Infectious disease

“ The word infection is applied to the vehicle by which a malady is transmitted from one person to another by the air, and with or without actual contact. The type of infectious disease is small-pox, and this is also, as is well-known, a highly contagious complaint. Scarlet-fever, measles, whooping-cough, mumps, etc., are likewise both contagious and infectious, and make up the class of disorders popularly known as diseases which are "catching." ”

“ We know that the agents responsible for infectious diseases are specific minute organisms which must be present in the system to produce the disease in question, and that these micro-organisms are conveyed from place to place by infected persons, by intermediaries, on articles to which they have attached themselves, in contaminated food, in drinking-water, and in many other ways. ”

“ Now we know that many diseases called infectious are caused by micro-organisms, and we group others under this class because we hold theoretically that they have their origin in microbes not yet isolated. Hence we define an infectious disease as one which is caused by a living pathogenic micro-organism, which enters the tissues from without, and is capable of multiplying therein. These micro-organisms have a time of incubation during which a poison is made in the tissues, and this brings about the intoxication we call the disease. ”

“ 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. ”

“ 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. ”

“ Every infectious disease is now held to be due to its own particular micro-organism, and many diseases that were not until recently thought to be infectious are now classed as such because they have been proved to be caused by living germs. Conspicuous among these diseases is pulmonary consumption. ”

“ Cold and moisture may also be enumerated among the causes that invite the attack of infectious diseases. They are of themselves simply productive of catarrhs, rheumatisms, and the like disorders; but if an infection should be accidentally present when the body is exposed to them, then instead of these complaints, the disease peculiar to that infection will be produced62. ”

“ A curious method for arresting the spread of infectious disease is to surround the patient with a circle of some disinfectant, and during a cholera scare I saw it applied to a man on the Galata bridge who had an apoplectic stroke. ”

“ Many infections begin acutely and later change to the chronic type. Syphilis in man is a good illustration.
The differences between acute and chronic infections are partly due to the nature of the organism, partly to the number of organisms introduced and the point of their introduction and partly to the resistance of the animal infected.
An infectious disease is said to be specific when one kind of organism is responsible for its manifestations—as diphtheria due to the Corynebacterium diphtheriæ, lockjaw due to Clostridium tetani, Texas fever due to the Piroplasma bigeminum, etc. ”

“ Good hygienic surroundings may act chiefly by excluding the sources of infection rather than by enhancing resistance. Yet there is experimental as well as observational foundation for the belief in these general influences to affect the disposition to acquire or escape infectious disease. Animals which are made to fast, to over-exercise, are made anæmic, are given excessive quantities of alcohol and other poisons, or are exposed to abnormal cold by shaving of the skin, are more subject to certain infections than animals not so treated. ”

“ 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. ”

“ 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. ”

“ A disease like measles or small-pox, which can be transmitted from person to person, without immediate contact between the two, is termed infectious. In these cases the285 infection is conveyed by mucus expectorated or by dust blown about, or carried in apparel, etc., from the first patient. Such diseases may also, of course, be communicated by direct contact. If direct contact between the sick and well is indispensable for the transmission of a disease it is called contagious. There is no such hard line in nature, although some diseases can be more easily communicated than others. ”

“ In the laboratory the virulent infectious agent is brought into the animal by injection, under the skin, into the serous cavities or into the circulation, which are avenues through which in the natural disease infection rarely if ever takes place. ”

“ In fact, the spread of infectious diseases, e.g., smallpox, typhus fever, cattle plague, &c., is attributed to the presence in the atmosphere of the germs of such maladies. These germs are believed to be living beings, which develope and multiply at the expense of the tissues of the larger animals into whose systems they have found entrance. ”

“ It should be borne in mind that convalescents from many infectious diseases, such as measles, scarlet fever, smallpox, typhus, &c., are much more likely to propagate these diseases than when they are labouring under them in the acute form. ”

“ Infectious diseases, on the other hand, belong to the people, and not to the place. They are communicated from one person to another through the air, or by means of infected articles of clothing, etc., and they attack the strong and healthy, no less than the weak. Among such are smallpox, scarlet fever, measles, etc. ”

“ But if this essential condition is neglected, the power of infection is greatly increased by being concentrated in the confined and impure air; it settles upon the attendants and visitors, especially where their clothes are of wool, and is frequently communicated in this manner. A sheet wrung out in some disinfecting fluid and kept moistened with it, should be hung across the door or passage-way in all cases of infectious diseases. ”

“ Diseases which are due to unicellular pathogenic microörganisms are called infectious diseases, while if such diseases are transmitted under natural conditions from organism to organism they are spoken of as contagious diseases. ”

“ Many of the infectious diseases—and nearly three fourths of all the diseases that children have are infectious—are caught, as we have seen, from germs that are carried in the air. That is one reason why so many infectious diseases are likely to begin with running at the nose, or sneezing, or cold in the head, or sore throat. The germs, having been breathed in with the air, catch on the sides of the nostrils or at the back of the throat, and start inflammation and soreness wherever they land. This is just the way that measles, scarlet fever, chicken pox, whooping cough, and diphtheria begin. ”

“ There is not the least doubt, however, that at times we expose ourselves quite unnecessarily to infections, as when we drink water that has not been boiled or filtered, or when we take milk from uninspected dairies for a long time; or, again, when we remain too long a time in the confined air of assembly halls, etc., and breathe the air that has been exhaled by thousands of others, many of them possibly with infectious diseases of the throat and lungs. ”

“ Infectious Diseases.—It is now generally supposed that all contagious and communicable diseases are contracted by the germs which pass into the body or system. These germs are so small that millions of them may enter the body through the nose, throat, and skin. ”

“ It has already been pointed out that infectious diseases can be acquired only by the introduction of the specific germs into the human body, either through the mouth or lungs or through some skin abrasion. Further than this, it is quite as definitely known that the vitality of the germ after leaving a diseased person depends primarily upon its condition at the time of leaving the body and afterwards upon the environment which that germ finds outside of the affected person, while waiting for a chance to make its next human resting place. ”

“ The generalization that all infectious diseases are due to the introduction into the bodies of susceptible individuals of living germs capable of reproduction is based upon exact knowledge, gained chiefly during the past twenty years, as regards the specific infectious agents or germs of a considerable number of the diseases of this class. ”

“ Individuals who delve into the history of the past inform us of more and more diseases which were well known to the ancients. We are frequently amazed at the variety of diseases now known to be infectious that were very correctly described by the Hippocratic writers. The infectious diseases are with us always and live nearly always in man, the host. 109There are few exceptions. Very few of the contagious viruses can live for any long period of time outside of the human body. ”

“ Loathsome contagious diseases include those whose presence excites abhorrence in others, and which are essentially chronic, such as favus, ringworm of the scalp, parasitic fungus diseases, Madura foot, leprosy and venereal disease. Dangerous contagious diseases are such as trachoma, filariasis, hookworm infection, amœbic dysentery, and endemic hematuria. ”

“ They gain an entrance through the lungs, food canal, or skin, and, living upon the fluids and tissues, multiply with great rapidity until they permeate the entire body. Not only do they destroy the protoplasm, but they form waste products, called toxins, which act as poisons. Diseases caused by germs are known as infectious, or contagious, diseases.129 The list is a long one and includes smallpox, measles, diphtheria, scarlet fever, typhoid fever, tuberculosis, la grippe, malaria, yellow fever, and others of common occurrence. ”

“ 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. ”

“ Then we have the collections of expectorated matter and of other organic secretions, which all serve as productive foci. Every wound and sore, when antiseptic precautions are not used, becomes a most active and dangerous focus, and every patient suffering from an infective disease is probably a focus for the production of infective particles. ”

“ Investigators have studied the conditions in which these infective agents live and the manner in which they are disseminated, they have discovered methods of determining the nature of the disease in a very short time, and they have come to recognize the danger of coming in contact with germ-bearers, that is, with persons, healthy or convalescent, who have these micro-organisms in their systems without being themselves sick. ”

“ In the latter, the name of the man, date of admission, and nature of disease, is placed over the bed of each patient, which in any contagious disease gives timely warning to any one fearing infection. ”

“ 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. ”

“ Such an individual may be a greater source of infection than one with the disease, because there is no suspicion of danger. The organisms which thus grow on the surfaces have in some cases been shown to be of diminished virulence, but in others have full pathogenic power. Such passive carriers of infection have been found for a number of diseases, as cerebro-spinal meningitis, diphtheria, poliomyelitis and cholera. In all these cases the organisms are most frequently found in those individuals who have been exposed to infection as members of a family in which there have been cases of disease. ”

“ 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. ”