The symptoms to which the acarus scabiei gives rise are due to the irrita tion produced by the insect as it burrows in the skin. The female acarus works its way into the epidermis and forms a narrow tunnel called " cuni culus." The intense itching thus occasioned forces the child to relieve him self by scratching ; and the consequences are seen in the wheals, papules, vesicles, and even pustules which in a typical case are mixed up together in a manner which is very characteristic of the complaint.
The cuniculus or furrow appears as a whitish curved line, which when newly formed may be easily overlooked ; and in children, especially in in fants, who are well tended and frequently washed, may escape notice alto gether unless narrowly searched for. In hospital patients they are readily discovered as they become darker and more distinct from small specks of dirt. The furrow is about the eighth of an inch in length, but may be longer, and to the naked eye closely resembles the scratch of a pin. Viewed with a lens it has a dotted look, and sometimes at one extremity a small white object can be detected, which is the female insect. With care this may be extracted with the point of a pin.
In infants the furrows are rarely seen on the wrist and between the fin gers as they are in older children and in the adult. In these young sub jects they must be searched for on the abdomen, the waist, the buttocks, round the ankles, and on the soles of the feet ; but in babies in well-to-do families, where cleanliness is properly attended to, the sign may elude the closest inspection. In young children after the age of infancy they are also usually seated on the buttocks, feet, and ankles. It is only in children of five or six years and upwards that they are often to be detected between the fingers. The scalp and face are rarely attacked.
The itching to which the presence of this parasite gives rise is of the most distressing character, and at night may be extreme. The child will be seen to dig his nails into the skin in his efforts to obtain relief. As a consequence we find reddened linear scars from small furrows made by the nails; and as another result of the violent scratching, can usually dis cover small papules, often excoriated and tipped with a minute crust of dried blood, little vesicles, and even large deep-seated pustules. These lat ter are often seen on the soles of the feet. In very delicate subjects a real eczema may be set up either by the irritation of the nails or of the applica Lions used for the destruction of the parasite ; and large wheals of urticaria are far from uncommon.
Diagnosis. —The simultaneous appearance of a variety of eruptions on the body of an infant is a very suspicious feature ; and if with a lens we can succeed in discovering the characteristic furrow, no doubt can remain as to the nature of the complaint. In the case of an infant, the hands of the mother or nurse will be always found to be affected. Therefore in every
case of doubt a careful inspection should be made of the hands of the at tendant. In searching for the furrow in young children attention should be always especially directed to the buttocks, abdomen, and the soles of the feet. In older children the furrows may be seen between the fingers and on the wrist as in the „adult ; and as at this age, especially in boys, cleanliness of these parts is often neglected, the cuniculus seldom fails to be discovered.
Treatment.—Scabies can only be cured by local treatment which kills the parasitic insect, and the favourite and most efficacious remedy is the applica tion of sulphur ointment to the skin. It must be remembered that in chil dren, in infants especially, the skin is delicate and sensitive to irritants. Therefore, while care is taken to make effectual use of the salve so that the acarus may be destroyed, we should avoid maintaining the cutaneous irrita tion by too prolonged or too zealous application of the ointment. At night time the child should be first thoroughly washed over the whole body with a strong soap, and be then well bathed with warm water, so as completely to soften the skin and lay open such furrows as may be present by destroy ing their roofs. He should then be well dried, and an ointment made of half a drachm of precipitated sulphur to the ounce of lard must be rubbed into the skin of the whole body except, of course, the head. It is important that the salve be rubbed into the skin and not merely smeared over the surface. In the morning the skin should be again thoroughly washed. This one application will cure the disease in most children. It is advisable, however, to rub a little of the ointment into the parts which seem to have been especially affected for two or three nights longer. We should then pause to watch the effect of the treatment. Itching often continues for some time after the parasites have been destroyed, as a consequence of the various forms of eruption set up by the acarus. In cases where it is doubt ful whether the disease be cured or not, Dr. R. Liveing recommends an ointment made with the balsam of Peru ( 3 ij. to the ounce of lard).
If it be thought desirable to disguise the sulphur in the ordinary ointment, this can be done by a drop of creasote or oil of bergamot. Dr. Liveing prefers the precipitated to the sublimed sulphur, as being in a finer powder, and less irritating to the skin.
Instead of sulphur, an ointment may be used of liquid styrax (one part) and lard (two parts), or of powdered stavesacre and lard ( 3 ij. to the ounce) ; but these are distinctly inferior to the • sulphur. Ointments containing carbolic acid have also been made use of. It is advisable to well scald the underclothing of the patient, and after recovery to bake the outer garments, so as to insure the destruction of stray insects.