Virus

“ I had thus in the last days inoculated Joseph Meister with the most virulent virus, that of the dog strengthened by several passages from rabbits to rabbits; it was a virus that gave rabies after seven days of incubation to these animals, after eight or ten days to dogs. I was justified in venturing on this experiment by what had taken place with the fifty dogs of which I have spoken. When the state of immunity is reached, we can, without inconvenience, inoculate with the most virulent virus, and in any quantity ”

“ Probably both elements are active; as the relative immunity of the host rises the infectivity or virulence of the parasite must rise to an equal extent to maintain the equilibrium. If this were true we would find that in those localities in which the disease is endemic and where the population is relatively resistant there is a normally more virulent virus in existence. A stranger coming into such a community would, in view of his lower resistance to the virus, be more susceptible of becoming actively infected. ”

“ But in absolutely demonstrating, starting from the germ theory of disease as a basis, that disease could be guarded against, at least in certain cases, by inoculation with attenuated virus, he has opened the way probably for results the greatness of which we do not yet appreciate. ”

“ Clinical and epidemiologic investigations have yielded confirmatory evidence, and we are thus left with a conception of the virus of a given disease being distributed fairly widely throughout the world as an apparently harmless parasite on the human host, but taking on during epidemic periods a new and sinister role, only to relapse again into comparative quiescence as the epidemic subsides. ”

“ Up to the present about twenty diseases are known to be due to a filterable virus, and among these are some of the most important for animals and for man. Among the human diseases, yellow fever, poliomyelitis, and dengue are so produced; of the animal diseases in addition to foot and mouth disease, pleuropneumonia, cattle plague, African horse sickness, several diseases of fowls and the mosaic disease of the tobacco plant have all been shown to be due to a filterable virus. Of these organisms the largest is that which produces pleuropneumonia in cattle, and this alone has been cultivated. ”

“ As it is not the identical matter inserted which is absorbed into the constitution, but that which is, by some peculiar process in the animal economy, generated by it, is it not probable that different parts of the human body may prepare or modify the virus differently? ”

“ We observed such a universal distribution of influenza during the epidemic period that it is frequently assumed that all individuals are exposed to the disease, that the virus must enter the body of all or nearly all, and that it is due chiefly to a relative natural immunity that some do not fall victims. ”

“ For 102example, the July and autumn epidemic in England, as well as all occurring subsequent to them, would be due to a virus or several viruses which have been endemic in England since 1889, in fact since man has been in England, and the epidemics and their recurrences would be due to increase in the virulence of this local virus. The virus is distributed over the earth and may become virulent periodically in many countries at the same time, or if the periodicity is different on two continents the epidemics would occur at different times. ”

“ The possibility of such a method was suggested by the familiar observation, made by Pasteur and numerous other workers, that animals of different species differ widely in their susceptibility to various maladies, and that the virus of a given disease may become more and more virulent when passed through the systems of successive individuals of one species, and, contrariwise, less and less virulent when passed through the systems of successive individuals of another species. ”

“ I shall prove that the increase in the length of the periods of incubation of the rabies, communicated day after day to rabbits, as I have just said, to test the condition of virulence of our marrows, dried in contact with the air, is an effect of impoverishment in the quantity of the virus contained in the marrows, and not an effect of its impoverishment in virulence. ”

“ As a rule the virulence does not become so great as to cause a true pandemic, but at rare intervals, usually of decades, or thereabouts, the epidemic virus becomes so greatly enhanced, perhaps from passage to new territory and through non-immune individuals, that it eventually commences on its wild career around the earth. ”

“ Nevertheless, the tiniest particle of that virus introduced beneath the skin, either by injection or by abrasion, would certainly result in one of the most horrible and fatal diseases to which man is subject. ”

“ But it is obvious that, in the majority of cases, it must be impossible to decide by which of these channels the disease is conveyed, from the nature of the intercourse between the physician and the patient.
3. It is not pretended that the contagion of puerperal fever must always be followed by the disease. It is true of all contagious diseases that they frequently spare those who appear to be fully submitted to their influence. Even the vaccine virus, fresh from the subject, fails every day to produce its legitimate effect, though every precaution is taken to insure its action. ”

“ Serious as are the present effects of the virus that has stolen into our system, its malignant character and fatal tendency are apparent only to those who have made it the subject of a careful diagnosis. ”

“ The tissue cells are acted upon by increasingly active virus, each step of which acclimatizes the cells for the next stronger virus, until at length, when the virus formed by the micro-organisms introduced at the time of the bite comes to exert its action, the tissues have been so far altered or acclimatized that they can continue their work undisturbed in its presence ”

“ The remarkable feature is that for long periods of time the virus exists in the host in a quiescent state and only at intervals does it become highly invasive and thereby produces epidemics of greater or less extent. ”

“ When the germs of the virus mature in the living being, ready for reproduction in another person, they produce the acute contagious diseases, including small-pox, chicken-pox, scarlet fever, typhns fever, relapsing fever; measles, miliary fever, influenza, whooping-cough, and hydrophobia. ”

“ Almost invariably it will travel on to another locality, carried thither by human intercourse, and will there build again a local epidemiologic picture more or less modified by changes in the environment and changes in the virulence of the virus itself. ”

“ Once cured, they resist all inoculation which would be mortal for others. The oxygen of the air is manifestly the transformer of this virulent virus into vaccine virus; for, if the virulent blood or cultivations remain inclosed in their tubes, sealed from all entrance of the air, they retain not only for some hours, but for months, their life and their original virulence. ”

“ As with most virus diseases there is a transitory leukopenia—a drop in the total number of white blood cells—and a rise in temperature of about two or three degrees. As the virus attacks the alveolar structures, the temperature rises and the white blood cell count becomes elevated. The lungs become inflamed and painful. There is a considerable quantity of lymphoid exudate and pleural effusion. Secondary invaders and pus-forming bacteria follow the viral destruction of the lung tissue and form abscesses. Breathing becomes progressively more difficult as more lung tissue is destroyed. ”

“ The vaccination in small-pox is an inoculation of the virus of the disease; the rabies inoculation is a transmission of the vital products of the disease attenuated; the plague and cholera vaccinations are inoculations of pure cultures of living virus from outside the body. ”

“ Wenyon found that the virus would not pass through the unabraded skin.
The disease is most prevalent about the end of summer and in the autumn. It is a disease of towns. Some have thought that it might be transmitted through the medium of the laundry. Not only can man be infected by inoculation but this is also possible with monkeys and dogs when a scarified area about nose or over eyebrows is inoculated with virus from a sore. ”

“ The energy or the nature of the virus varies in each species of animals. By passing the virus through different animals, ‘cultures,’ or varying qualities of virus, are obtained, whose precise effects can be predicted. Thus a ‘culture’ has been obtained which certainly kills a rabbit in five or six days, and another which certainly kills a guinea-pig in the same time. ”

“ To seek to lessen the virulence by rational means would be to establish, upon an experimental basis, the hope of preparing from an active virus, easily cultivated either in the human or animal body, a vaccine-virus of restrained development capable of preventing the fatal effects of the former. Therefore, we have applied all our energies to investigate the possible generalizing action of atmospheric oxygen in the attenuation of virus. ”

“ The culture of the virus heightens its maleficent properties. This gradual increase of the virulent force is such that, if we take a drop of blood from an animal representing the twenty-fifth term in a series of successive inoculations, and so dilute this drop with water that a drop of the dilution corresponds to one trillionth of the original drop, we get a liquid of which the smallest quantity still displays mortal activity. ”

“ This contagion is beyond question a living something which multiplies with great rapidity under proper conditions, and, escaping from the bodies of those infected with the disease, in one way or another, reaches other individuals. It is beyond question true that the virus passes from the body of those infected by means of the urine and feces, and it [Pg 189] is likely that the secretions from the mouth and nose frequently contain the germs that cause the fever. ”

“ In honor of Jenner, who was the first to discover the way of preparing a virus of a fixed strength safe to be used for the preventive treatment of men, Pasteur proposed that all such artificially bred, so to say, domesticated forms of microbes be called vaccines, while the word virus be reserved for a contagion growing in nature in a natural condition, or taken direct from an infected individual. ”

“ He laid hold of the murderous virus of splenic fever, and succeeded in rendering it, not only harmless to life, but a sure protection against the virus in its most concentrated form. No man, in my opinion, can work at these subjects so rapidly as Pasteur without falling into errors of detail. ”

“ Attenuation of the virulence can be obtained by introducing into the blood and tissues some product either interfering with the full development of the parasite or modifying the tissues and fluids of the body so as to increase their resistance to the extension of the parasite or to its products. This seems to be the chief principle at the root of Pasteur's vaccination for hydrophobia, etc. (c) Neutralizing the physiological action of the virus by using its physiological antagonist. ”

“ The virus of a cursing creed is rendered comparatively harmless by the time it reaches the young sinner in the nursery. Its effects fall as far short of what might have been expected from its virulence as the pearly vaccine vesicle falls short of the terrors of the confluent small-pox. ”

“ In a similar manner a particle of contagium spreads through the human body, and may be so multiplied as to strike down whole populations. Consider the effect produced upon the system by a microscopic quantity of the virus of smallpox. That virus is to all intents and purposes a seed. It is sown as leaven is sown, it grows and multiplies as leaven grows and multiplies, and it always reproduces itself....Contagia are living things, which demand certain elements of life, just as inexorably as trees, or wheat, or barley ”

“ The migration reduces the viral presence in other parts of the body, with a corresponding diminution in physical manifestations of the disease. The virus, however, thrives in the lymph nodes, which, as a vital point of the body's immune response system, represents an ideal environment for the infection of other CD4‘ cells. ”

“ Almost all practical preventive measures in this country and on the Continent as regards cholera and other infectious maladies are based on the assumption—supported by a good deal of evidence both theoretical and practical—that the virus is particulate, and, as indicated by its self-multiplication within the affected person, is a living organism. ”

“ Each infections disease is caused by a district type of germ and virus which is too small to be seen with human eye, but can be seen with the help of a powerful microscope. An Infection disease becomes a community problem because its prevention and control require the team work of health workers and community. ”

“ The most advanced medical scientists may be found in this part of the world trying to find out something definite about the virus and devising means for its eradication, but are as yet in the dark concerning how to combat the suffering and fatalities that follow in the wake of this strange disease. ”

“ Using such technologies, which have been utilized to investigate Ebola, pandemic flu, influenza, hanta viruses, lassa, rabies, and Marburg viruses, there is no need for a bioweaponeer to isolate the virus from an infected patient, acquire it from a germ bank, or culture it from nature. ”

“ Questions multiply as the facts relating to the attenuation of a virus suggest inductions, awaken ideas, and throw new lights upon a problem which, until within these last few years, has remained so obscure. ”

“ It is not communicable by the sick to the healthy. Although transportable in the hemp to a very slight extent, it is only in limited spots here and there in the endemic districts that the virus originates. ”