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Te Awamutu Courier, Volume 65, Issue 5525, 16 September 1942, Page 5

SCIENCE’S NEW DISCOVERY DEVELOPING IMMUNITY FROM A PEST ,

'(By

L. R. Richardson,

M.Sc|, Ph.D.)

In enlightened times it was tljoughi that some people were inypljbreeders of .hpe, .nothwith:standing their personal hygiene, and were consequently always infested with the parasites. Science has • revealed that in certain circumstances the presence of lice can be ascribed to a diet deficiency, This further, evidence of the association between skin chemistry and disease js discussed by Dr. Richardson in this new release from the New Zealand Association of Scientific Workers.

The last world war, like many before it, has been called a “lousy” war. Anecdote, pencil, and camera have preserved ample testimony in support of the literal truth of this particular statement of the old soldier, and of the soldiers of earlier wars. Trench warfare in France gave the louse the opportunity to become a major military .problem. Extremely heavy infestations with lice was another inconvenience added to the many already suffered by the soldier in the front-line. Scientific aid was called in, and devised techniques which were energetically applied to free the soldier and his clothing from this pest. Owing to the practical impossibility of cleaning up the trenches, it was not possible to put a stop to this particular epidemic. Men were reinfestr ed as soon as they returned to the trenches.

Scientists have not forgotten this problem of our previous wars, particulaily since lice are sometimes the agents for the transmission of the highly dangerous typhus fever. This disease has frequently flared up in peace as well as war. Even in the last war, hundreds of thousands of people perished from typhus; but fortunately this louse-borne disease did not appear on the Western Front. Since the last war, the study of animal parisites has made remarkable progress. One of the most outstanding discoveries is the fact that animals and man can develop or possess undei| certain conditions a relative immunity to animal parasites such as tape-worms, round,worms, and even — lice. This immunity is somewhat like the immunity to many of the bacterL al parasites, which cause disease; but it is seldom complete. The immune •animal will-have only one or two anil mal parasites; the non-immune, a very heavy infestation.

The reason for this immunity are not yet by any means clearly, understood; but nevertheless the existence of quite extensive immunity has beer demonstrated beyond question foi many kinds of animal -parasites, ■ •

~ In : some cases the immunity ’is quired with age. This is the reaspn children, but more rarely adults? are infested heavily with pinworms, Spnjetimes the immunity is associated ■■with climatic factors- Recent work has shbwn. that - in the case of lice, the im-i niunity is' associated jyith the nature .of‘the healthy, normal skin. In the course of nutritional experiments on animals, it had been noted by some workers that healthy animals had less lice' than those in poor condition. The recent study Ky Kartman in the Unit-, ed States has produced- . remarkable! confirmation of this observation/ -Kartman found that rats fed on a ,djet lacking vitamin A developed an average infestation of 1451 lice per rat; others, fed on the same diet and then given restorative feeding, had •only 28 lice per rat. Normal healthy rats under the same conditions were infested with only 12 lice on an average.

Other work has shown that the vitamin is not - ., itself responsible for the immunity; but in the experiment, lack; df the vitamin disturbs the skin-; forming processes and so destroys the immunity with which is a property of 1 .the normal skin,. In the case of vita-' min A, this is concerned, among other l things, with the process of keratinizati’on by which the living cells beneath the skin are transformed into the tough protective layer which forms the surface of the skin. The louse must bite through this to reach the blood on which it feeds, and so the immunity to lice depends on the nature of the skin. Kartman’s experiment, and the work of other scientists, has proven that we must look to the problem of skin-chemistry before we can understand completely the natural immunity of lice. The striking figures of Kartman’s experiment help us to understand the severe infestations with lice such as were seen in the last war, and show how dietary deficiencies may be responsible in part for the epidemics of liceborne disease in war-ridden countries where food-shortage means monotony in diet. Such monotony is the commonest associate of deficiency in diet.

There is no doubt that the last war was a “lousy” war. Scientists then were not able to completely cope with this problem; but they did their best. It will not be their fault if this war is as “lousy” as the last. They have a better understanding of the problems involved. They are not yet content. Scientists are still trying to solve the final problems of skin-chem-istry which will bring man immunity at all times from these pests which have so often been the cause of inconvenience and even death in the past history of man.