The epidemics of smallpox at Carlisle in 1779 and Leeds in 1781 were unusually mortal, for reasons analogous to those assigned in the case of Warrington. Both towns had increased fast in numbers, owing to the growth of the weaving and spinning industries, both were overcrowded, ill ventilated, and filthy, and both had high mortalities from typhus fever among the adults, as described in another chapter. At Carlisle, the great epidemic of smallpox, which was the children’s special scourge, came in 1779, two years before the typhus fever reached a height. The smallpox caused 90 deaths, while “a species of scarlet fever” at the same time caused 39 deaths. Heysham estimated somewhat vaguely that these 90 deaths occurred in 300 cases, or one case fatal in 3·3, which is double the average[1068]. Lucas gives the proportion at Leeds more exactly—462 cases, in six months, with 130 fatalities, or 1 in 3·5. The epidemic at Leeds in 1721-22, which Nettleton described as “more than usually mortal,” caused 189 deaths in 792 attacks, or 1 in 4·2. There were fewer attacks in the much larger population (17,117) of 1781, perhaps because there were fewer persons who had not had the disease already, and these almost exclusively the infants born and the young children who had grown up since the last epidemic[1069]. In those circumstances it is hardly surprising that the Leeds smallpox of 1781 should have been a degree more mortal than that of 1721-22, which was itself “more than usually mortal.”
A complete survey of smallpox in its great period, the eighteenth century, in all places and continuously from year to year, is impossible even if it were to be desired. Had it not been for the exact diligence of a few, especially in the North of England, we should have been left in doubt on some of the main epidemiological generalities. A system of registration such as was applied for the first time in the epidemic of 1837-39 would have saved much research and would have made it possible to bring the facts within a smaller compass. By comparison and classification of many scattered particulars we may still acquire a tolerably clear notion of what smallpox was in the 18th century. It was chiefly a disease of infancy and early childhood. It was always present in one part or another of the capital and of the larger towns, rising at intervals to the height of a great and general epidemic[1070]. At its worst, as in Glasgow, it took about a third part of the lives under the age of five, and perhaps a sixth part of the lives at all ages. It came in epidemics at somewhat regular intervals in the smaller towns, and at longer intervals in the country parishes. The village epidemics were apt to be very searching when they did come. Haygarth gives the instance of Christleton, a small village two miles from Chester, in 1778: “The distemper began in March and continued till October. At the commencement of the epidemic, 107 poor children had never been exposed to the variolous infection; of these 100 had the distemper, probably all who were capable of receiving the smallpox.” In all places, with the possible exception of London where the risks from infantile diarrhoea and “convulsions” were peculiar, it cut off the infants and young children more than any other single disease, infectious or other; and indeed it had few rivals among infectious diseases until towards the close of the century, being for a time the grand epidemic scourge of the first years of life just as the plague was once the unique scourge of youth and mature age. It was more mortal in some seasons than in others, and at certain places. Towards the end of the 18th century, much more is heard of it in the northern industrial towns than in England south of the Trent. If the statistics of Boston, Lincolnshire, are at all representative, smallpox certainly declined much in market towns in the last twenty years of the century. It appears to have declined also in the capital during the same period. In the parishes of Scotland, by the almost unanimous testimony of the articles which refer to it in the ‘Statistical Account,’ it had become much less frequent and less dangerous for some years previous to the publication of that work (1792-98). In Glasgow, with the worst statistics of children’s deaths in the whole kingdom, the maximum had been reached, and passed, in the period between the close of the American war and the first years of the great war with France. As the French war proceeded, and vast sums of public money were poured out (the bill being left to Prince Posterity to pay), the effects of this abundance were seen in the remarkable decline, and almost total disappearance, of fevers all over England, Scotland and Ireland. Corresponding with the lull in fevers there was a lull in smallpox, not so marked as the former, but very significantly covering the same period and lasting until the great depression of trade in 1816 which followed the Peace. This will appear in continuing the chronology of epidemics; but before we come to that, it remains to make clear the scientific or pathological nature of a new kind of inoculation which became at this juncture the rival of the old. The extent to which each of the rival methods was practised will become a subject of inquiry after the epidemic of 1817-19 has been dealt with.
Cowpox.
Much has been said, in previous sections of this chapter, as to the efforts of inoculators to reduce the effects of inoculated virus “to as low a degree as we could wish.” What kind of matter do you use? one inoculator would ask of another. The comparative trials of Watson had shown that serous or watery matter from an unripe pustule of smallpox, preferably from the unripe pustule of a previous inoculation on the arm, was most “successful,” the success being measured by the slightness of the effect produced at the time. The comparative trials of Mudge had confirmed that, but had gone a little farther in showing that these slight effects of crude or unripe matter left the constitution still open to the same effects by the same means, or to more severe effects by more severe means. What kind of matter to use was, accordingly, still an open question, which offered some scope for originality and ingenuity. Among other sources of crude or watery matter with bland properties was the glassy or watery variety of eruption called swinepox, which, like its congener chickenpox, was peculiar to man; and among those who tried that source of non-purulent matter for inoculation was Jenner, of Berkeley. It was in 1789 that he inoculated his child, aged eighteen months, with matter from the so-called swinepox of man. There was still another pox bearing the name of a brute animal, which was, however, a true affection of brutes—the cowpox or pap-pox. A farmer at Yetminster, Dorset, named Benjamin Jesty, had used matter from that source for the inoculation of his wife and two young children in 1774, with the result that the arm of the former was much inflamed and had to be treated by a surgeon. There seemed to be no good reason for preferring matter of such dangerous tendency, and the experiment was not repeated. A few years after, an apothecary of Lyme, in Dorset, is said to have heard of another case of the domestic use of cowpox matter for inoculation by the mistress of a farm house, and to have pressed this fact upon the attention of Sir George Baker; who, although a supporter of the mild or Suttonian inoculations with crude lymph, and by his own avowal a friend of experiments, did not favour the trial of matter from the pap-pox of cows, probably for the reason that he should have been departing from the ground-principle of inoculating for the smallpox if he were to go outside the class of variolous disease for his matter. The true virtuoso, however, has no antecedent objection to experimenting with anything. Sometime after Jenner had used the swinepox matter, he began to talk among his medical neighbours of using cowpox matter. But it was known that cowpox matter had properties and effects of its own, and that it would be a radical innovation to use it, a departure toto coelo from every modification hitherto tried in the inoculation procedure. Although it was also a pox by name, and although cowpox to the apprehension of a man of words or notions might seem to be in the same class as swinepox, glasspox, hornpox, waterpox or chickenpox, yet those who had ever seen it on the chapped hands of milkers would hardly admit that matter from such a source could serve for inoculation purposes unless upon wholly independent and original proof of efficacy. Jenner’s colleagues are reported to have denied that cowpoxed milkers escaped natural smallpox any more than their fellows[1071]. About the year 1794 Jenner began to press the subject upon the attention of his friends. His clerical neighbour, Worthington, mentioned it in one of his letters to Haygarth, of Chester, who replied, on 15 April, 1794:
“Your account of the cowpox is indeed very marvellous, being so strange a history, and so contradictory to all past observations on this subject, very clear and full evidence will be required to render it credible. You say that this whole rare phenomenon is soon to be published, but do not mention whether by yourself or some other medical friend. In either case I trust that no reliance will be placed upon vulgar stories. The author should admit nothing but what he has proved by his own personal observation, both in the brute and human species. It would be useless to specify the doubts that must be satisfied upon this subject before rational belief can be obtained. If a physician should adopt such a doctrine, and much more if he should publish it upon inadequate evidence, his character would materially suffer in the public opinion of his knowledge and discernment[1072].”
It is clear that Haygarth, who was well acquainted with epidemic smallpox and with inoculation, saw in this Gloucestershire idea something quite new as well as antecedently improbable. What the real novelty was will appear from the next historical reference to cowpox in an original work upon Morbid Poisons by Joseph Adams, a writer of the Hunterian school. All that Adams knew of the nature of cowpox previous to March, 1795, came from Cline, surgeon to St Thomas’s Hospital, who had been a fellow student of Jenner’s five and twenty years before, and kept up some correspondence with him. Adams is writing on the peculiar danger of ulceration and sloughing, or phagedaena, from transferring animal matters from one body to another, his last illustration having been the notorious phagedaenic ulceration of the gums, with rashes of the skin and constitutional effects so severe as to be fatal, which followed the transplantation of fresh teeth from one person to another in a number of cases about the year 1790 and led to the speedy abandonment of that unnatural practice[1073]. He proceeds to say, “Thus far we have only traced the poisonous effects of matter applied from one animal to another of the same class,” and then he brings in the illustration of cowpox to finish the chapter:
“The cowpox is a disease well known to the dairy-farmers in Gloucestershire. The only appearance on the animal is a phagedaenic ulcer on the teat, with apparent inflammation. When communicated to the human subject, it produces, besides ulceration on the hand, a considerable tumour of the arm, with symptomatic fever, both which gradually subside. What is still more extraordinary, as far as facts have been hitherto ascertained, the person who has been infected is rendered insensible to the variolous poison[1074].”
Jenner’s own essay on the cowpox, when it appeared at length in 1798, confirmed these statements as to the phagedaenic or corroding ulcerous character of the milkers’ sores, in his brief accounts of several cases, of which it will suffice to mention these two: William Stinchcomb, farm servant, had his left hand severely affected with several corroding ulcers, and a tumour of considerable size appeared in the axilla of that side; his right hand had only one small sore. A poor girl, unnamed, “produced an ulceration on her lip by frequently holding her finger to her mouth to cool the raging of a cowpox sore by blowing upon it[1075].” Inquiries made by Dr George Pearson in various other dairy counties of England brought out the same character of cowpox in milkers: the painful sores might be as large as a sixpenny piece, and might last a month or two, causing the milker to give up his work[1076].
As to the pap-pox itself, or cowpox in the cow, the most circumstantial account was obtained, a few months after Jenner’s first essay, by interrogating a veterinary surgeon or cow-doctor, one Clayton, who attended at most of the farms within ten miles of Gloucester: