The considerable epidemic of 1755 is thus referred to by Fothergill in his monthly notes:

At that period there would have been an epidemic of measles in London every other year, or once in three years, with a fatality from the direct effects seldom more than a sixth part that of an epidemic of smallpox. A London writer some twenty years after said that few escaped measles in infancy or childhood, while the deaths put down to it were only a tenth part of those due to smallpox on an average of years[1199]. The proportion of measles deaths to smallpox deaths was nearly the same in Manchester for twenty years from 1754 to 1774, according to Percival’s table of the burials in the register of the Collegiate Church where most of the poorer class were buried[1200]:

Wherever we have the means of comparison by figures, it appears that measles caused by its direct fatality not more than a sixth part of the deaths by smallpox in Britain generally. But in the colonies, where an epidemic of smallpox was a rare event of the great seaports, and as much an affair of adults as of children, measles seems to have been more fatal, dividing with diphtheria or scarlatina the great bulk of the infectious mortality of childhood. Thus Webster enters under 1772: “In this year the measles appeared in all parts of America with unusual mortality. In Charleston died 800 or 900 children”; and under 1773: “In America the measles finished its course and was followed by disorders in the throat”—especially in 1775[1203]. It is only among the children of public institutions in England that we find in the corresponding period a similar predominance of measles and scarlatina over smallpox. In the Infirmary Books of the Foundling Hospital the more general outbreaks of smallpox cease after 1765, while epidemics of measles, extending to perhaps a third or more of the inmates, as well as great epidemics of scarlatina, begin after that date to be common[1204].

The general testimony in the last quarter of the 18th century is that measles, if a common affection, was not usually a severe one. Heysham, of Carlisle, says that measles came thither in 1786 from the south-west of Northumberland, “where, I am informed, they proved very fatal”; the epidemic began at Carlisle in August, and continued very general until January, 1787, but extremely mild and favourable, only 28 having died (26 under five years, 2 from five to ten), out of “some six or seven hundred, I suppose.” The previous epidemic of measles at Carlisle in 1780 (mortality not stated), had followed a most fatal epidemic of smallpox in 1779; and although the epidemic of mild measles in 1786 did not follow a great epidemic of smallpox, it followed a high and steady annual average of deaths of infants and young children from that cause year after year[1206]. In both years of the measles at Carlisle, there were no deaths from smallpox. In like manner at Leeds, in 1790, measles followed smallpox, and was extremely mild; Lucas wrote of it, “I have not seen one instance of a fatal termination[1207].” This was the time (1785) when Heberden said of the disease in London, just as Willis, Harris and others had said of it and of smallpox together a century before: “The measles being usually attended with very little danger, it is not often that a physician is employed in this distemper.”

Increasing mortality from Measles at the end of the 18th century.

There were epidemics of measles with high mortality in the 17th and 18th centuries, occurring in special circumstances of time and place, of which instances have been given. But in general the position of measles was not then so high among the causes of death in infancy and childhood as it afterwards became. It is not easy to demonstrate the exact proportions by figures, even for London; the bills of the Parish Clerks are less trustworthy for measles than for smallpox, for the reason that deaths from scarlatina were probably included among the former (see under Scarlatina). For example, the ratio of 1·10 per cent. measles deaths for the ten years 1781-90 in the following table should be only 0·70 if the 793 deaths in 1786, supposed scarlatinal, be left out. But, taking the bills as they stand, they show an increasing ratio of measles (as well as of whooping-cough) among the deaths from all causes towards the end of the 18th century.

Percentage of Measles and Whooping-cough in all London deaths, 1731-1830.

During the same period, the ratio of deaths from all causes under two years of age had decreased, while the ratio of deaths from two to five, and at all ages above five, had increased as in the following table, also compiled from the London bills beginning with the year 1728 when the ages at death were first published.

Ratios of Deaths from all causes under two years, from two to five, and above five, London, 1728-1830.

Thus, while measles (with whooping-cough) was usurping, so to speak, a larger share of all the deaths, the two first years of life were claiming a smaller share of the deaths from all causes as the probability of life was improving. The saving of infant life was due to various things, but especially due to the decline of smallpox, as described in another chapter. We may now turn to consider, by a less abstract method, the increase of measles mortality from the last years of the 18th century.

In Willan’s periodical reports of the prevailing diseases of London[1208], scarlatina declined in 1795 and became sporadic, after having been extremely fatal for a long period, while measles and smallpox began to extend about the end of that year, the former being for the most part mild in its symptoms and favourable in its termination, the latter often confluent, and fatal to children. The report for March and April, 1796, is that measles had become more severe, and had been followed by obstinate coughs; for May, that “smallpox and measles have prevailed more during this spring than has been known for many years past.” However, it was smallpox that occasioned the larger share of the deaths among infants and children. The next general view that Willan gives us of the relative importance of measles among the infectious diseases is under Oct.-Nov. 1799: “The measles, though extensively diffused, have continued mild and moderate. The scarlet fever has increased, since the last report, both in extent and in the violence of its symptoms; but the contagious malignant fever [typhus] has been the most frequent, as well as the most fatal, of all acute diseases.” There is little sign of fatal measles in the London bills during the years of distress, 1799-1801; but we hear of it in Scotland and Ireland, where there was probably less scarlatina. An Edinburgh observer of the prevailing diseases says that “several hundreds” died of measles there in the winter of 1799[1209]. In the Irish emigration to America, which took one of its periodic starts owing to the repressive measures following the rebellion of 1798 and the union with England, measles appears to have been the fatal form of infection among the children on board ship. A medical letter from Philadelphia, 10 December, 1801, says that measles had been imported to Newcastle and Wilmington in the summer of 1801 by some vessels from Ireland, on board which a great many children died during the voyage; the epidemic at length reached Philadelphia and had become general throughout the city[1210]. At Whitehaven large numbers of infants were attended in measles from the Dispensary in 1796 and 1799, but the deaths (2 in 202 cases, and 2 in 266 cases) are probably only a few that came to the knowledge of the visiting physician. An epidemic at Uxbridge, Middlesex, in the winter of 1801-2 was certainly malignant or fatal more than ordinary, whatever its anomalous type may have meant.

The deaths in the London bills for the first twelve years of the century will be found in the table on p. 655. We find the measles deaths for the first time equalling the smallpox deaths in 1804, and in 1808 surpassing them, and we may take it that the deaths so entered were almost wholly of measles proper. The epidemic of measles in 1807-8 was, in fact, a great and clearly defined event in British epidemiology, the first of a series of epidemics in which that disease established not only its equality with smallpox as a cause of infantile deaths but even its supremacy over the latter. It would appear, also, to have been more malignant than the scarlatina that coexisted with it. Thus, Bateman, of London, at the outset of the great measles epidemic of 1807-8, says: “The most prominent acute disorders have been eruptive fevers and particularly the measles, which during October and November have been very prevalent, and, when occurring in young children, have proved very fatal by terminating in violent inflammation of the organs of respiration.... The scarlatina was generally mild, presenting the eruption with a slight sore-throat[1212].”

Other accounts of the epidemic in London show it to have been of the type which Sydenham, in 1674, called anomalous or malignant.

The epidemic began in October-November, 1807, and was remarked as unusually fatal[1213].

Besides these accounts for London, we have some details of the same epidemic at Edinburgh and Aberdeen and exact figures for Glasgow. It began at Edinburgh in the winter of 1807, and at Aberdeen (as at Glasgow) in the spring of 1808. At both places it was remarked as unusually fatal, chiefly from a complication of bowel complaint in children and from pulmonary affections in adults.

The observers at Edinburgh and Aberdeen agree that the epidemic was the worst that had been seen for many years. Says the former[1215]: “I believe that the present epidemic has been more general in this place and its vicinity than ever happened within the remembrance of any medical man at present living, and I am sorry to say it has been very fatal.” The Aberdeen chronicler says the mortality was “greater than we have witnessed for a long period,” and that the epidemic was general throughout the whole of England and Scotland. But, besides this direct testimony, there is a not less indirectly significant fact of the epidemic. It affected many adults—“persons of all ages, who had never had them,” says the Aberdeen writer: few persons escaped, says the Edinburgh observer, “who had been previously unaffected by this disease.” The deaths from pulmonic complaints did not often happen among children, but among people somewhat advanced in life. Significant also was the outbreak in the Invernessshire Militia, which marched into Edinburgh in March while the epidemic was raging. Fifty men, all young recruits newly joined, were attacked in the course of a few days, the others escaping the disease though equally exposed to it; in some of those who died in the regiment there were found, on opening the thorax, fibrinous pleurisy and pericarditis, with effusion of fluid, as well as evidences of bronchial catarrh[1216]. The Aberdeen writer says: “I always observed that in full-grown persons the eruptions were more numerous, quicker in appearing, and longer in going off than in young subjects.... Many full-grown persons were very ill, yet the measles were more fatal to the young.” The implication of so many adults in the severe epidemic of 1808 would of itself show that measles had not been for some time before a steady and universal affection of infancy and childhood[1217].

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.

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:

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.)

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.

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.”