Definition.—An acute, specific, and infectious disease, occurring during infancy and early childhood, and characterized by an eruption that rapidly passes through the stage of papule, vesicle, and pustule, and terminates by desiccation, the entire period of this evolution not occupying more than from three to five days. There may be successive crops of the eruption.

The disease is attended by slight fever, though sometimes the thermometer will be the only means of revealing it. If ulceration takes place, the true skin is invaded and a pit or scar results.

Etiology.—All efforts to isolate the micro-organisms or the contagium, whatever that may be, have failed. While there is no doubt that the infectious material is to be found largely in the vesicle, it is also generally recognized as being in the expired air. It occurs sporadically or as an epidemic, and is essentially a disease of childhood, though adults are not entirely exempt.

It was at one time believed to bear some relation to small-pox, a modified form; but experiments have proven the erroneousness of this view, for chicken-pox never protects against small-pox, nor vice versa. One attack protects the individual from a second, the same as the eruptive fevers in general.

Pathology.—The only definite pathological condition arises from the exanthem. Dr. Hyde thus describes it: "Manifestly, the exanthem is exudative in type, the serum in circumscribed areas lifting the superficial layer of the epidermis from the deeper parts of the derm. Unquestionably, septa occur in typically developed varicella chambers, similar to those seen in variola, a pathological fact which is the corner-stone of the doctrine relating to the unity of the disorders. The serum contained in these septa possesses an alkaline reaction. The formation of a cicatrix is evidently due to the intensity of the process in certain exceptional lesions, as a result of which the papillae of the corium are superficially destroyed. These sequelae are often due to the picking .and scratching of the lesions."

Symptoms.—The period of incubation is usually longer in this than the other eruptive fevers, varying from ten to fifteen days, with an average of fourteen days. Prodromal symptoms are generally absent, though in exceptional cases there will be a chill followed by headache, restlessness, and fever. Convulsions are very rare. Usually the eruption is the first symptom to attract the mother's notice, and the one enabling the physician to make the diagnosis.

The eruption first appears upon the upper half of the body, upon the back, chest, and face, and especially over the scalp, then the body at large.

The eruption, at first somewhat resembling the rose rash of typhoid fever, appears as slightly elevated macules or papillae upon which the vesicles early make their appearance.

Within a few hours the vesicles become filled with a clear, colored fluid, the epidermal layer being very thin, giving the vesicle the appearance of a drop of water. The vesicles are round or oval, and vary in size from a pin-head to a small pea. Within twenty-four hours the contents become opaque, and soon turn yellow from the presence of pus cells, although they do not become purulent. They maturate rapidly, so that by the third day they are becoming brown, at which time they are flat or slightly depressed, with occasionally slight umbilication. There may be slight erythema at their base, or they may appear as set upon the surface, without any inflammation.

They vary as to number, from a scattered few to several hundred. In the case of my little niece, the vesicles through the hair were so numerous that one could scarcely place a finger upon the scalp without touching a vesicle, while the face and body were but little less affected, in fact resembled very much in appearance a case of confluent small-pox.

In well-marked cases, vesicles form upon the mucous surfaces, the inner surface of the lips, the roof of the mouth, and upon the soft palate.

The roof of the vesicle soon gives way, and they appear as small ulcers.

The stage of decline begins the third or fourth day, and as the contents become absorbed or ooze away, the vesicles become wrinkled or puckered, which are now brown in color, and begin to fall off by the fifth day; this continues for several days.

At first a purplish red spot marks the site of the vesicle, though the normal color is soon resumed. If the cutis vera has been invaded, a small circular white pit or scar follows, which is retained through life.

When the eruption is extensive, vesicles form upon the prepuce in the male and in the vagina in the female, which gives rise to painful and difficult urination.

Successive crops of vesicles appear, so that one can observe, on the same patient at one time, the eruption in all its stages, from the rudimentary macule to the desiccated pustule. The vesicles of the first crop are the most perfect, those following many times being aborted, the macule disappearing or the vesicle formed is small and imperfect.

There is usually but little systemic disturbance, though occasionally the little patient has quite an active fever and is quite sick for twenty-four or forty-eight hours. In rare cases the glands of the neck are swollen and painful.

Hutchinson describes a "varicella escharotica" in which gangrene occurs about the vesicles, and Andrew describes a hemorrhagic varicella in which there is bleeding from the mucous membrane.

Diagnosis.—As a rule the diagnosis is very easily made. The absence of prodromal symptoms, the appearance of the vesicles, which more clearly resembles a small, blister, the absence of the shotty papule and swollen base and red areola, and the early maturity of the vesicle, the successive crop of vesicles, whereby all stages of development are seen at one time, enable the physician to make a positive diagnosis.

Prognosis.—This is the most simple of the exanthematous fevers, and the prognosis is always favorable.

Treatment.—But little treatment is required. We direct a sponge-bath, and, if feverish, put the patient upon aconite and asclepias, or, if there is much itching or burning of the skin, use rhus tox.; especially is this indicated where the child is restless. Should the glands of the neck become swollen, phytolacca will be the better remedy, twenty drops to a half glass of water.

Should there be much itching, sponge with a weak solution of boracic acid, and see that the hands are bandaged or placed in mittens to prevent scratching; for if the vesicles of the face are torn, pitting will follow.

If the bowels are constipated, they should be moved with a mild cathartic.

The Eclectic Practice of Medicine, 1907, was written by Rolla L. Thomas, M. S., M. D.