BY JAMES NEVINS HYDE, M.D.
Variola is an acute, febrile, contagious, and systemic affection, preceded by an incubative period, characterized by the evolution of symptoms in a relatively determinate order, with a cutaneous efflorescence successively papular, vesicular, and pustular in type, followed by crusting, and terminating either fatally or by complete convalescence, with or without sequelæ in the form of multiple, circumscribed, and superficial cicatrices.
SYNONYMS.—Lat., Variola; Eng., Small-pox; Fr., Petite Vérole; Ger., Pocken; Ital., Vajuolo.
HISTORY.—Small-pox is a disease which, there is reason to believe, was first developed in the earliest ages of which the human family has record. Originating probably in China, India, and the adjacent countries of the Asiatic continent, its extension over Europe and America was, without question, in the line of progress pursued by the advancing centres of traffic and population. The earliest traces of its ravages can be dimly recognized in the descriptions of writers in the middle and latter parts of the sixth century. In the early years of the tenth century, however, a remarkably accurate picture of the disease was drawn by Rhazes, a physician of Bagdad. His treatise, translated by Greenhill for the London Pathological Society,1 sets forth the views of an Egyptian physician named Ahron, who wrote in the sixth century. After these dates the remarkable political and social changes in Europe, which are to be attributed either directly or remotely to the Crusades, contributed largely to the opportunities for the spread of the disease and to the occurrence later of those decimating epidemics which became veritable scourges. In the last century the resulting mortality in some of the countries of Europe was often equal to the entire population of one of their largest cities. If a modern traveller could find himself transported to the streets of the city of London as they appeared in the early part of the present century, it is probable that no peculiarities of architecture, dress, or behavior would be to him so strikingly conspicuous as the enormous number of pock-marked visages he would encounter among the people at every turn. In the face of all cavil and sophistry, medical science will always count among its greatest triumphs the modifications which variola has undergone since its preventive treatment was established upon a satisfactory basis by the discovery of the immortal Jenner.
1 A Treatise on the Small-pox and Measles, by Abu Becr Mohammed Ibn Zacaríyá Arrází, London, 1848.
The bibliography of the disease is extensive, and the list of authors contributing to the subject is enriched by the names of such men as Boerhaave, Van Swieten, Sauvages, Willan, E. Wagner, Johanny Rendu, Hebra, and, more lately, Kaposi.
ETIOLOGY.—Respecting the etiology of variola, it can scarcely be affirmed that our knowledge has been greatly extended since the date of the experiments of Jenner. There is no historical knowledge of its generation de novo; and the earliest cases of the malady must therefore be classed with the exceedingly rare instances of spontaneous cow-pox which have proved such a boon to the vaccini-culturists. To-day every case of small-pox is justly regarded as having been directly or indirectly transmitted from one or more individuals affected with a similar disorder. It is thus recognized as specifically infectious, contagious, and inoculable, its transmission occurring, first, without contact, by atmospheric conduction of a volatile contagious principle of unknown nature; second, with contact either by (a) actual transference of dry or moist infectious secretions deposited upon a susceptible surface, immediately or through the medium of garments, bed-clothing, paper money, and similar material substances; or (b) by inoculation of unprotected persons with the pathological product of an infected organism. There is no doubt but that the contagious principle displays its greatest activities in connection with the contents of the lesions undergoing a change from the vesicular to the pustular phases, though from the beginning to the end of the disease it is probable that all the tissues and fluids of the infected body are in various degrees capable of producing the malady in those who are unprotected. Furthermore, whether associated or not with an organic substance, the contagium of the disease is known to preserve the power of reproducing itself for a period lasting for weeks, months, and even a longer time. A field for its activities once secured, there is a period of time during which few if any evidences of its progress are declared, this period being abruptly terminated by distinct and characteristic symptoms. This is known as the period of incubation.
The nature of the contagium in small-pox has been the subject of much speculation, careful investigation, and experiment, the results having established but few facts of any practical value. There is at present no proof that any bacteria, vegetable germs, or other minute organisms foreign to the human body are the essential causes of the disease. It is certain that in health the human body is completely enveloped in a volatile medium emanating from the secretions of the glands of the skin, which can be recognized by some of the keen-scented lower animals when it is wafted through the air at a distance of several hundred feet from a single individual. It is reasonable to conclude that not only in small-pox, but in other contagious and infectious diseases, these emanations possess a pathological character, and become capable of transmitting such maladies from diseased to healthy organisms. Certain also it is that when the subjects of these diseases are crowded together, as in prisons, hospitals and camps, this contagious element gathers an unwonted intensity. By far the larger number of all transmissions of variola occur after inhalation of the infective medium—in other words, by the avenue of the lungs. It is probably for the same reason that the disease spreads more widely and with greater virulence during the cold seasons of the year, in this latitude especially from December to February—a time when the ventilation of inhabited dwelling-houses is usually much less perfect than in warmer weather.
The disease affects individuals of all ages and both sexes, not sparing the foetus in utero, and, in the case of the latter, occurring both with and without previous infection of the mother of the unborn child. Nowhere are its ravages so extensive and followed by such fatal results as among those who have long been unprotected by previous vaccination. Among the debilitated, as also among the very young and the very old, small-pox is liable to be followed by severe complications and a fatal result. Negroes, possibly in consequence of tendencies inherited through generations of unvaccinated ancestors, are particularly prone to the disease. Lastly, there is occasionally noted an individual idiosyncrasy, in consequence of which either a remarkable susceptibility to the disease exists or a no less singular immunity against its encroachment is conferred.