Pathogenesis

“ Any cause that lowers the vitality by depressing the [Pg 12] system, reduces the resistance to bacteria and is therefore apt to favor their growth. Exhausting diseases such as anemia, obesity, alcoholism, diabetes, fatigue, or even exposure to cold, are instances. Germ growth is also favored by the presence of dead, or injured tissues, of blood clots, of foreign substances, and above all, by the presence of some of the substances in which the germ has already been growing at the time of its inoculation, and containing some of its toxins. ”

“ Since the cells created are formed of bacteria, that is to say, of vital germs, as the body tissues are of cells, the destruction of the tissues and cells of necessity sets bacteria free; these therefore are not in reality the cause, but the result of disease.
Febrile, or Positive Diseases.
In pronounced inflammation the disturbance of the electrons, the heat, apart from the functional irregularities which occur in systemic processes, is diffused through the entire body: the sickness becomes fever. The blood is impelled with increased pressure throughout the whole body. ”

“ This enormous mass of disease furnishes ample material for infection on every side. A most infinitesimal germ, invisible, impalpable, would suffice to infect a single human body, and that body might suffice to infect very many others. ”

“ Methods of fighting Germ Diseases.—As we have seen, diseases produced by bacteria may be caused by the bacteria being directly transferred from one person to another, or the disease may obtain a foothold in the body from food, water, or by taking them into the blood through a cut or a wound or a body opening.
It is evident that as individuals we may each do something to prevent the spread of germ diseases, especially in our homes. We may keep our bodies, especially our hands and faces, clean. ”

“ It is New Conceptions of Etiology. proper to point out here how intimately a pathology thus regenerated modified current conceptions of disease, in the linking of disease to oscillations of health, and the regarding many diseases as modifications of the normal set up by the impingement of external causes; not a few of which indeed may be generated within the body itself—“autogenetic poisoning.” The appreciation of such modifications, and of the working of such causes, has been facilitated greatly by the light thrown upon normal processes by advances in physiology ”

“ The 'Germ Theory,' briefly stated, is this. There are all around us millions of micro-organisms, parasites which thrive and grow by feeding upon the animal world. In proportion as these parasities infest, and thrive upon a given individual, so will that individual become diseased, and it has been shown that in many cases a special germ will cause a special disease. I could deliver you a lecture, hours long, upon the classification, morphology, and pathogenic action of bacteria, but I wish at present to lead your mind into a different channel. ”

“ For the extension of infection from one individual to another the infecting organisms must in some way be transferred. The most important of the conditions influencing this are the localization of the disease and the character of the infectious organisms, particularly with regard to their resistance to the conditions met with outside of the body. The seat of disease influences the discharge of organisms; thus, if the disease involve any of the surfaces the organisms become mingled with the secretions of the surface and are discharged with these. ”

“ The practice of medicine in the past has been directed towards the curing of developed disease and physical ailments. The practice of medicine in the future is to be along the line of preventive practice. Science is showing us how to prevent infection. Science is fighting the deadly microbe which comes to us in the air we breathe, the water we drink, and the food we eat and the infected things we touch.
Nature has supplied the human body with a home guard of necessary bacteria and in the circulation system are phagocytes which fight the invading microbes and generally destroy them. ”

“ Here I shall only observe, that were the reverse true, then the contagious matter must pass through every gland, and every portion of the human form, in as much as the blood circulates in every point; and, therefore, every spot should become diseased, and every part, in the same circumstances, should become diseased at the same moment126. Disease is not spread in the living system mechanically, by the absorption of matter, which is conveyed over the whole body, but by the sympathetic connection of parts, which has been already explained, and which will afterwards be farther illustrated. ”

“ The small quantity of diseased organic matter originally introduced into the system by absorption, acts as a ferment and reproduces itself in the mass of the blood, until this becomes unfitted for the performance of its functions and the animal is killed; the active principle being thus copiously present, is exuded from the skin and lungs and gives a contagious character to the disease, or it remains only in the blood, or is secreted in pustules, constituting infection, by which the disease may be communicated to some other person. ”

“ I desire now to refer again to the subject of racial and species immunity for which the humoral factors of bacterial destruction afforded an imperfect explanation, in order that I may point out that the introduction of bacteria, incapable of causing infection, into immune species is followed by immediate phagocytic ingestion and destruction of the microorganisms. The rapidity and perfection of the phagocytic reaction in insusceptible animals are very impressive and might readily lead to the decision that they suffice to explain the resistance or immunity. ”

“ Permeating the whole organism, they give rise to such diseases as fever, Sarvangaroga, etc. which invade the entire system. The aggravated and expanded humours, thus firmly ensconced in the different parts of the body, exhibit the premonitory symptoms of diseases which will be fully dealt with under their respective heads. The manifestation of these premonitory symptoms should be considered as the fourth occasion for medical treatment.
Disease-Its Development:—Now we shall deal with the full development or manifestation of a disease. ”

“ What we call an infection is the invasion of the body from the outside by minute living organisms, either plant or animal, and the establishing of them within the body, so that they grow and multiply. They carry on their metabolism just as do all other living cells and produce various chemical products as a result. There are many organisms living within our bodies whose metabolic products apparently do us no harm, and so we serve as hosts for these unbidden guests year in and year out without even knowing of their existence. ”

“ George N. Kreider, of Springfield, 111., micro-organisms enter the body first by the skin through lesions, openings of the sweat-pores, or sebaceous ducts, or by the sides of the hairs; and, secondly, by the mucous membrane through lesions of the membrane, openings of the ducts or follicles, or pockets, sulci, or folds. There are also localized infections, originating in a manner as yet unknown, and giving rise to certain violent diseases; and universal infections, giving rise to hereditary transmissible disease. ”

“ COLDS, CONSUMPTION, AND PNEUMONIA
Disease Germs. In all foul air there are scores of different kinds of germs—many of them comparatively harmless, like the yeasts, the moulds, the germs that sour milk, and the bacteria that cause dead plants and animals to decay. But among them there are a dozen or more kinds which have gained the power of living in, and attacking, the human body. In so doing, they usually produce disease, and hence are known as disease germs. ”

“ We have now reached a phase of this question when it is of the very last importance that light should once for all be thrown upon the manner in which contagious and infectious diseases take root and spread. To this end the action of various ferments upon the organs and tissues of the living body must be studied; the habitat of each special organism concerned in the production of each specific disease must be determined, and the mode by which its germs are spread abroad as sources of further infection. ”

“ I have said that our knowledge in this direction has, even in the last two or three years, made enormous strides, and it is now almost a matter of certainty that all contagious or infectious disorders, as well as many others, are but the expression of the fact that minute living bodies have made a resting-place for themselves in or upon other living tissues; and that the development of the phenomena of these morbid states is but an indication of their presence and reproductive activity—either as cause, or as an accompaniment of these disease manifestations. ”

“ In view of the need for pathologic material in undergraduate and graduate education, the Committee on Pathology of the National Research Council urges that all who have suitable anatomic specimens forward them to the Curator of the Army Medical Museum * * * for correlation and distribution to other central agencies and to teaching institutions. Material from the following is particularly wanted: the malarial diseases, bacillary dysentery, endamebiasis, filariasis, the trypanosomiases, the relapsing levers, the leishmaniases, the rickettsial diseases, yellow fever, cholera, plague, and yaws. ”

“ But the poisonous action of most of the pathogenic bacteria is due to the chemical products secreted by the organisms, and it is to the circulation and absorption within the body of these poisons that the disturbances of the animal system, which characterise disease, decay, and dissolution of every organism, must be traced. ”

“ Ordinary cleanliness, good vitality, clean blood and tissues, the organs of elimination in good, active condition and, last but not least, a positive, fearless attitude of mind will practically establish natural immunity to the inroads and ravages of bacteria and disease taints. If infection takes place, the organism reacts to it through inflammatory processes, and by means of these endeavors to overcome and eliminate microorganisms and poisons from the system. ”

“ In the various reactions of the tissues against the exciting cause of the injury we see a striking example of a beautifully organized plan of attack and defence on the part of the organism.
In some of the infective conditions the conflict fortifies the organism against future attacks of the same nature, as for example in the immunity following many of the acute infective diseases. This acquired immunity is brought about by the development of a protective body as a result of the struggle of the cells and fluids of the body with the invading bacteria and their toxins. ”

“ From the facts here given it will be seen that the individual's susceptibility to disease produced by parasitic bacteria will depend upon his habits of cleanliness, his care in handling infectious material, or care in cleansing the hands after such handling, upon his habit of eating food cooked or raw, and upon the condition of his skin and mucous membranes, since any kind of bruises will increase susceptibility. ”

“ Where no fetters are placed on the economic life, the healthy organism, in time, overcomes these local inflammations, as we may designate, by an expression taken from pathology, the influx of an abnormal number of cells of a certain sort to a place not intended for them. ”

“ There are, for example, many diseases of the digestive, nutritive, and excretory systems, of the heart and arteries, of the brain and nerves, and various less clearly localized abnormal conditions, that owe their origin to inherent defects of the organism, or to various indiscretions of food or drink, to unhygienic surroundings, to material injuries, or to other forms of environmental stress quite dissociated from the action of bacteria. ”

“ Late investigations seem to show that one of the functions of the white corpuscles of the blood is to devour disease-germs and bacteria present in the circulation,—thus absorbing these organisms into subjection to the central life of the body,—and that for this object they congregate in numbers toward any part of the body which is wounded or diseased. ”

“ While no intelligent student at present denies that the infectious diseases—of which the above named are but a very few—are the result of the introduction into the body, from without, of minute living organisms, for the most part vegetable,—thus constituting them in reality, as they are often called, parasitic diseases,—but few are so familiar with318 the history of modern discovery as to appreciate the basis upon which it has been demonstrated. The proof of the germ origin of disease is the legitimate outcome of the discovery of the actual causes of fermentation and putrefaction. ”

“ Preventive medicine is telling us how to destroy those thus lying in wait for a chance of infection, by discovering disinfectants and telling us especially where and when to use them. It has already taught us how to crush out certain forms of epidemics by the proper means of destroying bacteria, and is lessening the dangers from contagious diseases. In short, the study of bacteriology has brought us into a condition where we are no longer helpless in the presence of a raging epidemic. ”

“ Clinical observation has been employed to confirm or refute the conclusions of experimental pathology, and has clearly demonstrated that the poisonous processes, of which we have spoken, can begin in the human body and proceed without the presence of bacteria, and that bacteria may be present in large quantities without the slightest symptom of any poisonous complication. ”