Varicella is an acute disorder of infancy and childhood, in the course of which appears a cutaneous exanthem of vesicular type, accompanied at times by systemic symptoms of moderate severity, terminating in the course of from three days to a fortnight, after the formation of relatively few crusts upon the skin, with occasionally persistent cicatrices.
SYNONYMS.—Eng., Chicken-pox; Ger., Windblattern, Schafpocken; Fr., Varicelle; Lat., Variola notha, seu spuria; Ital., Morviglione.
HISTORY.—The literature of the disease which is now best recognized under the title of varicella has been, in the history of medicine, wellnigh inextricably confused with that of variola. In the latter part of the seventeenth and the early part of the eighteenth century the distinction between typical forms of the two disorders became apparent, and was described by Willan and Harvey in England, and other writers in Germany, France, Holland, and Belgium. Among those who have contributed to its literature may be named Hebra, Kaposi, Trousseau, Simon, Thomas, Güntz, Henoch, Kassowitz, and Boeck.
ETIOLOGY.—Varicella is essentially a disease of early life, occurring almost exclusively in infants and young children. It is a contagious disorder, and at times, especially in hospitals and asylums for children, occurs in apparently epidemic forms. The question relating to the inoculability of the contents of its vesicular lesions is still open, positive and negative results being recorded by different experiments.1
1 The writer has purposely avoided, in the brief space here devoted to the disease under consideration, entering into a discussion of the question respecting the relation sustained by varicella to variola. On one side are the views entertained by the Vienna school of dermatologists, according to which there is but a single virus in these several forms of disease—the variolous poison. On the other are the opinions and the practice, largely based upon the latter, of most English and American physicians, who deny the existence of any relation between the pathological states recognized by them as occurring in two entirely distinct affections.
My personal view may be briefly formulated as follows: Practically and clinically, it is useful to regard these disorders as of a distinct nature. The arguments, however, in favor of such absolute distinction are not irrefutable. There is probably in both forms of disease but a single virus, that of variola; but this, modified by evolution among generations of vaccinated children, has, in this process of natural cultivation or attenuation, produced a malady of tender years whose attacks do not protect from variola and occur irrespective of vaccination.
SYMPTOMATOLOGY.—The period of incubation of the disease cannot be said to be definitely established. At times, without question, an entire fortnight elapses between the dates of exposure and the evolution of the disease, but both longer and shorter intervals have been recorded.
If there be a prodromal stage of the disease, certainly in the vast majority of the little patients it cannot be recognized. During the last month the writer has observed the evolution of the disease in twenty children gathered together in the Chicago Home for the Friendless, no one of whom was recognized as ailing before the eruption appeared. Occasionally the disease is preceded by mild or even severe febrile symptoms, accidents sufficiently common in this class of patients.
The exanthem, commonly the first symptom of the disorder, occurs in the form of reddish puncta, from which rapidly develop rosy-colored maculations, and these become tensely distended, transparent or slightly yellowish vesicles, of the average size of a split pea, though they are occasionally smaller or may enlarge to the dimensions of a bean or small nut. The eruption appears first upon the upper segment of the body, implicating the chest in front and behind, the neck, the scalp, particularly the extremities, and quite sparingly the face also, which may, however, entirely escape. In cases where the eruption is profuse it may be completely generalized, involving largely the trunk and extremities, the lesions, upon the back particularly, being as closely set together as in discrete variola. In many, even the majority, of cases the exanthem is much less profusely developed, not more than a dozen or twenty vesicles springing from the surface.