Gaulard then declares, “that though reason dictates, and experience actually demonstrates, that this process (inoculation for Small Pox) does not infallibly afford protection against a subsequent attack of natural Small Pox, he was still disposed to believe that it may be possessed of some real advantages” (p. 59). “Dr. Cantwell, in 1755, published a dissertation upon inoculation, the avowed object of which was to undeceive those who believed in the efficacy of that practice. In this Essay, a great number of cases of Small Pox, which had occurred both after natural and inoculated Small Pox, are mentioned” (p. 64). “He (Dr. Cantwell) seems to have been well acquainted with those varioloid eruptions which, previous to the introduction of inoculation, had received a variety of names, such as Swine Pox, Chicken Pox, &c. and which were considered not as specifically different from Small Pox, but as spurious and bastard species of that disease. These eruptions, in his opinion, were nothing else than mild varieties of the true Small Pox. His own words are” (p. 37), “after all, what are the Swine Pox, the Duck Pox, and the Chicken Pox, which are observed among the English and the Irish? What is the petite verole volante which is seen in France? Many distinguished authors attest, that they have seen Small Pox occur twice in the same individual; and have not we reason to believe that, in these cases, the second attack was true Small Pox, of which the infection was slight, and in which the vital actions were too weak to carry it to a certain extent?” All this appears to me most strictly consistent with truth. But Dr. Cantwell was arguing against the use of inoculation. How then did he account for the fact that “the infection was slight,” and that “the vital actions were too weak to carry it to a certain extent,” if it did not arise from these individuals having already passed through the disease of Small Pox?
“De Haen (a celebrated physician of Vienna,)” says Dr. Thomson (p. 68), “collected into a body the numerous cases of secondary Small Pox, which are to be found in the writings of physicians, who lived previous to, and in the infancy of, the practice of inoculation in Europe. Had the number of these cases, and the respectability of the individuals by whom they are related, been duly considered, they surely were more than sufficient to have satisfied the minds of the most incredulous, of the possibility, and even of the frequency of secondary Small Pox.” De Haen, however, was an opposer of inoculation, and the facts he adduced were not permitted to have the weight which they merited, in consequence of the arguments he deduced from them.
I shall conclude my extracts from the fund of evidence collected in the work of Professor Thomson, with the following:—
“M. Strack, professor of medicine at Mayence, in a letter upon inoculation, addressed to M. Roux in 1765, (Journ. de Med. tom. xxii.) maintains that natural Small Pox do not, any more than the artificial, protect against a second attack. In proof of his opinion, he mentions six cases of secondary Small Pox which he himself had attended. The argument which he uses in support of inoculation, in opposition to those who were hostile to that practice, and who asserted that it does not protect against a subsequent attack, though novel at the time it was employed, has since been sufficiently confirmed by repeated observation. He says, that those who have passed through the Small Pox twice, whether naturally or artificially, have, in general, escaped without danger; those patients, he adds, who have had the Small Pox at two different periods, are fortunate, because if the variolous miasma had operated with its full force during the first attack, they probably would have fallen victims to the disease” (p. 77).
Mr. Moore remarks (Hist. of Small Pox, p. 278) that, “besides the foreign authorities, the English Medical Journals contain several authentic examples of persons whose faces were strongly pitted with Small Pox, and who were afterwards destroyed by a second attack of that disease,”—he goes on (p. 279) to relate “an incident frequently repeated by the late Dr. Reynolds, Physician to his Majesty, who was sent for by a lady unknown to him, and conducted by her maid, rather mysteriously, into a handsome bed-chamber; where he saw, lying in a splendid bed, a lady masked. Being a good deal surprised, the maid stifled a laugh, while her mistress, in a soft toned voice, apologised for concealing herself even from a professional gentleman. This (she said) had become proper, from the peculiarity of her situation. At present she stood greatly in need of his superior medical talents, and was extremely anxious for his opinion on her case, which she understood from others, was a very rare one. The doctor being thus put upon his guard, enquired minutely into all the symptoms, and examined critically a pustular eruption which was spread over the lady’s person: he then pronounced the disease to be, without all doubt, the Small Pox. On which the patient unmasked, and displayed features seamed with the disorder.”
Dr. Thomson (in his Historical Sketch, p. 279) informs us, that out of eight hundred and thirteen cases of Small Pox, which had come under his notice since June, 1818, “seventy-one had previously passed through Small Pox.” And in the sequel many other instances will be referred to.
In a late number of the London Medical Repository, Dr. Carter, of Canterbury, gives the details of a case of secondary Small Pox occurring in a girl, which proved fatal. And a young lady (a family connection of my own), who had satisfactorily passed through the disease, from inoculation, when young, had a second attack of Small Pox, when on a visit at Liverpool, to which she very nearly fell a sacrifice. To this mass of evidence I shall add the case to which I have before alluded, as having come under my own notice. In this young woman the eruption was confined to the shoulders and face, and was not numerous, but it was preceded for several days by considerable feverishness and head-ache; and although it did not proceed beyond the fourth or fifth day, I consider the nature of the disorder as quite unequivocal; if what I conceive to be the only true test of this be admitted, namely, that it was produced by Small Pox infection, and was capable of communicating it to others. Fortunately this test was left incomplete in this instance, no other individuals having become infected in consequence; but the following facts which have since come to my knowledge, seem to warrant the inference, that this might have happened had any unprotected persons been allowed to have communication with the patient.
A lady, residing at Gateshead, who passed through inoculated Small Pox many years ago, became lately (during her confinement) affected a second time with this disease. And notwithstanding that it was of the same mild character as in the last case, and that the eruption turned on the eighth day, her infant caught the infection. The eruption in the child was of the confluent kind, and occasioned its death eight days after the appearance of the disease.
Having succeeded, I trust, in proving to the entire satisfaction of every candid enquirer the possibility, if not the frequency, of the occurrence of Small Pox a second time in the same individual, it would be both interesting and useful, were it possible to ascertain what proportion such cases bear to those who escape a second attack; but many insurmountable difficulties present themselves in making such a calculation. Dr. Thomson tells us (p. 67), that “according to Tissot, the proportion of cases of secondary Small Pox, is as 1 in 100; according to Heberden, as 1 in 5000; and, according to Condamine, as 1 in 10,000. How uncertain the data!”—It is, however, enough to know, that while the relative number is sufficiently great to prevent the rule, That no individual can be affected by Small Pox oftener than once,—from being considered absolute, it is yet too small reasonably to shake our confidence in the fact, that a very large proportion will escape a recurrence of that disease. One other fact of considerable importance has, I trust, been also established by the preceding enquiry—That when secondary Small Pox does take place, it is usually a very mild disease, unattended with danger.
The fourth argument in support of the employment of inoculation for Small Pox,—that it was rendered comparatively mild and devoid of danger, while it afforded equal security against any future attack of the disease with natural Small Pox itself, need not detain us long.—The latter part of the proposition has been generally admitted; and its truth or falsity will not affect the object of our present enquiry. Mr. Moore (History of Small Pox, p. 302) tells us, that “at the commencement of inoculation in England, the proportion of fatal cases appears to have been fully one in fifty. But after the last improvement in treatment had been established, probably not more than one in two hundred were lost.”—Mr. Moore continues—“of those who contract the casual Small Pox, and are treated with medical care, it has been admitted that generally about one in six are lost: but in countries where the medical arts are unknown, the Small Pox is so fatal a disease that few of those who are seized with it survive its malignity.” The immense difference between these proportions is amply sufficient to prove the great advantage derived from inoculation by those on whom it was practised.