Scabies is a disease, or an infestation, caused by a nearly invisible creature: Sacoptei scabies, better known as the "itch mite." The mite prefers to attack the thin-skinned regions of the body, those that are relatively free of hair and oil glands. Individuals of all ages and races are potential targets, and at present scabies is epidemic in the United States. Since it is spread through intimate body contact, scabies is currently one of the more prevalent sexually transmitted diseases and is especially common in persons under thirty.
The female itch mite, which burrows her home within her victim's skin, is the source of the problem. Linear zigzag burrows in which the female lays her eggs may range is size from one-eighth of an inch to several inches in length. As the organisms multiply and spread through the skin, small, pimplelike spots and tiny blisters or pustules begin to appear. Later, following an incubation period of about four to six weeks, a widespread rash covering large parts of the body may appear; it is intensely itchy, particularly at night. Scratch marks, crusting, and even infection may complicate the appearance of the rash. The eruption, which is believed to be allergic in nature, can be especially severe in individuals with a background of atopic dermatitis. (A less common variant, known as nodular scabies, in which thick, brownish red nodules form in the armpits, groin, buttocks, genital region, and shoulders, is also believed to have an allergic basis.)
Scabies is a highly contagious condition and usually spreads from one individual to another by direct contact. Even a simple handshake has been known to transfer the mite. It can also be spread through the sharing of clothing, particularly intimate apparel, towels, sheets, and pillow cases.
To diagnose scabies, a physician may scrape possible burrows and examine their contents under the microscope. Discovering adult mites or their eggs confirms a suspected case. Sometimes a physician will coat suspected burrows with a liquid tetracycline derivative and then examine the area with a special fluorescent light, known as a Wood's light, looking for the characteristic fluorescent yellow streak of a true burrow. A doctor rarely needs to biopsy a suspected site that is, inject a small amount of local anesthetic to numb the area and then surgically remove a small piece of skin tissue to be examined under the microscope.
Fortunately, scabies can be cured quite easily these days. A relatively new topical medication, Elimite, a permethrin-containing compound, has proved safe and effective in eradicating most cases of the infestation and is today the treatment of choice. Lindane lotion (Kwell) and crotamiton lotion (Eurax) are effective alternatives. Regardless of the agent chosen, in order to be optimally effective it must be left on overnight. In addition to the medication, all bedclothes, sheets, towels, and linens must be dry-cleaned or laundered in hot water the morning after application in order to ensure destruction of all mites and to prevent reinfestation. Because of the high likelihood of spreading the infestation, other close family members should be examined and treated simultaneously to prevent a cycle known as "Ping-Pong" reinfestations. Finally, since itching often persists for days or even weeks after adequate treatment and destruction of the mites, you may have to continue oral antihistamines, topical anti-itch medications, and topical steroid creams during this period.
