Small-pox.—At the present day, thanks to vaccination, and to re-vaccination, small-pox is rarely met with in the well-to-do classes of society, though it is not yet a century ago since it found its victims not only among the poor, but among the highest in the land. It does, however, occur sometimes after vaccination, and sometimes, though very rarely, an attack of small-pox fails to furnish an absolute guarantee against the occurrence of a second.
Small-pox, unmodified by previous vaccination, sets in in the child with violent sickness; vomiting, sometimes recurring frequently for forty-eight hours, with much depression, or even stupor; in some instances even actual convulsions, and fever; but neither with the sore-throat of scarlatina, nor with the sneezing, cough, and running at the nose of measles. At the end of from forty-eight to sixty hours, an eruption of pimples appears on the face, forehead, forearms and wrists, whence it extends to the body and the lower limbs. They are reddish in colour, rather pointed in form, and at first scarcely raised above the surface; so that the eruption looks at first like the very early eruption of measles; though the tiny pimples felt as if beneath the skin serve even then to distinguish the one disease from the other. In another forty-eight hours the character of the pimples has changed into that of little vesicles or pocks, depressed instead of pointed at their centre, and containing a little watery milky fluid. They next enlarge, and become once more prominent at their centre as they fill more and more with fluid, which becomes thicker, yellowish-white—looks like, and indeed is, matter. Four or five days are occupied with this process; the matter in the pocks then begins to dry, and scabs to form, which gradually by the end of another week drop off, and leave the skin spotted with red or even scarred if the pocks went deep enough to destroy the skin, and to leave the indelible marks, the so-called pitting of small-pox.
The danger of the disease is in childhood the nervous disorder at the outset, and then the exhaustion produced by the so-called maturation of the pocks when the thin watery fluid changes to the thicker matter, and depresses the patient in the same way as he would be depressed by an enormous abscess.
The first outbreak of the eruption is followed always by a most remarkable abatement in the disturbance of the constitution, and for three or four days, even though the eruption is abundant, the patient may seem so well that it is almost impossible to realise the imminent peril to which he will be exposed in a few days' time.
Inoculation and Vaccination.—The danger of small-pox is in direct proportion to the abundance of the eruption; and the great advantage of inoculation for the small-pox consisted in the much scantier eruption which followed it, as compared with that which commonly took place in the natural small-pox.
The same advantage in a greater degree is obtained by vaccination, even in the exceptional instances in which it fails to render the person altogether insusceptible to the disease.
The great advantage which inoculation secured was counterbalanced in great measure by the fact that it always maintained small-pox rife throughout the whole country, and that consequently all who either had neglected inoculation, or young children on whom, on account of their tender age, it had not yet been practised, were more than ever exposed to constant risk of infection.
This very real danger led to the almost unanimous welcome which the practice of vaccination received towards the end of the last century, since it was hoped that by it not only would the risk attending small-pox be lessened, and the disease when it did occur be even milder in character than inoculated small-pox, but that small-pox itself would eventually be extirpated.
These anticipations have not hitherto been fully realised; but the good effected by vaccination has been such as to render it, in the opinion of nearly everyone qualified to form an opinion on the subject, one of the greatest boons ever conferred on the human race.
Small-pox, like other eruptive fevers, has the peculiarity of occurring for the most part only once in a person's life. We do not know in the least on what this protecting influence depends. We know the fact, but are the less able to offer an explanation, since there are other constitutional diseases, such as gout and rheumatism, in which the local symptoms are equally the outcome of previous constitutional disorder, where exactly the opposite rule obtains, and in which their occurrence does but increase the liability to their return.