Measles in Glasgow in 1808 and 1811-12: Researches of Watt.
The measles epidemic of 1808, which appears to have been somewhat general in England and Scotland, made an extraordinary impression in Glasgow. That disease had never before been nearly so mortal there, nor had any infection since the time of the plague, not even smallpox itself, engrossed the burial registers so much as measles did in the months of May and June, 1808. Glasgow had been the worst city in the kingdom for smallpox; by a somewhat sudden transition the infancy of the city died for a few months in larger numbers by the new disease than by the old. The highest monthly mortalities from smallpox had been 114 in October and 113 in November, 1791, the population being 66,578; but in 1808, the population having increased to 100,749 by the census of 1811, measles carried off 259 children in May and 260 in June, and in the months before and after as follows:
Measles in Glasgow, 1808.
| Month | Deaths | |
| Jan. | 2 | |
| Feb. | 2 | |
| March | 5 | |
| April | 71 | |
| May | 259 | |
| June | 260 | |
| July | 118 | |
| Aug. | 32 | |
| Sept. | 22 | |
| Oct. | 10 | |
| Nov. | 4 | |
| Dec. | 2 |
The figures were not known at the time; but every doctor in Glasgow, as well as the whole populace, knew that measles was cutting off the infants, while smallpox had fallen to insignificance. So dramatic was this turn in the public health that the common people set it down to the new practice of inoculating children with cowpox: ready to believe anything of vaccination, they concluded that, if it kept off smallpox, it brought on measles. Dr Robert Watt took the trouble to refute this singular notion; he found in his own practice that three children in one family, and in another two, had died of measles who had neither been vaccinated nor had smallpox before. Another great epidemic of measles arose in Glasgow three years after, in the winter of 1811-12:
| Measles deaths | |||
| 1811 | October | 12 | |
| November | 76 | ||
| December | 161 | ||
| 1812 | January | 130 | |
| February | 61 | ||
| March | 30 | ||
| April | 19 | ||
| May | 15 | ||
| June | 18 |
Those two great epidemics of measles in Glasgow, in 1808 and 1811-12, were the occasion of one of the earliest and most memorable inquiries in vital statistics in this country, the research by Dr Robert Watt on “the Relative Mortality of the Principal Diseases of Children, and the numbers who have died under ten years of age in Glasgow during the last thirty years[1218].” Having begun with a search of the principal Glasgow burial-registers for deaths by whooping-cough, he extended it to sixteen folio volumes of the registers of all the burial-grounds, old and new, and included the mortalities from all causes with the ages at death, and from fevers and the principal diseases of infancy and childhood. The increase of population from 1783, when his figures begin, to 1812, the date of his writing, was known to him; but as the numbers living at the respective periods of life were not known, he was obliged to state the change in the mortalities at the various ages, and from the various diseases, in ratios of the annual deaths from all causes,—a perfectly scientific comparison so long as the nature of the ratios compared was clearly stated. It would have been more satisfactory, of course, if the comparison could have been made in terms of the annual death-rate, which was much lower (for reasons already explained), in the second half of his period than in the first; but, in the circumstances, that was impracticable, and Watt did the next best thing. The following is the principal part of his table of ratios in five successive periods of six years each:
Vital Statistics of Glasgow in sexennial periods, 1783-1812. (Watt.)
| Period | Sum of all deaths | Per cent. under Two | Per cent. from Two to Five | Per cent. from Five to Ten | Per cent. of Smallpox | Per cent. of Measles | Per cent. of Whooping-cough | Per cent. of “Bowel-hive” | ||||||||
| 1783-88 | 9994 | 39·40 | 10·66 | 3·42 | 19·55 | 0·93 | 4·51 | 6·72 | ||||||||
| 1789-94 | 11103 | 42·38 | 11·90 | 3·79 | 18·22 | 1·17 | 5·13 | 6·43 | ||||||||
| 1795-1800 | 9991 | 38·82 | 12·21 | 3·45 | 18·70 | 2·10 | 5·36 | 6·47 | ||||||||
| 1801-06 | 10304 | 33·50 | 13·43 | 5·10 | 8·90 | 3·92 | 6·12 | 7·27 | ||||||||
| 1807-12 | 13354 | 35·89 | 14·22 | 5·58 | 3·90 | 10·76 | 5·57 | 9·26 |
The actual deaths from smallpox, measles and whooping-cough are shown in the next table, which includes for comparison the corresponding figures from the London bills of mortality:
Smallpox, Measles and Whooping-cough in London and Glasgow, 1783-1812.
| London | Glasgow | |||||||||||
| Year | Smallpox | Measles | Whooping-cough | Smallpox | Measles | Whooping-cough | ||||||
| 1783 | 1550 | 185 | 268 | 155 | 66 | 153 | ||||||
| 1784 | 1759 | 29 | 457 | 425 | 1 | 41 | ||||||
| 1785 | 1999 | 20 | 194 | 218 | 0 | 34 | ||||||
| 1786 | 1210 | 793 | 200 | 348 | 2 | 173 | ||||||
| 1787 | 2418 | 84 | 228 | 410 | 23 | 57 | ||||||
| 1788 | 1101 | 55 | 298 | 399 | 1 | 17 | ||||||
| 1789 | 2077 | 534 | 374 | 366 | 23 | 45 | ||||||
| 1790 | 1617 | 119 | 391 | 336 | 33 | 177 | ||||||
| 1791 | 1747 | 156 | 279 | 607 | 4 | 117 | ||||||
| 1792 | 1568 | 450 | 311 | 202 | 58 | 68 | ||||||
| 1793 | 2382 | 248 | 352 | 389 | 5 | 112 | ||||||
| 1794 | 1913 | 172 | 469 | 235 | 7 | 51 | ||||||
| 1795 | 1040 | 328 | 311 | 402 | 46 | 180 | ||||||
| 1796 | 3548 | 307 | 536 | 177 | 92 | 60 | ||||||
| 1797 | 522 | 222 | 567 | 354 | 5 | 76 | ||||||
| 1798 | 2237 | 196 | 418 | 309 | 3 | 98 | ||||||
| 1799 | 1111 | 223 | 451 | 370 | 43 | 95 | ||||||
| 1800 | 2409 | 395 | 380 | 257 | 21 | 27 | ||||||
| 1801 | 1461 | 136 | 428 | 245 | 8 | 125 | ||||||
| 1802 | 1579 | 559 | 1004 | 156 | 168 | 90 | ||||||
| 1803 | 1202 | 438 | 586 | 194 | 45 | 60 | ||||||
| 1804 | 622 | 619 | 697 | 213 | 27 | 52 | ||||||
| 1805 | 1685 | 523 | 703 | 56 | 90 | 129 | ||||||
| 1806 | 1158 | 530 | 623 | 28 | 56 | 162 | ||||||
| 1807 | 1297 | 452 | 439 | 97 | 16 | 85 | ||||||
| 1808 | 1169 | 1386 | 326 | 51 | 787 | 92 | ||||||
| 1809 | 1163 | 106 | 591 | 159 | 44 | 259 | ||||||
| 1810 | 1198 | 1031 | 449 | 28 | 19 | 147 | ||||||
| 1811 | 751 | 235 | 486 | 109 | 267 | 62 | ||||||
| 1812 | 1287 | 427 | 508 | 78 | 304 | 103 | ||||||
The ratio of deaths under the age of two had decreased greatly in Glasgow, while the ratios from two to five and from five to ten had increased. At the same time smallpox had almost ceased (but only temporarily, as it appeared) to be the great infectious scourge of infancy, while measles had come in its place. “Now that the smallpox are in great measure expelled,” (Watt believed that cowpox inoculation had done this), “the measles are gradually coming to occupy the same ground which they formerly occupied. I am sorry to make this statement, but the facts, at least with regard to Glasgow, are too strong to admit of doubt.”
In order to explain the enormous increase of deaths by measles, he had recourse to the following argument. Formerly nearly all children, say nine-tenths, had both smallpox and measles, the attack of smallpox in most cases coming first. Children who had survived smallpox were fortified by that ordeal, not merely as selected lives, but positively fortified, so that measles, when it assailed them in due time afterwards, was taken mildly or was “modified,” not one in a hundred cases proving fatal. But now (1813), when so few children have been through the smallpox, measles has become ten times more fatal to them, although it could hardly be more common than it used to be. Having found it necessary to assume that children in former times took smallpox before they took measles, nine-tenths of them taking both, he qualifies this in another passage: “Still, however, as the measles came round now and then, as a very general epidemic, they must occasionally have had the precedence, and it was perhaps chiefly among such patients that the disease proved fatal.”
The measles which came round now and then as a general epidemic was nearly the whole of it; even in London there were intervals of several years with only a few annual deaths, and in smaller towns or country districts the clear intervals were longer. The prevalence of measles on the great scale being more casual than that of smallpox, it is likely that most children had taken smallpox before they incurred measles. But it is clear from such instances as the London epidemic of 1674, and the epidemic in the Foundling Hospital in 1763, that measles might attack children just before smallpox, and by its weakening effects, increase the number of victims of the latter. As to the fatality of measles itself in the 17th and 18th centuries, the statement of Watt that it did not amount to one death in a hundred attacks, while it can neither be proved nor disproved by an array of figures, can be shown to be inconsistent with the language of annalists. The epidemics of measles varied in severity then as afterwards: that of 1670 in London was regular and mild, that of 1674 in the very same months of the year was anomalous and fatal; Huxham characterizes the measles at Plymouth in the winter of 1749-50 as “maximé epidemici, imo et saepe pestiferi”; at Kidderminster, in 1756, after fevers had been very fatal to adults, the measles went through the town so that an immense number of children “died tabid”; in the West of England about 1760 a disease called measles made “a melancholy carnage amongst children.”
While Watt’s theory of the working of this principle of substitution is open to criticism on some points of detail, the law itself, as enunciated by him, remains to the present time one of the soundest and most instructive generalities in epidemiology. He based it upon a laborious search of the burial registers, such as no one before him in this country had undertaken. Next he saw correctly that a great rise in the deaths of infants by such a disease as measles could only be accounted for by a great increase in the rate of fatality. Thirdly, he connected the loss from measles with the saving from smallpox. Adopting an old opinion, which may be discovered in Willis[1219], he argued that smallpox, when taken first, served to fortify children so that they passed easily through the measles afterwards; but in the following passage he indicated a better reason why the absence of smallpox gave measles the chance of proving more fatal: “In this point of view we are not to consider the smallpox as so peculiarly fatal in their nature. They perhaps prove so fatal merely by having the start of other diseases. The measles, the chincough, the croup, the scarlet fever, and perhaps many others, would have proved equally fatal had they occurred first.” The principle is true to this extent, that a certain proportion of weakly infants, or children of poor stamina, will succumb to almost any disease—if not to smallpox, then to measles, and if not to measles directly, then to the sequelae of measles. This was perceived in the form of a necessary truth by Haygarth in 1793: “A considerable number of those who now die of the smallpox would die in childhood of other diseases if this distemper were exterminated[1220].” It was commonly believed that smallpox had at length found its real artificial check, not in the inoculation of itself, but in the inoculation of cowpox. At all events it had declined greatly in Glasgow. During the three years before the measles epidemic of 1808, there could hardly have been more than a thousand children attacked by smallpox, or not one in ten of all the children born. During several years the infancy of the city had been spared any great ordeal of infectious disease; the first epidemic that came along happened to be measles, so that it fell to that infection to take off the weaklings. In the economy of nature it is impossible to rear all the young of a species, nor would it be good for the species if it were possible. It is among the birds that the principle of population, or of the survival of the fittest, is seen working in the most admirable way: the annual migration of many species to breed in a remote country brings with it an ordeal for the birds of the year in finding their way to the winter feeding-grounds—an ordeal which only the strongest come through. For some unexplained reason, the young of the human species are peculiarly tried by infectious diseases, which multitudes pass through safely, while many of poor stamina or of ill tending are cut off.
Dr Watt’s teaching, as to the displacement of one infectious cause of death by another was resisted at the time as being of “evil tendency” for the pretensions of vaccination, although Watt believed as firmly in the virtues of cowpox as Jenner himself did. Writing to James Moore on 6 Dec. 1813, Jenner says of Watt’s essay (Baron, II. 392): “There is nothing in its title that developes its purport or evil tendency.... Is not this very shocking? Here is a new and unexpected twig shot forth for the sinking anti-vaccinist to cling to.” Sir Gilbert Blane, who was then president of the Medical and Chirurgical Society, having a natural fondness for ideas of all kinds expressed in a paper to that society rather more approval of Watt’s view than was thought prudent: “An ingenious friend of mine has remarked to me in conversation that some light is thrown on this subject by considering that whichever of the epidemic maladies attack children first, it will be the most fatal, inasmuch as all feeble constitutions will fall in its way while the stronger will be left to encounter the attacks of the others; and that the smallpox, owing probably to the greater abundance and rankness of their effluvia, are generally caught in a casual way before measles, hooping cough and scarlet fever, and are therefore reckoned more fatal than any of these. But, a new field of research being opened,” etc. Efforts were made to correct the effect of this, by showing that measles in some parts of the country had not been more fatal than usual. Holland, of Knutsford, attributed the fatality of the epidemic in 1808 to a change of the wind to the east. Writers in the Edinburgh Med. and Surg. Journal, pointed out that Watt had compared the absolute deaths by smallpox at one time and by measles at another without taking account of the increase of population, and the rates of mortality from each disease. The best criticism of Watt was by Roberton in his Mortality of Children, 1827, p. 49. He offers the following considerations, without seeming to know that they were really to be found in Watt’s own essay: Smallpox used to be caught first; it swept off the feeble and sickly, leaving the strong and vigorous only to encounter the attacks of other diseases. “That infectious febrile disease to which in early infancy there is the strongest predisposition will of course in general make the first attack and prove the most fatal of any.” There were reasons why measles used to have comparatively few victims, “and why, when they now prevail epidemically, they, as was the case with smallpox, are caught at an earlier age than other diseases in general and prove so very fatal: which happens not more from their priority in attack than from being in their nature what they were ever considered—a severe and dangerous disease. We are to recollect, however, that measles do not in general attack at so early an age as smallpox; nor ever, like the latter, destroy eight or nine-tenths of all the children that die in the place where they happen to prevail, as was the case in the variolous epidemics of Chester and Warrington [this is an error, vide supra, p. 554]; consequently we have reason to hope that neither measles nor any other infantile disease will, as Dr Watt imagined, ‘come to occupy the place which smallpox once occupied,’” (p. 58). A feeble echo of Roberton’s criticism, with all its scientific candour left out and its points against Watt emphasized in a spirit of paltry cavilling, was heard next year in the Goulstonian Lectures of Bisset Hawkins on Elements of Medical Statistics, 1829.
Many years after, when the enormous increase of deaths by scarlatina was illustrating the doctrine of displacement in a new way, Dr Farr gave a full analysis of Watt’s essay in his annual Letter to the Registrar-General for the year 1867, and endorsed the Glasgow teaching of 1813 with more heartiness than it had hitherto received. Although Farr did not take the Malthusian view that the loss of weakly children by one means or another was inevitable, yet he could not help seeing, in his work upon the registration returns from 1837 onwards, that one infection had been taking what another spared. He recurred to Watt’s doctrine time after time in his annual reports, and in that of 1872 (p. 224), expressed his belief thus plainly: “The zymotic diseases replace each other; and when one is rooted out, it is apt to be replaced by others which ravage the human race indifferently whenever the conditions of healthy life are wanting. They have this property in common with weeds and other forms of life: as one species recedes, another advances.”
Two remarks remain to be made under the doctrine of displacement. The first is that the substitution of measles for smallpox was one of a series of such changes in the public health of Britain. The great infective scourge of medieval and early modern periods had been plague, which destroyed at times immense numbers of the valuable or mature lives. Its successor was typhus fever, which also cut off the parents more than the children, but did not retard population as the plague had done. The saving of life by the extinction of plague was in great part balanced by the loss from smallpox, which fell, however, more and more upon the earliest years of life until at length it was almost confined to them. The first great decline of smallpox itself corresponded to a great decline of typhus fever during the second half of the French war; but while there was no great infectious disease in those years to thin the ranks of the adults, measles took the place of the more loathsome smallpox in cutting off a certain number of young lives. While the older types of infection have disappeared, the incidence has shifted from mature lives to children, so much so that at the present time enteric fever, and occasional choleras and influenzas, are almost the only infections that correspond to the old plague and to typhus fever in their age-incidence.
The other remark is that the greater prevalence or fatality of measles, as if in lieu of smallpox, meant a good deal more for the bills of mortality than actually appeared under the name of measles. Smallpox was not an infection that did much constitutional damage to those that came through it, although it sometimes destroyed the vision and spoiled the beauty of the face. On the contrary, it was held by many that the general health was better after an attack of smallpox than before; and, if personal experience can justify an opinion, that ought to be my own view of the matter[1221]. But measles is an infection peculiarly apt to leave mischief behind. The bronchial catarrh, which is an integral part of the malady, and is often the cause of death in the second stage of the attack, may so affect weakly children that the respiratory organs are permanently damaged. Tuberculosis of the lungs is apt to follow measles. Some children, again, fall into mesenteric disease after measles, and die tabid, the intestinal catarrh being as dangerous in one way as the bronchial is in another. Another large proportion of the subjects of measles take whooping-cough[1222]. While smallpox did its work summarily, the full effects of measles were longer in being realized. This may in part explain the fact brought out by Watt, that while fewer children died under two years of age, measles being the dominant epidemic disease, there was an increase in the ratio of deaths from all causes between the years of two and five and from five to ten.