The Commissioners repeatedly call attention to the fact that the mortality from measles has not at all declined and that other zymotics have not declined in the same proportion as small-pox, and they argue: “If improved sanitary conditions were the cause of small-pox becoming less, we should expect to see that they had exercised a similar influence over almost all other diseases. Why should they not produce the same effect in the case of measles, scarlet fever, whooping-cough, and indeed any disease spread by contagion or infection and from which recovery was possible?” This seems a most extraordinary position to be taken in view of the well-known disappearance of various diseases at different epochs. Why did leprosy almost disappear from England at so early a period and plague later on? Surely to some improved conditions of health. The Commissioners do not, and we may presume cannot, tell us why measles, of all the zymotic diseases, has rather increased than diminished during the whole of this century. Many students of epidemics hold that certain diseases are liable to replace each other, as suggested by Dr. Watt, of Glasgow, in the case of measles and small-pox. Dr. Farr, the great medical statistician, adopted this view. In his Annual Report to the Registrar-General in 1872 (p. 224), he says: “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.” This last remark is very suggestive in view of the modern germ-theory of these diseases. This substitution theory is adopted by Dr. Creighton, who in his History of Epidemics in England suggests that plague was replaced by typhus fever and small-pox; and, later on, measles, which was insignificant before the middle of the seventeenth century, began to replace the latter disease. In order to show the actual state of the mortality from these diseases during the epoch of registration, I have prepared a [diagram (II.)] giving the death-rates for London of five of the chief zymotics, from the returns of the Registrar-General, under the headings he adopted down to 1868—for to divide fevers into three kinds for half the period, and to separate scarlatina and diphtheria, as first done in 1859, would prevent any useful comparison from being made.
The lowest line, as in the larger diagram, shows Small-pox. Above it is Measles, which keeps on the whole a very level course, showing, however, the high middle period of the zymotics and two low periods, from 1869 to 1876, and from 1848 to 1856, the first nearly corresponding to the very high small-pox death-rate from 1870 to 1881; and the other just following the two small-pox epidemics of 1844 and 1848, thus supporting the view that it is in process of replacing that disease. Scarlatina and diphtheria show the high rate of zymotics generally from 1848 to 1870, with a large though irregular decline subsequently. Whooping-cough shows a nearly level course to 1882 and then a well-marked decline. Fevers (typhus, enteric, and simple) show the usual high middle period, but with an earlier and more continuous decline than any of the other zymotic diseases. We thus see that all these diseases exhibit common features though in very different degrees, all indicating the action of general causes, some of which it is by no means difficult to point out.
In 1845 began the great development of our railway system, and with it the rapid growth of London, from a population of two millions in 1844 to one of four millions in 1884. This rapid growth of population was at first accompanied with overcrowding, and as no adequate measures of sanitation were then provided the conditions were prepared for that, increase of zymotic disease which constitutes so remarkable a feature of the London death-rates between 1848 and 1866. But at the latter date commenced a considerable decline both in the total mortality and in that from all the zymotic diseases, except measles and small-pox, but more especially in fevers and diphtheria, and this decrease is equally well explained by the completion, in 1865, of that gigantic work, the main drainage of London. The last marked decline in small-pox, in fevers, and to a less marked degree in whooping-cough, is coincident with a recognition of the fact that hospitals are themselves often centres of contagion, and the establishment of floating hospitals for London cases of small-pox. Perhaps even more beneficial was the modern system of excluding sewer-gas from houses.
We thus see that the increase or decrease of the chief zymotic diseases in London during the period of registration, is clearly connected with adverse or favourable hygienic conditions of a definite kind. During the greater part of this period small-pox and measles alone showed no marked increase or decrease, indicating that the special measures affecting them had not been put in practice, till ten years back the adoption of an effective system of isolation in the case of small-pox has been followed by such marked results wherever it has been adopted as to show that this is the one method yet tried that has produced any large and unmistakable effect, thus confirming the experience of the town of Leicester, which will be referred to later on.
The Commissioners in their Final Report lay the greatest stress on the decline of small-pox at the beginning of the century, which “followed upon the introduction of vaccination,” both in England, in Western Europe, and in the United States. They declare that “there is no proof that sanitary improvements were the main cause of the decline of small-pox,” and that “no evidence is forthcoming to show that during the first quarter of the nineteenth century these improvements differentiated that quarter from the last quarter or half of the preceding century in any way at all comparable to the extent of the differentiation in respect to small-pox” (p. 19 par. 79). To the accuracy of these statements I demur in the strongest manner. There is proof that sanitary improvements were the main cause of this decline of small-pox early in the century, viz., that the other zymotic diseases as a whole showed a simultaneous decline to a nearly equal amount, while the general death-rate showed a decline to a much greater amount, both admittedly due to improved hygienic conditions, since there is no other known cause of the diminution of disease; and that the Commissioners altogether ignore these two facts affords, to my mind, a convincing proof of their incapacity to deal with this great statistical question. And, as to the second point, I maintain that there is ample direct evidence, for those who look for it, of great improvements in the hygienic conditions of London quite adequate to account for the great decline in the general mortality, and therefore equally adequate to account for the lesser declines in zymotic diseases and in small-pox, both of which began in the last century, and only became somewhat intensified in the first quarter of the present century, to be followed twenty years later by a complete check or even a partial rise. This rise was equally marked in small-pox as in the other diseases, and thus proved, as clearly as anything can be proved, that its decline and fluctuations are in no way dependent on vaccination, but are due to causes of the very same general nature as in the case of other diseases.
To give the evidence for this improvement in London hygiene would, however, break the continuity of the discussion as to small-pox and vaccination; but the comparison of the general and zymotic death-rates with that of small-pox exhibits so clearly the identity of the causes which have acted upon them all as to render the detailed examination of the various improved conditions that led to the diminished mortality unnecessary. The diagram showing the death-rates from these three causes of itself furnishes a complete refutation of the Commissioners’ argument. The evidence as to the nature of the improved conditions will be given in another work to be published shortly.
Small-pox and other Diseases in Britain during the Period of Registration
We have no general statistics of mortality in England and Wales till the establishment of the Registration system in 1838, but the results make up for their limited duration by their superior accuracy. Till the year 1870 no record was kept of the amount of vaccination except as performed by the public vaccinators, but since 1872 all vaccinations are recorded, and the numbers published by the Local Government Board. My [third diagram] is for the purpose of showing graphically the relation of small-pox to other zymotic diseases, and to vaccination, for England and Wales. The lower line shows small-pox, the middle one zymotic diseases, and the upper the total death-rates. The relations of the three are much the same as in the London diagram, the beginning of the great decline of zymotics being in 1871, and that of small-pox in 1872, but the line of small-pox is much lower, and zymotics somewhat lower than in London, due to a larger proportion of the inhabitants living under comparatively healthy rural conditions.
But if the amount of vaccination were the main and almost exclusive factor in determining the amount of small-pox, there ought to be little or no difference between London and the country. But here, as in all other cases, the great factor of comparative density of population in compared areas is seen to have its full effect on small-pox mortality as in that of all other zymotic diseases.
This non-relation between vaccination and small-pox mortality is further proved by the thick dotted line showing the vaccinations per cent. of births for the last 22 years, as given in the “Final Report” (p. 34). The diminution of vaccination in various parts of the country began about 1884, and from 1886 has been continuous and rapid, and it is during this very period that small-pox has been continuously less in amount than has ever been known before. Both in the relation of London small-pox to that of the whole country, and in the relation of small-pox to vaccination, we find proof of the total inefficacy of that operation.