TALKS ON HEALTH.

Putaruru Press, Volume IV, Issue 145, 12 August 1926, Page 2

TALKS ON HEALTH.

EPIDEMICS AND THEIR CONTROL. SOME NEW METHODS. Epidemic diseases, present many problems; not least among them that of their very epidemicitv, writes a medical correspondent in an English paper. Why do these diseases fluctuate? Why is there a season for diphtheria, as rigidly observed as the return of the cuckoo? Why should epidemics of influenza; on a small scale, return after a definite number of weeks, and on a grand world scale after a number of years? Why should the fatal diarrhoea and vomiting of children become epidemic whenever the atmospheric temperature has stood at a certain point for a definite length of time? Features of these kinds have always been prominent in epidemics. We now know that typhus fever and the plague, those scourges of mediaeval times, were alike spread by the bites of bloodsucking parasites, the louse and the ilea respectively. Few persons, however refined, were eyer without both th°sc creatures as constant guests. Yet the diseases were epidemic, striking down hundreds of thousands in an outbreak which spread throughout the world as far as it was then known, and then, apparently, disappearing. With all our modern knowledge we are little more able, to control epidemics than to prevent war. But wo know a little more about epidemics at least. If we take diphtheria as an example -—a disease as common to-day as ever it was, though, thanks' to the use of °p + >-toxin, much less fatal—it is now clear <,nxrt wc all harbour the bacillus at some time or other in our life. And 1 W is further clear that to become immune to the disease it is not necessary to suffer from it in. a recognisable form. It is even possible, and easy, to render a person artificially immune to it. And in that fact there certainly lies hope for the future in preventing epidemics. These facts have been established through the introduction of a test known as the Schick reaction. In order to tmderstaand this, one must know that the skin is a most reliable and convenient witness to the general sensibility of the body as a whole to a poison. Hay fever and asthma, for example, are in some cases caused by the abnormal sensibility of the patient to simple substance, such as pollen, egg, or horse-dandruff. Tlie injection of an extract of these into a healthy person’s skin has no effect, but with these patients a raised lump like a nettle sting is caused. Toxin and Anti-Toxin. The diphtheria bacillus produces in a test tube or in the body a violent poison which causes the symptoms of the disease. This is called “toxin”—a Greek word meaning an arrow. The arrow lias always stood for the symbol of plague in medicine: that is why St. Sebastian, pierced with arrows, was the mediaeval saint of plague. When toxin is injected into an animal, or is absorbed by man in the disease, a counter-agent or anti-toxin is produced. This fact is tlie basis of the anti-toxin cure; by this method normal cure takes place, and this toxin is used in the Schick test. A person who lias suffered at any time from diphtheria retains tlie antitoxin in his blood and body. Toxin, if injected in minute quantities into his skin, has no effect. But if he has never had diphtheria, then his arm swells locally; there is nothing to neutralise the anti-toxin. Such a person is in danger of contracting the disease if exposed to infection. The results of the test are of interest. It is found that at the age of two only 20 per cent, of children are immune, while just under 90 per cent, of adults are immune. Moreover, a study of the Schick reaction in a naval establishment during an epidemic of the disease showed that a. very large proportion of the inhabitants became immune without suffering from any symptoms of the disease, and that the decline of the epidemic coincided with the increase of the number of “Schicknegative” subjects.

The real importance of these observations lies in the fact that it is possible artificially to immunise those individuals who are found to be susceptible. By injecting a mixture of toxin and anti-toxin they can be protected within a very short time, and increasing use is being made of this measure. A Locarno for Bacilli. More recently a similar technique has been adopted for scarlet fever. Much dispute has been rife with regard to the cause of this disease; it appears now to be probable that the causatiye organism has been demonstrated. The test used in this case is known as the “Dick” test, from its American introduce; a protective serum is also available, as in diphtheria, for those found susceptible to infection. The striking success which has attended the practice of vaccination against smallpox indicates that a real prospect of success in the case of other epidemic disease is held out by these two new tests. Epidemic, it would seem, are disturbances of the balance between man and the parasite. The continued presence of a parasite in a community produces a people in the mass immune to infection because they have all suffered from mild attacks. Host and guest then live in amity. It is, paradoxically, tlie complete overthrow of the enemy which produces a generation without immunity, as it produces a generation without the memory of war, which alone, or chiefly, can prevent war. Alternatively, the enemy may suddenly acquire a, new weapon. One knows that, in the test-tube, variation in the characteristics of a microbe take place. Such variations arc most often without danger—a long bacillus becomes short; a ‘ 1 smooth” colony of microbes become “rough.” But it is not extravagant to suppose that some characteristic may emerge to overthrow the subtle balance between host and ’guest.