When living organisms such as germs or viruses invade the human body, the tissues of the body undergo changes which help them to resist the poisons of the invader. By this reaction the tissues become immune to the poisons. Much depends on the virulence of the infections, the total number of germs invading, the place where they enter the body, the tissues or structures where they settle and grow. If you are susceptible to the infection, it will attack you; it may even overcome you. If you are resistant, the tissues of your body may develop antibodies which will overcome the germs or viruses or their poisons.

Certain environmental conditions may increase or lower your resistance to infection. Chilling of the body, excessive fatigue, absence of some essential nutritional substance, as proteins, or mineral salts or vitamins, or the presence of another disease at the same time may modify the resistance of the body to an invader.

The chemical composition of the invading organism may be significant in the way in which the body responds to it. An invading substance is known as an "antigen." Usually the response of the body to an invading germ is specific against that germ or against that type of germ. Bacteria may contain a number of antigenic substances, against each of which the body will rebuild resistance. An example of an antibody against infections is the immune globulin. This is a protein substance found in blood, in which we now know are accumulated substances that help to resist various infections such as those of measles or poliomyelitis. In man, most of the antibodies are found in the immune globulin of the blood. The amount of antibody that develops is also governed by such factors as the amount of infectious material that gets into the body. The doctors find that they can help you build resistance by repeatedly injecting small doses of an infecting substance. We know that a child gets resisting substances from its mother in her blood at the time of birth and in the first material that comes from the breast when the child begins to nurse. This is called "colostrum." The amount of antibodies may be unfavorably affected by starvation, exposure, reduced protein intake, alcoholism, or other poisoning.

Types Of Infection

For certain diseases there are certain specific types of causative germs, such as the viruses of measles, smallpox, infantile paralysis, or the germs that cause diphtheria, typhoid, gonorrhea or meningitis. The total number of germs, viruses, rickettsia, amebas, spirochetes, or other parasites that may infect the body reaches into thousands. Many germs have been described in groups according to their appearance under the microscope such as the streptococci that grow in chains, or the staphylococci that grow in clusters. The streptococci and the staphylococci may invade any portion of the human body and set up infection.

The Common Cold

Almost anyone can tell you right off when they have a cold, and yet there is no real agreement in the medical profession as to just what a common cold is. No single germ has yet been incriminated as the causative factor nor has any group of germs or viruses been established as responsible. At present the sequence of events seems to include a first period when the lining of the nose and throat seems to respond to some foreign invading substances by reddening and congestion and a profuse flow of mucus. With this may be frequent sneezing, stuffiness, difficulty in breathing, perhaps some fever, a feeling of lassitude, and some aching of the limbs.

Colds spread rapidly from one person to another, and the resistance established by having a cold lasts a very short time. Some people have many more colds than do others; the average for the country as a whole seems to be about four colds a year. Chilling, exposure to damp, sudden changes from a dry hot air to a cold damp atmosphere, sitting in a draft, getting the feet wet, and, particularly, working or playing in crowded rooms with others who have colds seem to be important factors in the spread of respiratory diseases.

The suggestions as to how to prevent frequent colds are numerous but some doubt prevails as to whether any of them really work. You may try to keep away from contact with others who have colds, but under the crowded conditions of our civilization this is well nigh impossible. People have tried wearing face masks or gauze or paper during epidemics, but they permit contamination. Use of ultraviolet in the air has seemed to be useful but carefully controlled experiments with this technique and with spraying medicated vapors in the air have not yielded conclusive results. Mothers have tried to harden children by frequent cold baths, going without stockings, and hats and similar methods. These methods do not work, and the unnecessary hardship makes the children unhappy.

Most colds get well in from five to ten days. Complications are fortunately now controlled by the use of the sulfonamides and antibiotic drugs. Some claims hold that colds can be cured by taking an antihistaminic drug during the first twenty-four hours of invasion; most experts doubt that this is specifically helpful. The congestion in the nose is relievable by the use of decongestant preparations such as menthol, camphor, privine, amphetamine and other preparations which the doctor must prescribe. People feel more comfortable if they go to bed, take some aspirin or a small dose of an alcoholic drink. Frequently a hot bath and plenty of fluids, such as citrus drinks, secure relief. Secondary coughs are controllable with a variety of remedies. Particularly feared as a complication is secondary pneumonia. The doctor watches for signs of this in rising temperature, congestion and pain in the lungs, signs of congestion which he hears with his stethoscope, or can detect by percussion, or see certainly with the X-ray. Fortunately again, such secondary infections are now controllable with the new drugs.