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scabies
(skaŽbēz)
a contagious skin disease caused by the itch mite, Sarcoptes scabiei, usually seen in folds of the skin, such as in the groin, under the breasts, or between the toes or fingers. It is often transmitted
as a sexually transmitted disease. Lesions are caused by the female mite, which burrows beneath the skin, digs a short tunnel, and lays eggs there. The eggs
hatch in a few days and the baby mites go to the skin surface, mate, and complete the life cycle. Symptoms are rare until
a month has passed, when the human host develops hypersensitivity to the mites, with itching that is often worse at night. By that point, the tunnels in the skin can be seen as slightly elevated
grayish white lines. The mite itself may be seen under a magnifying glass as a tiny black speck at the end of the tunnel.
Blisters and pustules also may develop in the skin near the tunnel.
Norwegian scabies
a rare, severe form of scabies associated with a heavy mite infestation, seen most often in persons who are demented or mentally
retarded, have lost sensitivity, have severe systemic disease, or are immunocompromised. This is apparently an abnormal host immune response to the mite. Characteristics include crusting dermatitis of the hands and feet; horny debris under the nails; red, scaling
plaques on the neck, scalp, and trunk; and usually lymphadenopathy with eosinophilia.
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