HEALTH NOTES.

Otago Daily Times, Issue 19994, 11 January 1927, Page 5

HEALTH NOTES.

IMMUNITY. ACTIVE AND PASSIVE. PROTECTION AGAINST DISEASE. Contributed by the Department of Health. The physiological process by which our bodies protect themselves against microbic diseases is one of the most fascinating subjects in the whole of medicine. Its study has become possible in recent years through the discoveries of modern scientific means of research. Briefly, the cells of our bodies are able to secrete and anti-ferments, antitoxins, anti-bodies, and antidotes generally, which will: (1) Kill invading microbes, and (2) neutralise their poisonous secretions. Each kind of microbe has its own special poisons and requires its own special antibodies and anti-toxins to combat it. This power inherent in our body cells, _to thus protect themselves against or “resist” any given microbe varies in different races, families, and individuals. Even at different ages and in different sexs it varies, as well as in different states of health. But whilst this protective power belongs in varying degrees to our body cells, the cells do not exert themselves to manufacture protective substances until they are stimulated thereto by necessity. That is to say, they will not manufacture protectives till they are aware of microbes or their poisons circulating in the blood when they rouse themselves to fight and make their arsenal. Having once, however, been so roused, and having conducted a successful campaign against the invader, they appear never to completely cease their vigilance, but keep always, as it were, a number of troons and guns available for instant mobilisation against any of the same tribe who may attempt another attack. When this occurs, active immunity is obtained. MICROBES AND THEIR PRODUCTS. We now want you to distinguish between (a) live microbes and (b) their poisonous products or “toxins.” Live microbes, of course, live aud multiply and produce increasing quantities of toxin according as they flourish. But if one kills the live microbes, say in an artificial ■ cult e, there is left a definite measurable quantity of sterile toxin or poison which is no more alive than any chemical poison is alive, such as strychnine or digitalis. These are the main facts on which all vaccine and inoculation treatments are based, whether preventive or curative. ACTIVE IMMUNITY. Immunity or protection is either active or passive; one should be clear as to the difference between the two. Active immunity or protection is a protection which results from the body cells being stimulatd to manufacture their own anti-toxins and anti-bodies. It is much better and more lasting than passive immunity. As already said, it is brought about by stimulating of the body-cells to exercise their inherent capacities in this direction by means of (1) live microbes, (2) microbic poisons or “toxins” in the blood. These toxins may be made (a) by microbes living in and on the body, or (b) they may be made according to elaborate technique in a bacteriological laboratorv, PASSIVE IMMUNITY. Passive immunity, on the other hand, should be regarded only as an emergency measure to tide over a crisis, for it is temporary. It consists in introducing into the body ready-made, anti-toxins, etc., which the body-cells have taken no part in manufacturing. Anti-toxins are substances which neutralise toxins and convert them into inert and harmless compounds, just_ as alkali neutralises acid. Each toxin requires its own anti-toxin. Anti-toxins do not wake the body cells into activity nor cause them to exercise their own protective mechanism. When a person is actively ill, sav. with diphtheria, and his body cells are so overwhelmed and paralysed by toxins that they are unable to make enough anti-toxins, or make them fast enough to combat the microbes, then by injecting readv-made anti-toxins we can help his body cells and keep them alive till they can produce antibodies of their own. and an active immunity supervenes on the artificial temporary passive immunity. Or if nurses or doctors are exposed to massive infect'on, as in a severe epidemic, they may obtain passive immunity by injections of antitoxin, to protect them from such an exceptional severe attack from the enemy _ in mass formation. Passive immunity against some diseases is conferred by a mother on her baby, tthe child getting a supply of anti-toxins and anti-bodies from its mother’s blood (and possibly also from her milk), sufficient to protect it till the little immature life is well started. Though these, reduced to their simplest possible form, are the broad underlying principles o{ active and passive immunity it will be readily understood that the carrying characters of different hosts and different disease microbes produce innumerable .combinations and modifications. It has already been said that against one particular microbe the capacity of producing active immunity varies in different races, families, and individuals in the two sexes; even in the same individual at different ages and in different states of health. Then microbes of different illnesses induce different degrees of immunity lasting different lengths of time. One attack of measles, for instance, generally protects for a lifetime, however great the degree of infection to which the individual may later be exposed. But many other infections do not produce such complete or lasting immunity. Thus bacleriotherany is not applicable to all diseases, though with greater knowledge its uses are daily extending. KNOWLEDGE GAH D IN NATURE’S METHOD, Then there is the mass of infection. If the host is invaded simultaneously by ten million microbes, he will be more likely to succumb than if ho were invaded by one million. Further, there is the strength and health o! the microbes of any given disease themselves. Are they a lusty strain full-fed and vigorous from a service of easy victories, or are they enfeebled hy a succession of unsuccessful struggles? We all know how unending are the combinations which can be assumed by the 52 litle bits of cardboard in a pack of cards. But a pack of cards cannot compete_ in Dumber and variety of combinations with these resulting from the interactions of different species and different strains of microbes, in varying doses and assortments, invading varied hosts. ... From knowledge gained in studying Nature’s method of protecting the body a whole new department of medical treatment has been evolved, known as “Biologic Therapy.” This may be simply refined as medical treatment of diseases with products made by the agency of the microbes concerned. It includes all forms of treatment with vaccines, inoculations, toxins, anti-toxins, etc., and the preparation of the same. Its object is to artificially produce a real immunity, either active or passive. Artificial active immunity belongs particulary to preventive medicine, artificial passive immunity both to preventive and curative medicine. Biologic therapy and artificial immunity may, ho-vever, be dealt within another article.