks after the treatment.
- 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 which 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.
- Eradicating 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 or reinfection. This may include close friends, day care or school classmates, or nursing homes.
- Wash clothes. 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.
- 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.