FIGHT WITH GERMS,

Hokitika Guardian, 22 April 1922, Page 4

FIGHT WITH GERMS,

MAKING THE JiOllV IMMUNE. 1

SCIENTISTS’ FASCINATING WORK

(By “Excel” in the Sydney “Sun.”) It has been often observed that it a lire bo lighted in the vicinity of a scorpion the stink animal will dart its deadly tail about in all directions, and apparently into its own body, and shortly afterwards expire; and the conclusion has naturally been drawn that, terrified by the heat and flame, It had stung itself f(> death to end its misery.

However, it has been noticed on other occasions that scorpions die very quickly on exposure to moderate degrees of heat, although prevented from stinging themselves. This has caused investors to make an extract of scorpion venom and to' try the effects of injecting it through a. hypodermic needle into the animal itself, leading to the discovery that the injection, far from proving fatal, apparently did no harm whatever. THE PHENOMENA OF IMMUNITY. The same effects ensued when smoko venom was injected into snakes. Experiments have shown also that certain animals, such as hens or alligators, do not become ill when inoculated with the germs of lock-jaw, (or tentanus). These’animals are said to be immune to these poisons. These investigations into the phenomena of immunity, all intensely interesting, have occupied the attention of many .scientists of recent years. The cases above mentioned are instances of natural immunity; but it is phi in that it would he of immense mcdi.al importance if people could artificially be made nonsusceptible to diseases against which mankind does not possess this natural immunity; and this 'lias been shown to be possible in the case of many illnesses caused by riiixcrobes. It is well-known that nearly all persons who have survived an

attack of smallpox, typhoid, or scarlet fever, arc extremely unlikely to lake the same disease again. They have acquired artificial immunity. But although the immunity thus gained is of a very high order this method of immunisation is very inconvenient and dangerous, and much milder and safer ways have been discovered. SMALLPOX.

-Many years ago Jen tier noticed that during an epidemic of small pox dairy hands who had fairly recently contracted cow pax while milking infected cows, never sulfored from the more serious complaint. And lie came to the conclusion that cow-pox was a mild form cf smallpox. Hence, he argued, why not produce cow-pox (or vaccinia) in a!! persons exposed to small-pox, end thus protect them against tlm shourge? .Alter the usual opposition !iis idri. prevailed and the wonderful success of his method is well-known.

This was an artificial immunity produced by the inoculation of a mild form of smallpox germ, or an “attentiiated virus.” a; the scientists call it. In later years, after Pasteur’s marvellous d : stovorics of germs and their influence in the iniisation of disease, oxp'cM iincnts w ere made by him to see if other microbes could - not be reduced to an attenuated form and, used to protect animals and men against the illnesses caused by them. PASTEUR'S EXPERIMENTS.

He found that the bacilli of anthrax which was ravaging the (locks of France, were much weakened by being gj 'nv. n a.rtilii iallv at a rather higher temperature than they were accustomed to; and that sheep injected with this culture were hardly affected at all, and. moreover, were also able to resist the injection of slightly more virulent germs grown at a slightly lower temperature; and after a series of injections of bacilli grown at temperatures more and more approaching to the normal the animals bore with-

cut serious symptoms injections of ordinary viruic.nl 1;..k ilii in doses that would ordinarily have proved fatal. |t w:is also noticed that the dead bodies of ccrt"iin germs contained ]>oisons or toxins that, injected in large quaniities, caused severe illness or even death; Lu if used in small; but gradually increasing doses at short intervals, had the effect of making the animal not only immune to very large doses of the dead germs, but also nonsnseeplible to the particular disease

<a”scd by the injection of the living g rms themselves. The immunity of

sna'-e c!:erme ,, s is due to their inoeulutin r themselves with small doses of

snake venom. PASSIVE IMMUNITY. f lhis process of making an animal immune to a particular disease by inoculating it with the germs, (or their toxins) of; that disease is called “active” immunisation. But it was also discovered that tin* blood of animals thus treated bad a. curative effect v» 5 1 •11 injected into other animals actually suffering from that disease. This was a. most valuable observation, because it is plasn that it takes time to develop an active immunity, while the lull benefit of the second method which is termed “passive” immunisation, can he given the sufferer at once. This

passive immunity is not so lasting as the active, hut is extremely useful when tune is of the utmost importance, as in an attack of diphtheria. lit the case of plague, both protective vaccines and curative .sera, have been

| m a nu fa cured. ' Tt should bo explained here that the j injections of the dead or attenuated Rerins or their toxins are called vae- , vines, while the substances antagonisi fie to these that are found in tho blood of animals into which the former , have been introduced are antitoxins; j as the antitoxin ornnofc be se- : paraded from the ldood serum in whirl* it is dissolved, tho material inje-tod is called “antitoxin” or “antitoxin soj mm,” or simply “serum.” There is much popular confusion on this point, the terms “vaccines” and “antioxins” being wrongly used, as if they were interobangea b !e. j TUB MAiVPFaCTPRE OF } VAOOIX.es . I ae method of manufacturing vaccines is interesting. Typhoid vaccine will serve as n typical instance. ft' was used most successfully to protect the troops in the Into war against that disease, which, in the Boer war, was much more deadly than the enemy’s bullet. Typhoid haeilli are grown on agar-agar in pure culture—without admixture of other germs—-

and are then washed off into a dilute solution of Balt and water. They are shaken up in this with-beads, to break up any clumps of bacilli, and are'then killed by heat, mixed with a tiny quantity of antiseptic, and sealed in a Sterile vessel for storage. Then the number of germs in a definite amount of the fluid must be determined, so that a known dose may he administered. (A common dose of this vaccine is 1,000,000,000 microbes). Once the germ content is known we can prepare other similar vaccines by making a strong suspension and diluting it. To make antitoxin, on the other hand, either the germs themselves or their toxins arc injected into another animal, generally a horse. Let us take diphtheria antitoxin as an example, since the same principles apply to its manufacture as to that of tetanus antitoxin, snake-bite antivenine and all other antitoxins. These germs, grown in Ihoi.i, produce toxins that pass out of their bodies into the surrounding fluid, and can he filtered off, leaving the bacilli behind. A tiny amount of this toxin is injected into a healthy horse and at intervals of a few days increasing doses are administered, until after a few weeks the horse can take relativcly-trcmeudous doses without ill-elfeet.

ANTI-TOXIN FROM THE HORSE. A vein in the animal’s neck is then tapped and a quantity of blood drawn off. This is centrifuged to get rid of the corpuscles, and the. straw-coloured fluid removed from them is the serum containing the anti-toxin. 01 course, this process is somewhat exhausting to the horse, and he has usually to be given long holidays between tapping But recently the Commonwealth Laboratory experts at Melbourne devised a method of returning the corpuscles to the animal, thus greatly diminishing its weakness and increasing its capacity as a faclorv of auti-tOxin.

This serum is tested to prove that it contains no harmful germs, and also to determine its anti-toxic strength. This latter process is carried out by finding the least amount of toxin that, it injected into a guinea-pig of 250 grammes weight, will cause death in four days is taken as the unit of anti-toxin.

Many people have charged the imti’toxin with, earning the paralysis of lip. eye or throat, cr oL.er disabilities that are occasionally the legacy of an attack of diphtheria. The probable truth is that the attack was a very virulent one, and that, while the antitoxin saved the patient’s life, it could not prevent these sequelae. Hence antitoxic treatment should never he declined on this ground.