Scabies (Synonym: The Itch.)

Scabies (Synonym: The Itch.)

What is scabies?

Scabies, or itch, is a contagious animal-parasitic disease characterized by a multiform eruption of a somewhat peculiar distribution, attended by intense itching.

Describe the symptoms of scabies.

The penetration and presence of the parasites within the cutaneous structures besides often giving rise to several or more complete or imperfectly formed burrows, excite varying degrees of irritation, and in consequence the formation of vesicles, papules and pustules, accompanied with more or less intense itching. Secondarily, crusting, and at times a mild or severe grade of dermatitis, may be brought about. The parasite seeks preferably tender and protected situations, as between the fingers, on the wrists, especially the flexor surface, in the folds of the axilla, on the abdomen, about the anal fissure, about the genitalia, and in females also about the nipples, and hence the eruption is most abundant about these regions. The inside of the thighs and the feet are also attacked, as, indeed, may be almost every portion of the body. The scalp and face are not involved; exceptionally, however, these parts are invaded in infants and young children.

Is the grade of cutaneous irritation the same in all cases of scabies?

No; in those of great cutaneous irritability, especially in children, the skin being more tender, the type of the eruption is usually much more inflammatory. In those predisposed a true eczema may arise, and then, in addition to the characteristic lesions of scabies, eczematous symptoms are superadded; in long-persistent cases, indeed, the burrows and other consequent lesions may be more or less completely masked by the eczematous inflammation, and the true nature of the disease be greatly obscured.

What do you mean by burrows?

Burrows, or cuniculi, are tortuous, straight or zigzag, dotted, slightly elevated, dark-gray or blackish thread-like linear formations, varying in length from an eighth to a half an inch.

How is a burrow formed?

By the impregnated female parasite, which penetrates the epidermis obliquely to the rete, depositing as it goes along ten or fifteen ova, forming a minute passage or burrow.

Upon what parts are burrows most commonly to be found?

In the interdigital spaces, on the flexor surface of the wrists, about the mammæ in the female, and on the shaft of the penis in the male.

Are burrows usually present in numbers?

No. Several may be found in a single case, but they are rarely numerous, as the irritation caused by the penetration of the parasites leads either to violent scratching and their destruction, or gives rise to the formation of vesicles and pustules, and consequently their formation is prevented.

What course does scabies pursue?

Chronic and progressive, showing no tendency to spontaneous disappearance.

To what is scabies due?

To the invasion of the cutaneous structures by an animal parasite, the sarcoptes scabiei (acarus scabiei). The male mite is never found in the skin and apparently takes no direct part in the production of the symptom

The disease is contagious to a marked degree, and is most commonly contracted by sleeping with those affected, or by occupying a bed in which an affected person has slept. It occurs, for obvious reasons, usually among the poor, although it is now quite frequently met with among the better classes.

State the diagnostic features of scabies.

The burrows, the peculiar distribution and the multiformity of the eruption, the progressive development, and usually a history of contagion.

How do vesicular and pustular eczema differ from scabies?

Eczema is usually limited in extent, or irregularly distributed, is distinctly patchy, with often the formation of large diffused areas; it is variable in its clinical behavior, better and worse from time to time, and differs, moreover, in the absence of burrows and of a history of contagion.

How does pediculosis corporis differ from scabies?

In the distribution of the eruption. The pediculi live in the clothing and go to the skin solely for nourishment, and hence the eruption in that condition is upon covered parts, especially those parts with which the clothing lies closely in contact, as around the neck, across the upper part of the back, about the waist and down the outside of the thighs; the hands are free.

State the prognosis of scabies.

It is favorable. The disease is readily cured, and, as soon as the parasites and their ova are destroyed, the itching and the secondary symptoms, as a rule, rapidly disappear.

How is scabies treated?

Treatment is entirely external, and consists of a preliminary soap-and-hot-water bath, an application, twice daily for three days, of a remedy destructive to the parasites and ova, and finally another bath.

Inquiry as to others of the family should be made, and, if affected, treated at the same time. The wearing apparel should be looked after—boiled, baked, or sulphur-fumigated.

What remedial applications are employed in scabies?

Sulphur, balsam of Peru, styrax, and β-naphthol, singly or severally combined. In children, or in those of sensitive skin, the following:—

  ℞ Sulphur. præcip., ................................ ʒiv
Balsam. Peruv., .................................. ʒij
Adipis,
Petrolati, .....................āā................ ℥iss. M.

And in adults, or those of non-irritable skin:—

  ℞ Sulphur, præcip., ................................ ℥j
Balsam. Peruv., .................................. ℥ss
β-Naphthol, ...................................... ʒij
Adipis,
Petrolati, ..............āā......... q.s. ad. .... ℥iv. M.

Styrax is a remedy of value and is commonly employed as an ointment in the strength of one part to two or three parts of lard.

Is one such course of treatment sufficient to bring about a cure?

Yes, in ordinary cases, if the applications have been carefully and thoroughly made; exceptionally, however, some parasites and ova escape destruction, and consequently itching will again begin to show itself at the end of a week or ten days, and a repetition of the treatment become necessary.

Does the secondary dermatitis which is always present in severe cases require treatment?

Only when it is unusually persistent or severe; in such cases the various soothing applications, lotions or ointments employed in acute eczema are to be prescribed.

Is a dermatitis due to too active and prolonged treatment ever mistaken for persistence of the scabies?

Yes.