Volume 2

A treatise on hygiene and public health / edited by Thomas Stevenson and Shirley F. Murphy.

Date:
1892-1894
Catalogue details

Licence: Public Domain Mark

Credit: A treatise on hygiene and public health / edited by Thomas Stevenson and Shirley F. Murphy. Source: Wellcome Collection.

    19/1058 (page 3)
    INTEODUCTION Few branches of medical science can be said to have received, within the last tweuty-flve years, greater attention, and to have developed more largely within a comparatively short period, than the knowledge of the nature of infectious diseases. Not only have many disorders, belonging to this class and for a long time suspected as belonging to this group, become well under- stood in their nature, their mode of origin and spread, but others, not previously suspected to be communicable diseases at all, have been shown to appertain to this class. To quote for each of these one instance : typhoid fever, though for a long time assumed to be a communicable disorder spread- ing from the sick to the healthy by the evacuations, had not, prior to the researches of Budd, Snow, Simon, Buchanan and others, been proved to be of this character, and though some authorities, like Murchison, pleaded for the possibility of a spontaneous origin, the weight of evidence was in favour of its being a specific disease, which, hke all specific diseases, can only arise from a previous specific disorder of the same kind. By the researches of more modern investigators, notably Buchanan, Ballard, and Thorne Thorne, its mode of spread has become well understood, and by their investigations its nature—viz. that of a specific communicable disease—been definitely settled. As examples of diseases not previously suspected to belong to this group but now known to be so, we may quote tetanus, and epidemic or croupous pneu- monia. Of both these diseases recent research has shown that they are of an infectious character, that m both there exists a specific virus which, finding entrance into a healthy individual, is capable of setting up the disorder. These examples we could easily multiply. Nay more, we could show, on the one hand, that as regards a number of disorders for whose specific nature there existed until quite recently very slender evidence, there are now definite and exact experimental grounds for asserting their specific nature, e.g. anthrax, tuberculosis, septicaemia, and erysipelas; on the other hand, by ascertaining the exact nature of some of these disorders, others formerly not distinguished from them have been shown to have a separate existence and to be different from them in their pathology, symptoms, course, and causation. Thus, for instance, malignant anthrax has been shown to be a perfectly separate disorder from symptomatic anthrax ; woolsorters' disease (malignant pustule) to be a separate disease from some forms of ragsorters' disease ; tuber- culosis to be different from other chronic lung diseases, to which it bears a distant pathological semblance. These results have been achieved by the isolation and study of the essence of these diseases—the contagium, which was shown to be a living microphyte,' contagium vivum, differing as regards morpliology and biology in the different diseases to which it gives rise. It is no doubt an interesting study to .trace the history and the development of the theory of the contagium vivum; but at the present day such a study is chiefly of an historical mterest, and not an ' fiiKpdsi small, (pirif, plant. P 2