VACCINES AND SERUMS

Dunstan Times, Issue 3516, 6 April 1931, Page 3

VACCINES AND SERUMS

TRIUMPHS OF SCIENCE Few of the triumphs of science applied to medicine are so wonderful as the ability to light disease by paying back germs in their own coin. People get “ injections for so and so,” or assert that they “ have had measles before and cannot get them again,” but the average person has rather vague ideas as to the real significance of such statements. Every animal body makes an cllort to fight any material of protein nature which is foreign to it and which gains entrance to the blood stream. By protein is meant the very complex substances containing nitrogen winch form the bulk of all living tissues. The body is stimulated by the foreign protein to produce opposing substances known as anti-bodies, which attack it and render it harmless and further dissolve it to be expelled from the body normally by the •kidneys. Since the bodies of disease germs can be ugc n :i as mainly living foreign protein, it is evident that a potent weapon lias been bestowed upon the animal body for resisting invasion by these tiny intruders. This force is also applicable to the non-living poisonous proteins such as the snake venoms and the vegetable poisons such as a brin and ricin.

The actual living germ may be regarded as harmless, per se, but the damage resulting in disease is due to the products of the germs of poisonous character. The resisting substance produced by the body may attack the living germ or its products. Modern bacteriological technique can provide us with supplies of artificially-grown germs, and research has been so intense that to-day the number of diseases which will not yield to some vaccine or serum treatment is small. A better name for the harmful products of disease germs is “ toxins,” and the things produced by the anitnal body to fight and neutralise them “ anti-toxins.” The most powerful toxins are' those which are given out by the germs while living normally, and are known as “ exo-toxins.” Fortunately the exotoxin producers are comparatively few in number, but the symptoms produced are very acute, as seen in diphtheria and tetanus (lockjaw). The liquid called “ tuberculin,” which is used for diagnosing tuberculosis, may be regarded as an exo-toxin produced by the tubercle bacillus while growing abnormally. The other kind of toxins constitutes the “ endo-toxins,” which are liberated only on the death and disorganisation of the germ. Chronic and less acute symptoms are typical of this type, such as are experienced by the carbuncle sufferer.

The following is the procedure adopted to control the ravages of the invading germs and their toxins when the body is fighting a losing fight because it fails to supply anti-bodies at a fast enough rate. If we inject a small quantity of the living germs there will he insufficient of them to gain the upper hand, but thev will immediately stimulate a large over-production of anti-body for future use. The use of this method is attended with a certain amount of danger, and is rather limited. This, of course, happens naturally when we have actually had the disease, and the immunity thus gained may last lor years. A similar effect may be obtained by first killing the germs we inject, as in the case or many vaccines for boils and abscesses, or by weakening them by culturing them at abnormally high temperatures or with antiseptics. A notable example is seen in anthrax vaccination. In the case of smallpox a quantity of cowpox culture is injected. These two organisms arc exceedingly alike, and although the anti-body which cowpox germs gives rise to will effectively check smallpox, yet the relative seriousness of the two diseases is not to be compared. It is also possible to inject small quantities of exo-toxin and so stimulate the production of anti-toxin. The outstanding examples of Ibis method arc diphtheria and tetanus anti-toxins. All the means so far quoted are classed as “ active ” immunisation, because the conflict occurs in the actual body of the patient. When we have given him so much toxin that his body is simply chock full of anti-toxin we may simply draw off a little oi his blood and separate the serum from it. This serum may he injected as required into a patient, and we can snap our fingers at the disease. This is now the position in regard to tetanus and diphtheria and many others. Lately tiger snake venom has been added to the list of serum anti-toxin conquests. It is disease that is helping to keep man a little lower than the angels. But it is achievements such as these that raise him just a little higher than the rest of his fel-low-animals.