CHICKEN-POX.—SYNON.: Varicella; Fr. La Varicelle; Ger. Wasserpocken.
Dictionary of Medicine , Longmans, Green & Co, London 1894

DEFINITION.—An acute specific infectious disease, characterised by the appearance, in successive crops, of red spots, which in the course of about a week pass through the stages of pimple, vesicle, and scab.

AETIOLOGY.—The origin of this disorder is-unknown. It is certain that it arises from contagion, and that childhood is its predisposing cause. It occurs in children at the breast, and is seen with increased frequency up to the fourth year, at which period it attains its maximum. It is less often found between four and twelve, and after twelve it may be said to disappear, although it is occasionally seen in adults.

SYMPTOMS.—The illness commences with out any, or with but slightly-marked, premonitory symptoms. There is usually some feeling of lassitude, and the patient goes to bed earlier than usual. Within a few hours a" eruption appears, generally on some part of the back or chest, but there are many exceptions to this rule. It may commence on the face, neck, chest, abdomen, or extremities, or upon several of these parts at the same time. The eruption consists of small, faintly papular rose-spots, varying in number from twenty to one or two hundred. These, in the course of eight, twelve, or, at the most, twenty-four hours from their appearance, change into vesicles, which, at first small in size and clear as to their contents, become quickly large; globular, or semi-ovoid, in form; translucent, glistening, and opalescent in appearance; and surrounded with a faint areola. Towards the end of the second day of illness, the vesicles attain complete development, and about this time a few may be seen on the sides of the tongue, on the lips, cheek, or palate, and sometimes upon the mucous membrane of the genitals. About the third day a few of the vesicles may have a pustular appearance, and sometimes a few pustules are seen; but, regarding the eruption as a whole, pustulation forms an incident rather than an essential feature in its progress. On the fourth day the vesicles begin to dry up, and by the sixth complete scabs are formed. These fall off in a few days, leaving in their place faintly red spots, and sometimes a few pits. A single crop of eruption may be said to complete itself in five or six days; and, as two or three crops appear on as many successive days, the illness will last rather more than a week. In the event, however, of there being four or five crops, it may be prolonged for another week, but this is unusual. With the appearance of the eruption, the temperature rises two, three, or even more degrees, and this rise recurs with each successive crop of spots. The pulse is sometimes slightly increased in frequency; the tongue is moist, and sometimes covered with a light fur. As a rule, however, there is but little constitutional disturbance, although it is occasionally severe.

PATH0L0GY.—Chicken-pox is due to the reception of a specific poison, which after an incubation of about thirteen days, shows itself by an eruption upon the skin. What this poison is, how it enters the body, and what, if any, changes it produces upon the internal organs, the present state of our knowledge does not enable us to say. It affects the same individual once only, and it is perfectly distinct from modified small-pox, as the following considerations will show :—

1. Chicken-pox is characterised by the rapidity with which it runs through its stages; modified small-pox, on the contrary, is characterised by an interruption in the course of the disease at one or other of three points—the papular, the vesicular, or the pustular.

2. The chicken-pox eruption attains complete development by the end of the third day; in modified small-pox, should the eruption attain complete development, this will not occur before the ninth day, however much the disease may be modified.

3. In modified small-pox the premonitory symptoms are usually well-marked, often quite as severe as in the natural disease, and these last forty-eight hours, after which there is an eruption of small hard papules on the forehead, face, and wrists, followed by a fall of temperature. In chicken-pox the premonitories are most often wanting, and when present are slightly marked, and the eruption is followed by a rise in the temperature. It appears, moreover, upon any part of the body indiscriminately, and less frequently on the face than on other parts; and within a few hours—at the most within twenty-four—it has become vesicular; whereas in modified small-pox the vesicular stage is only reached forty-eight hours after the appearance of eruption.

4. The vesicles of chicken-pox are globular or ovoid in form, without any central depression; glistening or translucent in appearance and unicellular in structure. They collapse on pricking; and attain their maximum development in from twelve to eighteen hours. Modified and natural small - pox vesicles are flat and circular in form, always depressed in the centre, and sometimes umbilicated, of an opaque dirty white colour, and multicellular in structure. They do not collapse on pricking, and attain their maximum development at the end of the third day from their origin.

5. Small-pox is an inoculable affection; chicken-pox, according to reliable authority, is not.

6. When cases arise which all recognise to be modified smallpox, they are always accompanied by others which are more severe; and in epidemics these latter gradually become more numerous up to a point of maximum intensity, when they decline and the modified forms reappear. In chicken-pox there is no such gradual increase in the intensity of illness, and neither serious nor fatal cases form part of its epidemics, which prevail independently of small-pox.

7. Small-pox and vaccinia are often early followed, in the same individual, say within two or three years, by chicken-pox, and vice versa.

8. Chicken-pox, vaccinia, and small-pox have been known to follow in immediate succession in the same individual.

COURSE AND TERMINATION. — Varicella always runs a favourable course. It has no sequelae.

DIAGNOSIS.—It should be borne in mind that a sure diagnosis cannot be made in less than forty-eight hours. The appearance, however, of a crop of vesicles, followed on the next day by a second crop, points almost certainly to chicken-pox. Attention to this, and to the points noted under the head of Pathology, ought to make the diagnosis easy.

PROGNOSIS.—This is always favourable.

TREATMENT.—The patient should be confined to his room, perhaps in the more marked cases to his bed. His food should be that which is easy of digestion; and although no physician has recorded a fatal case, a child whose temperature rose to three, four, or six degrees above normal should be examined with care.



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