EPIDEMIC DISEASES.

New Zealand Times, Volume XXXII, Issue 4998, 31 March 1877, Page 1 (Supplement)

EPIDEMIC DISEASES.

Mr. Netteu Eadcliffe, the president of the Epidemiological Society of London, recently opened the session of the society by an address on “ The Present Position of Epidemiological Science.” He commenced by reminding his hearers of the line of argument which he had pursued on the same occasion last year, when he pointed out that the writings of Sir William Jenner, following the investigations of Dr. A. P. Stewart, and followed by those of Dr. Murchison, had, madeknown the difference between varieties of fever which had previously been confounded together, and had formed the starting-point of, a new era in the exact investigation of disease. As long as maladies which vyere' essentially different, whether as regards their causes, their course, or their termination, remained undistinguished from each other, no real progress could be made in the work of preventing any of them; and even the simplest questions connected with their several modes of diffusion remained insoluble. The discrimination of typhus fever from typhoid, said Mr. Eadcliffe, brought medicine from a seventh heaven of meaningless verbiage, into which it had gone astray, back to the true startingpoint of all epidemiological knowledge—investigation at the bedside—and recalled epidemiology from the outer spheres of semi-mystical speculation to the more moderate compass of a hospital ward or a bedroom, thus substituting for the cosmos a common bedstead.

Mr. Eadcliffe then proceeded to speak of the way in which the farther increase of exact knowledge about epidemics and “ epidemicity” was hindered by the survival of “ certain tricks of language which we have inherited from the earlier days of physic.” Among these' he mentioned the uncertainty of meaning with which even the word “epidemic” itself was used, and then the retention in scientific language of such phrases as “epidemic constitution,” epidemic influences,” and the like. The continued use of these terms, promiscuously accordant with the technical significations now ordinarily assigned to them in the same text-books which contain the results of investigations pursued on the method used by Stewart, Jonner, and Murchison in the study of continued fevers was, he Said, indescribably incongruous. It could only be possible in, and was indicative of, a transition state of epidemiological science. The use of the word epidemic itself was probably a necessity of medicine; but it should be used only in its common and natural sense to signify “ common to, or affecting a whole people, or a great number in a community; prevalent, generaland all mystical notions with regard to it should be wholly laid aside. As Dr. Leon Colin had lately said, “ It is the disease that constitutes the epidemic, and not the epidemic the disease. The evil always remains the same, the number of those affected being alone increased.” The first element in the successful prosecution of epidemiological research, in this view of the question, is the

study of the several diseases which are liable to become epidemic, and of the conditions upon which their greater or less prevalence depends. In one sense this may be said to be a truism ; but it can baldly be so regarded while our text-books are still defaced by usages of the word epidemic, which—again to quote Dx-. Leon Colin—“signify implicitly a common cause, apparently undecomposable, to which individuals are not exposed successively, but simultaneously—a something isolated, impersonal, inaccessible to reason, detached from the disease itself, the epidemic genus, constitution, influence—a creative force of the different epidemic affections, compelling, directing, extinguishing them.” After glancing at the manner in which the study of the several fevers individually, instead of in groups, had tended to banish tlxe class of errors which he was condemning, Mr. Badcliffe proceeded further to illustrate his position by the recent history of small-pox, which would, he said, display the amazing fertility of that kind of epidemiological research which starts from a study of a disease itself and of its habits. The epidemic small-pox of 1870-73 in this country, according to Dr. Seaton, was part of a world-wide diffusion, marked wherever it oo-oux-red by an intensity and malignity unequalled by any pi'evious epidemic- within living memory. In every country attacked, so far as our information extends, the peculiar intensity was manifested by the extreme diffusiveness of the disease, by its attacking an unusual number of persons who were regarded as protected against it either by previous small-pox or by vaccination, and by the occurrence with quite remarkable frequency of cases of a malignant and haemorrhagic type, and a consequent unusually high ratio of deaths to attacks. There is a general concurrenoe of testimony that these peculiar characters were first observed in France towards the close of 1869, and that, irrespective of the continuous prevalence of small-pox among all civilised and {nasi-oivilised communities, the malady spread fx-om France throughout the world. Hei-e, then, was an example of a great epidemic, x-ecalling the violence of those which preceded the epoch of vaccination, and recurring in this form after a long interval. The facts bearing upon the question have been made the subject of careful study by Dr. Leon Colin, and his results tend to prove that the beginning, development, and diffusion of the epidemic are fully explicable or well-known characteristics of the disease, without calling to aid any general undetermined or undeterminable agency. He shows that the great outbreak of smallpox in France in 1869 had been preceded by an unaccustomed and growing prevalence during several years ; that the commencement of the epidemic spread occurred in Brittany among a population practically unprotected by vaccination; that there the disease first declared itself in the virulent form manifesting the characters which particularly distinguished the subsequent diffusion. The outbreak in Brittany, as it chanced, was in active progress when the great movement of troops began in France which were called for by the war with Germany, and when the active recruiting rendered necessary by the war came into operation. The exigencies of the period put a stop to the practice of vaccination and re-vaccination, which is customary for recruits entering the French army. ’ The virulent small-pox which had appeared in Brittany spread to the troops in that province, and found among them a large mass of unprotected persons, among whom it spread unmodified. These troops carried the disease with them in their subsequent movements, conveying it to other forces and to the various communities with which they came in contact. Thus the contagion spread to the armies in the field, and by them was scattered over the various districts occupied during the war. In Paris the phenomenon was seen of the virulent form of the disease, first observed in Brittany, being introduced among the population during the progress of a milder local epidemic, and in the course of the siege displacing, so to speak, the original form of the malady. From France the movements of the virulent form of smallpox have been clearly traced, and they show that country to have been the centre and starting-point of the diffusion. V ithout following Dr. Colin through all the points of his researches, Dr. Badcliffe dwelt upon the importance of the suggestion that the activity of an infectious disease might be increased by an increase in the, power of its virus, and he showed how completely this view, was in harmony with the : recent researches by which Dr. Burdon-Sanderson has proved that the common infective products of lesions caused by putrifying animal matters or by purely chytnical agency may be artificially cultivated so as to furnish, in the words of Mr. Simon, one of the most tremendous morbid poisons which the mind of the pathologist can conceive. He applied the considerations hence arising to the facts of scarlet fever and of cholera, and suggested that the severity of an epidemic, instead of being determined by the condition of the persons exposed to the poisonous influence, might be regarded, with much probability, as being at least to some extent governed by variations in the intensity of the poisonous influence itself. The possible overlapping of a previously existing mild epidemic by an imported one of the same kind, but of greater severity, as seemed to have been the case in Paris, was also considered, as well as the influence, believed by Dr. Colin to be considerable, of certain meteorological changes which may occur iu wider cycles than those of the ordinary terrestial seasons, such, for example, as the sun-spot periods. In the observation of such periods, epidemiologists would be lifted altogether out of the merely vague notions about planetary or telluric influences by which their science had formerly been de-; faced.

Turning next to another aspect of epidemiological science, Mr. Eadcliffe noted that some of the more important questions connected with it had lately been brought within the scope of systematic laboratory experiment. Such researches date, in this country, from the investigations of Drs. Beaie and Burdon-Sanderson into the contagion of cattle plague ; and they are of two kinds -physiological and chymical. He gave some account of the objects and scope of both these kinds, and showed how they would ultimately come to bear upon the question whether the poisons which cause epidemics can be produced anew by the recurrence of the conditions which first produced them, or whether they are always to be looked upon as the offspring of pre-existing causes. In respect of the chymical branch of the work, he quoted Mr. Simon with regard to its nature and ten. dency ; and concluded by declaring the true method by which the epidemiological science was renovated a quarter of a century ago is in lusty and increasingly vigorous life, although certain shreds and patches of old and effete doctrines still adhere to it, somewhat hampering its progress, and somewhat defacing its symmetry.