Definition. A common, contagious, animal parasitic disease, due to the burrowing in the epidermis of the female acarus scabiei, characterized by itching and a multiform eruption.
Symptoms. The burrowing of the female acarus produces, in proportion to the sensitiveness of the individual skin, consecutive lesions of papules, vesicles, pustules, wheals, bullae and crusts which are aggravated by excoriations excited by unlimited itching. The latter is constant but invariably worse at night, when the warmth of the bed stimulates the activity of the parasite.
The pregnant female itch mite seeking a thin and fixed part of the skin, proceeds to force her head between the cells of the epidermis and completely buries herself within half an hour. She deposits an egg, then burrows farther on in an irregular, tortuous or rarely straight line. This burrow or cuniculus is from one-eighth to one-half an inch in length and shows on the surface in cleanly persons as white or delicately gray dotted lines but is more often brownish or black from the entanglement of dirt. The burrow contains the mother mite, which appears as a small white or gray dot and eggs, egg-shells, larvae, numphae and excrement. Long before the two months’ period in which the deposit of ova is completed, the earlier eggs have hatched out (in five or six days) and the new acari escape on to the surface, where the surviving female become impregnated and repeat the performance. The male acarus roams about the surface and has no share in the cutaneous business, except that of impregnation.
The particular seats of this irritation are the sides of the fingers and interdigital folds, flexor surfaces of the wrist and arm, axillary folds, umbilicus, inner sides of thighs and legs, breasts, penis, and the toes especially in infants. Neglect and long duration will tend to spread the disease until massive crusting and calloused formations develop 9scabies crustosa). Among the lepers in Norway such a condition has been called “Norwegian itch.”
Etiology and Pathology. Scabies is caused by the impregnated acarus or sarcoptes scabiei depositing her eggs between the cells f the epidermis, but uncleanliness, intimate and prolonged contact of one person with another, as between mothers and nursing infants, or two people sleeping in one bed, are predisposing factors. While it is seldom seen in the cleanly and is most common before the age of thirty, no age, station or sex is exempt. It is doubtful if the transference is occasioned by mere transient contact such as shaking hands, but being contagious to a marked degree, its contraction is possible in many and varied ways. Scabies is one of the most common diseases of the skin, occurring in from 2 to 8 per cent. of all cutaneous affections.
The habits of the parasite as already described comprise the essentials of the pathology of scabies because the skin manifestations are an artificial dermatitis therefrom. The mature female acarus is just discernible with the unaided eye as a white, roundish, shining body, and is half again as large as the male.
Diagnosis. The pathognomonic cuniculus may be mistaken for dark lines or dots of dirt upon the surface, but the latter may be wiped off with a cloth, white the former will not be affected. Other diagnostic worse at night, and often a history of contagion. The vesicles and pustules of eczema seldom remain discrete but tend to group and do not exhibit the same localization or separate excoriations as in scabies. Pediculosis corporis will show excoriations occurring on the shoulders, chest and around the waist, while the hands are free and the accompanying itching is often greater during the day. A few days’ antiparasitic treatment will cure or greatly improve scabies, while eczema, impetigo contagiosa, syphilis or other confusing diseases will not be affected and may even be aggravated.
Prognosis and Treatment. The former is always good, no matter how long the duration of the attack. Causal or antiparasitic local measures are always indicated and it is a mild form of insanity to employ internal medication except for secondary or accidental developments. Treatment aims to kill the parasite and relieve the dermatitis. As in any other disease the individual and the extent and course of the malady must be considered so that undue irritation will not ensue. The first step is to remove the outer layer of the epidermis and to thoroughly cleanse the surface by a hot water and soap bath if the disease be general, or if it is local, hot water and soap with pumice may be applied. Immediately after this scrubbing process, some antiparasitic proper to the condition of the skin, the age and circumstances of the patient should be applied. Sulphur ointment, 2 to 3 drams to the ounce of fresh lard, while a most convenient and effective application, should not be used impartially. It may be applied for two or three days, followed by a hot bath and a change to fresh clothing, underwear and bed linen. In place of the ointment, sulphur powder may be rubbed on the skin and placed between the sheets of the bed at night. There are a number of excellent combinations with and without sulphur which may be recommended:
R Sulphur. sublimat., 3iv-vj; 15-24
Bals. Peruv., 3iv; 15
Petrolati, aa q.a. 3iv 120 M.
R Betanaphthol, gr.1; 3 3
Adipis, 3jss; 45
Ol.rosae, mj; 06 M.
R Styracis liq., 3ss; 15
Adipis, q.s.ad 3ij; 60 M.
Styreax is well suited to cases of scabies occurring in women or children with delicate skins. Carbolic acid, balsam of Tolu, staphisagria, tar, oils of cinnamon, rosemary, mint and cloves and petroleum have been used, but present no advantages, unless a strong odor be considered beneficial, over the preparations mentioned. Few American patients need the heroic treatment used for quick cure of scabies in France and on the the Continent. Briefly, this consists of a thorough scrubbing with green soap and water for half an hour, followed by an hour;s not bath. After this an ointment composed of sulphur 2 parts, potass. carb. 1 part, and lard 12 parts, is thoroughly rubbed over the body. The patient resumes his clothing without removing the ointment, and one treatment usually suffices for a cure. Among the remedies used as adjuvants are ARs., Calcareasulph., Mercurius, Psorinum and Sulphur.