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Infection and Disinfection: Hence

These they regard as their natural home. Hence they can thrive and multiply only under very similar conditions of warmth, moisture, absence of direct sunlight and presence of a supply of food suitable to their necessities. They are so exceedingly small as to be totally invisible to the naked eye, and are without color, taste or odor. Hence the presence in an ordinary well of bacteria sufficient to kill all the inhabitants of a great city could not be detected without the use of a microscope except through their fatal consequences.

It was formerly supposed that the introduction into the human body of one or more germs of any contagious ailment was certain to result in the contraction of a typical case of the disease. The use of the microscope has proved that this is by no means the case. The germs of pneumonia, diphtheria, tuberculosis and others are often found in the throat and lungs of perfectly healthy persons.

The germs of various diseases may be swallowed without injurious results.

The likelihood of contagion depends in part upon the number of the bacteria that may gain lodgment in the system, in part upon their vitality, and in part upon the state of health of the afflicted person. Most germs tend to breed and multiply in colonies. They do not live long outside of the human body, or other living host, except under favorable conditions, and the body when in perfect health has considerable power to resist their invasion. The vitality of different species, or of the same species under different conditions, varies considerably. The germ which causes consumption, the tubercle bacillus, is among the most resistant. The germs expectorated by the consumptive may be found in a state of full vitality, in the dry sputum of the patient, floating in the air as dust. With this exception, however, it is believed that exposure to dry heat and especially to direct sunlight kills most disease germs or greatly weakens them. The effect of cold is merely to suspend their activities. Freezing for an indefinite time does not injure most germs. But all are destroyed by exposure to heat at or near the temperature of boiling water, or by contact with various substances known as germicides or disinfectants.

The most virulent bacteria will die of themselves within a comparatively short time after they are thrown off from the body of a diseased person, unless by chance they find congenial INFECTION AND DISINFECTION lodgment in warm, dark places such as open vaults or drains or in another human body.

The germs of diphtheria, typhoid and some other diseases will multiply quite rapidly in fresh milk, although they are commonly destroyed by the lactic acid which forms in milk in the process of souring. They will, however, live for some time in cheese and butter. Hence contamination of the milk supply is one of the most frequent sources of infection.

Bacteria do not appear to multiply in ordinary drinking water. On the contrary, it is believed that the germs of typhoid will die out of wells and cisterns in about a week or ten days if there is no further contamination in that interval. The contamination of water supplies is, however, among the most frequent causes of fatal epidemics of typhoid and some other diseases. The pollution is usually continuous and often increases in amount and virulence until attention is drawn to it by an outbreak of disease.

The discharges of patients suffering from typhoid and similar diseases contain myriads of the living bacteria. When these find their way by seepage, or surface drainage from open vaults to streams, springs, wells and cisterns, or through the outflows of sewage being in too close proximity to the intake of water supplies, the number of germs swallowed is almost sure to bring on the disease in its most virulent form.

Other common sources of infection are vegetables, contaminated by polluted soil, pet cats and other animals, and, in short, anything which may serve as a vehicle to transport the living germs in a fairly direct route from one human body to another.

While a person in perfect health may come in contact with the germs of disease with impunity, especially if they are few in number, and if their vitality has been impaired by exposure to drying heat or otherwise, yet every precaution that science can suggest should be taken to avoid such Or contagion. Persons in the best of health may become susceptible to the attacks of bacteria by the lowering of tone due to over-fatigue, to a sudden cold, or similar causes. the disease may be taken in such mild form that its true character may not be recognized. Such an attack may cause the patient little inconvenience, but may result, in the absence of proper precautions, in the spread of the disease to others in its most virulent form. Indeed, such cases, and those called healthy "carriers" are known to be among the most common agencies in the spread of epidemics.

Healthy "carriers" of disease, in medical parlance, are patients who have recovered and become immune to the bacteria of a germ disease, but who are still breeding such germs in large numbers in their bodies. Ordinarily, the germs of disease disappear at or near the time of the patient's recovery, but in exceptional cases persons have been known to be "carriers" for many months or even years. Such persons are especially dangerous, because the liability of infection from them is not usually suspected. Yet, in the absence of absolute cleanliness and proper precautionary measures, they may be the means of infecting others, or contaminating sources of water supply. A typical case is that known to medical men as "Typhoid Mary." This woman is known to have infected about twenty-four persons in six different families where she was employed as a cook. Another recorded instance is that of a dairyman, a carrier of typhoid, who caused no fewer than three epidemics in a western city through the contamination of the water supply which was used by him for cleansing milk cans and other receptacles.

Prevention of Contact Infection.- There are two distinct lines of action which must be adopted to insure against infection. The first consists in preventing all possibility of the contamination of the soil, pollution of water supply, or transmission of the germs of disease by flies and other insects. This may be done by abolishing all open vaults and drains and by the sanitary disposition of all slops, garbage, dead animals and other household or farm refuse.

Statistics show that such steps, if properly taken, will reduce the likelihood of infection about one-half. Thus, in the city of Springfield, Ill., the death rate from typhoid continued to increase even after the introduction of an efficient water supply and sanitary sewerage. An investigation by the Board of Health disclosed that only about one-third of the property owners were availing themselves of these improvements. Twothirds of the families were still dependent upon cess-pools and open vaults. When these were abolished by city ordinance, the death rate from typhoid was reduced about onehalf. A similar result was observed in the city of Providence after all cess-pools and open vaults were abolished by municipal ordinance.

The other line of defense consists in the observance of absolute sanitary cleanliness and the proper use of disinfectants, especially in times of epidemic or when there are cases of contagious illness in the family or neighborhood. It has been proved beyond question that, if proper precautions are taken to avoid infection from milk or water supplies, insects and similar causes, and if sanitary. precautions are observed, a patient with any contagious disease may be nursed in his own home without infecting other members of the family. In certain high-class French hospitals, patients suffering from all sorts of contagious diseases, such as diphtheria, smallpox, typhoid fever, scarlet fever and others, are treated in the same open wards and waited upon by the same physicians, nurses and attendants. The only separation of one patient from another is by means of low screens or partitions made of cotton cloth. Even these are sometimes omitted and the space allotted to each patient is defined merely by a line of tape or by marks chalked or painted upon the floor. The object of these is simply to call the nurse's attention to the necessity of observing sanitary precautions before crossing the territory of one patient into that of another.

No object which has touched the person of a patient or been contaminated by any of his discharges is permitted to touch the person of any other patient. The nurse and the attending physicians wash their hands in a disinfectant solution each time they touch or handle the patient or anything which has come into contact with him, before approaching the bedside of another sufferer. Under this plan, which is known as the French cubicle system, instances in which a patient suffering from one contagious disease has become infected with another are extremely rare, while all are being treated in the same room and are breathing the same air.

DISINFECTION The purpose of disinfection is to kill the germs of contagious diseases after they leave the body of the patient and before they find another victim. This may be done by means of heat by boiling, baking or burning the infected material, or by means of various chemical poisons known as disinfectants or germicides. These are usually applied in liquid or gaseous form. Germs can be killed by heat or disinfectants only under the following conditions: The heat must be sufficiently intense or the disinfectant sufficiently strong; the germs must be thoroughly exposed to the heat or disinfectant; and for a sufficient length of time. Disinfection by heat may be by fire, boiling water or live steam. No special apparatus is needed if fire or boiling water is used. The infected articles are simply burned or boiled.

Articles to be disinfected by boiling should be weighted, if necessary, and INFECTION AND DISINFECTION kept under the water while actually boiling for not less than half an hour. The addition of common washing soda to the water, at the rate of one moderate tablespoonful to each gallon of water, increases its efficiency.

Steam disinfection, on a small scale, may be accomplished by means of an ordinary wash boiler containing a wooden rack resting upon bricks, or otherwise suspended above the level of the boiling water. Pack the articles to be disinfected closely upon this rack, put the cover on tight and boil briskly at least an hour. Be sure to use enough water so that the boiler will not go dry.

Many kinds of clothing and other objects which would be injured by boiling can be safely disinfected in this manner.

All stains should be removed before disinfection by steam or boiling water, as heat tends to fix them.

Disinfection in General. - Most of the so-called disinfection practiced in families is inefficient and useless. The burning of coffee, tar, or other substances in the sick room or elsewhere in the presence of the patient or others, operates at most only as a deodorizer. Such fumes do not destroy the germs of disease. Open vessels containing chloride of lime, carbolic acid or other disagreeablesmelling substances have no value for disinfecting purposes, unless the infected material is actually immersed in them. If bad odors exist, remove the source and admit an abundance of fresh air. Never use disinfectants not vouched for by reliable authorities. Disinfectants, germ killers, and the like, sold like patent medicines are most often expensive and worthless. They should never be relied upon. The following solutions are for use during illness and for general family use as directed.

Allow nothing to go from the sick room in case of communicable diseases without having been disinfected with one of these solutions. It should be an unceasing duty of the nurse or other attendants to see that disinfection as here indicated is carried out to the minutest particular.

STANDARD DISINFECTANT SOLU- TIONS Substances recommended as reliable disinfectants for general external use in contagious diseases are (1) chloride of lime; (2) quick lime; milk of lime; (3) bichloride of mercury (corrosive sublimate), either with or without the addition of muriate of ammonia, or permanganate of potash; (4) carbolic acid, and (5) solution of formaldehyde (formalin).

Such substances as Lysol, Kreolin, Tri-Kresol and other much advertised patented preparations are no better than the above and are too expensive for general external use in sufficient quantities. The following standard disinfectant solutions are those endorsed and recommended by public health authorities throughout the United States. They are the cheapest, best known and most reliable disinfectants. No others need be employed for general external use, Most of these solutions are highly poisonous. None are suitable for washing out the mouth, gargling the throat, or other internal use.