Scabies is an infestation with microscopic mites called Sarcoptes scabei, eight-legged creatures that burrow under the skin and cause intense itching. You can pick up scabies by prolonged contact with a person already infested - children get them from other kids, sexual partners from each other. Scabies spread most readily when people are crowded together, in hospitals, childcare facilities, nursing homes and other institutions. You cannot get scabies from pets, because animals attract types of mites that don't survive on the human body.
Symptoms are pretty obvious - beside the itching (which usually is worse at night), there are hive-like bumps on the skin that tend to show up first between the fingers, on the elbows, wrists, buttocks, or waist. The mites can also get under your fingernails or around the skin near watchbands or rings. They can live for up to a month on the human body, but can't survive for more than 48-72 hours elsewhere.
Conventional medicine treats scabies with permethrin, lindane (Kwell lotion) or malathion, all potent insecticides available only by prescription. Some of these (especially lindane) may cause dizziness or seizures in children.
Instead of relying on these toxic treatments, I would recommend using neem, a natural, nontoxic pesticide made from Azadirachta indica, an Indian tree. Neem products are available at health food stores and on the Internet; make sure they are intended for medicinal, not cosmetic use. Antihistamines are usually recommended to relieve itching, but instead, you can try applying counterirritant ointments or creams such as Bengay from the drugstore or the Chinese herbal remedy Tiger Balm, which you can get at many health-food stores.
If one member of the family has scabies, everyone else in the household and any other close contacts should be treated (including staff at childcare facilities). To avoid re-infestation, wash all clothing, linens and towels in hot water and dry in a dryer, not on a clothes-line. Vacuum the whole house carefully and then throw out the vacuum cleaner bag to prevent any mites from escaping into the house.
Elimination of scabies under the skin is usually straightforward, although itching can persist for two to three weeks after treatment. It is, however, all too easy to be re-infested if you don't avoid the conditions that led to your first episode, or do not adequately rid your environment of them. See a dermatologist if scabies keeps recurring or doesn't respond to treatment.
Andrew Weil, M.D.