Epidemiology

“ At the present moment, when the subject of epidemics is attracting so much attention, it may be interesting to call attention to the more important diseases comprised under that head, and to point out some of the main facts connected with their origin and distribution. {422} The principal epidemic diseases, then, are: small-pox, scarlet-fever, measles, typhus, relapsing fever, Oriental plague, yellow fever, diarrhoea, typhoid or enteric fever, cholera, dysentery, ague and remittent fevers, influenza, the sweating sickness, and the dancing mania. ”

“ Determining why susceptibility to a special disease in a particular case exists will constitute the greatest line of advance for the understanding and prevention of disease, and so the perfection of public health. In the last influenza epidemic countless physicians were puzzled by the spectacle of men and women in the pink of condition carried off in twenty-four hours while puny associates were either passed over, or pooh-poohed their colds. Pathologists have spent their energies fruitfully upon the infectious causes of disease, the microbes and parasites especially. ”

“ It is not pretended that the disease is always, or even, it may be, in the majority of cases, carried about by attendants; only that it is so carried in certain cases. That it may have local and epidemic causes, as well as that depending on personal transmission, is not disputed. Remember how small-pox often disappears from a community in spite of its contagious character, and the necessary exposure of many persons to those suffering from it; in both diseases contagion is only one of the coefficients of the disease. ”

“ When any large proportion are down at once, the doctors call it an epidemic, and it is attributed to a “wave”—an epizootic or influenza wave, for example, according as the victims are horses or men (the poor animals depend upon the elevated race for their habits, and never have disease except these are unphysiological) ,—when, in fact, the so-called epidemic, whether it be10 scarlet or yellow fever, diphtheria, or what not, is the result chiefly of the uniformly bad living habits of our people and their consequent predisposition to sickness. ”

“ The proper plan of stating the death-rate from a given disease is in terms of the population, or better still subdivided into death-rates from the disease for different age-groups as in the table on page 340, if the number of deaths is not too small to admit of this. The importance of stating the death-rate for different age-groups is greatest for such diseases as diarrhœa, whooping cough, and measles, in which most of the deaths occur at ages under five. ”

“ He was the first to recognize the specificity of the epidemic diseases, and argued from this that each disease must have a specific cause. "Just as a certain plant comes from the seed of the same plant and not from any plant at will, so each contagious disease must be propagated from a similar disease and cannot be the result of any other disease." Further he says, "It is necessary to assume that during the prevalence of an epidemic the contagious material undergoes an enormous increase, and this is compatible only with the assumption that it is a living substance." ”

“ Until recently the most reliable test of health rights not enforced was the number of cases of preventable, communicable, contagious, infectious, transmissible diseases, such as smallpox, typhoid fever, yellow fever, scarlet fever, diphtheria, measles, whooping cough. By noticing streets and houses where these diseases occurred, students learned a century ago that the darker and more congested the street the greater the prevalence of fevers and the greater the chance that one attacked would die. ”

“ Surely the places where dangerous infectious diseases are constantly propagated on a gigantic scale, and disseminated therefrom into the bodies of millions of animals and mankind, should be the very possible or probable source of epidemic disease. ”

“ For example, wherever, on the examination of these registries, deaths from fever or other epidemics were found to recur regularly, and in numbers closely clustered together, there will be found, on examination, to be some common and generally removable cause in active operation within the locality. Amongst whatsoever class of persons engaged in the same occupation deaths from one disease occur in disproportionately high numbers or at low ages, the cause of that disease will generally be found to be removable, and not essential to the occupation itself. ”

“ Every epidemic that sweeps through our communities is a testimony to the crying need of education in regard to such simple facts as the source of infectious material, the methods of its distribution, and the means of rendering it harmless.
PREVENTION IN INOCULATION. It has long been recognised that in most cases recovery from one attack of a contagious disease renders an individual more or less immune against a second attack. It is unusual for an individual to have the same contagious disease twice. ”

“ In all epidemics which increase to such a degree as to become contagious, it is of importance to distinguish which of these causes are the more powerful, the predisposing or epidemic causes, which originate the proneness to the disease, or the proximate causes, among which, in the generality of cases, contagion is the most prominent. ”

“ Examples are furnished in the small-pox, the plague, the measles, and, if we may include diseases not febrile, the leprosy, the itch, and the venereal disease. The latter, on the other hand, are not always in existence, they are called forth from nonentity by the causes of general diseases or epidemic constitutions, and they disappear again after the extinction of the epidemic diseases by which they were bred; they likewise vary in their development and their course in each particular epidemic. ”

“ A few brief observations on the control and prevention of infections diseases, such as small-pox, measles, scarlet fever, typhus fever, typhoid fever, cholera, &c.
The above-mentioned diseases are capable of being transmitted from those who are infected to those who are not. It is at once cheering and obligatory to know that the spread of these infectious diseases depends upon certain specific conditions, and that these conditions are primarily within the control of man. ”

“ Then material of all sorts began to come in for examination from the casualty clearing stations, field ambulances, sanitary and medical officers, rest stations and other places. Most of the routine bacteriological work proved to be of much the same nature as that done in a health laboratory at home, and [153] consisted of examinations to detect some of the ordinary communicable diseases such as diphtheria, cerebro-spinal meningitis, typhoid fever, malaria, dysentery, tuberculosis, and venereal diseases. ”

“ It is indeed extremely difficult, in view of the low level of development to which the science of Epidemics, in general no less than in particular, has as yet attained, to show this as applicable in any given case, more especially if it is a question of the epidemic condition of some disease of which the pathological relations themselves are far from being as yet adequately known. ”

“ The diseases which yielded a mortality under the average during the prevalence of the epidemic were diarrhœa and dysentery, liver disease, measles, scarlet fever, typhoid fever, and erysipelas. The death-rate of persons above twenty years old rose considerably above the average during the four or five weeks immediately preceding the beginning of the registration of deaths due to the epidemic. ”

“ Suppose, during the prevalence of a contagious epidemic, the authorities should content themselves with providing for those infected, and neglect to take the necessary steps to remove the cause of the disease by doing all that sanitary science indicated—they would soon be called to account for neglect of duty. ”

“ The Division of Scientific Research, as its name implies, is charged with studies of various diseases such as typhoid, malarial, typhus and yellow fevers, leprosy, tuberculosis, trachoma, pellagra, sanitation and hygiene, water supply and sewage and public health administration in states and cities in cooperation with the local authorities. ”

“ I need not refer again by detail to the statistics of mortality, but simply would say that if the diseases which produce some of the most deadly inroads into humanity, such as tuberculosis, measles, whooping cough, scarlet fever, diphtheria, croup and typhoid fever, are solely communicated to the individual from without, they are the diseases which the State must help the individual to avoid. ”

“ In a common source epidemic, as where members of a population contract a non-contagious disease from a poisoned well, the disease spreads only by exposure to the common source. If one eliminates the source, or closes the contaminated well, the epidemic is stopped. ”

“ In addition, establishing whether there is an increase or decrease in the incidence of a disease is a difficult problem well known to epidemiologists, who are used to considering factors such as ascertainment bias. ”

“ Under these circumstances the health is not, and cannot be, anything else than extremely good; the large number of old who are still robust and in employment, the experience and evidence of all the physicians who practise amongst the mill population, the result of the reports of the district physician, but above all, the healthy state they were in during several epidemics, and also the small proportion of deaths as seen in the parish register, all afford the most striking evidence of the fact of their healthiness. ”

“ The modern mind can readily imagine how much disease was bred through this utter disregard of the laws of hygiene. Epidemics, particularly of smallpox, occurred with appalling frequency, and even when there was no epidemic the death-rate was immense. ”

“ A medical institution, specialized institution or any of its staff member that discovers an infectious disease, an animal or a plant epidemic, or a disease cluster of unknown causes, shall promptly report it and take protective measures. ”

“ The nebulæ before Lord Ross's discovery were to the astronomer what the materies of epidemic and infectious disease are to medical men. In the absence however of a giant microscope to reveal such great truths, we may yet dimly shadow them by the light of our reason. It was predicted in 1849 that minute vegetable germs, in all probability all of the same type, were the agents producing epidemic and infectious disease. ”

“ What are the causes of Epidemic, Endemic, and Infectious Diseases? The occurrence of Epidemic Cholera last year in this country, awakened a spirit of enquiry. Where there is unrest, whatever may be the cause, there also is disquiet and discontent. ”

“ WHEREAS it is expedient to provide for the better prevention of the spread of dangerous epidemic disease; It is hereby enacted as follows:-
Short title, extent and commencement.
1. (1) This Act may be called the Epidemic Diseases Act, 1897.
(2) It extends to the whole of British India (inclusive of Upper Burma, British Baluchistan, the Santal Parganas and the Pargana of Spiti) ; and
(3) It shall come into force at once.
Power to take special measures and prescribe regulations as to dangerous epidemic disease. 2. ”

“ This epidemic Proteus is at once a great difficulty and a most instructive fact. It opens up the very old doctrine of “epidemic constitutions” of the air, which to many moderns savours of unscientific vagueness; and it brings us face to face with degrees or kinds of infectiveness which are, in matter of fact, more wonderful or more incomprehensible than the deadlier infections, such as the plague or Asiatic cholera. The most familiar instance of the kind is influenza. ”

“ At the present time the disease is more intelligently diagnosed, and while there is vast difference in the severity of the sickness, it is all the same thing. Of the ordinary cases, about 5 per cent terminate fatally; that is, in a village or a community where a hundred cases occur, there would be five deaths. If the epidemic, however, is of the severe form, a larger percentage of deaths occur, often reaching 20 per cent of those affected. ”

“ In many of the disciplines mentioned above, in which the epidemiological transition model has been most influential, investigators are primarily concerned with health writ large or all-cause mortality rather than individual diseases. ”

“ A number of cases of a so-called contagious dis-ease occurring about the same time in a community may be considered an epidemic by some. There is no established rule designating the percentage of individuals that must be affected by the same condition in order that an epidemic may be established. An endemic dis-ease may become epidemic at certain times of the year or when a greater number of people than usual become affected. A sporadic dis-ease may become epidemic when a greater number of people become affected. ”

“ Society seems to take a different attitude towards other contagious and infectious diseases, such as measles, chicken pox, diphtheria, etc. In these diseases, a physician has some responsibility toward society; he must report each case as it comes to his attention, to the Board of Health, who in turn assume some responsibility by isolating the disease. ”

“ For example, let it be assumed that in any given year 40 persons die out of 1600, which is in the proportion of 1 to 40, and in consequence of an unusual prevalence of measles, or some disease to which children are subject, the greater number of deaths occur amongst the infant portion of the population, and hence, out of the 40 deaths, 20 occur at 5 years of age, 10 at 25, and 10 at 60. ”