Milk and Tuberculosis.

Otago Witness, Issue 3061, 13 November 1912, Page 6

Milk and Tuberculosis.

Clean milk is one of the very best of foods. People of all ages from infancy to old age Jive and thrive on milk alone. It contains in delightful combination all the essentials for the nutrition of living things. That is why we love it, why animals love it, and why microbes love it. Expose pure milk to the contaminations of cowbyres, dirty milkers, road-dust, or household impurities, and in a few hours it teems with bacteria. Fortunately, most of these bacteria are not disease-produc-ing ; they may turn the milk sour or make it ill-smelling or otherwise objectionable, but they may-not do it much harm. Sometimes, however, milk becomes contaminated with virulent disease-producing germs—perhaps the bacteria of tubercle, diphtheria, or typhoid fever, or summer diarrhoea, —then serious illness may result amongst those who drink this milk. Especially is this the case with delicate children or adults whose resisting power to disease has been in any way impaired. In this short article I must perforce limit my remarks to the subject of tubercular contamination of milk.

It has been clearly proved by the researches of two Royal Commissions in Great Britain and numerous investigators elsewhere that milk can and does sometimes convey germs of tuberculosis from cattle to human beings. Exactly how frequently this happens it is hard to say, because there are many other ways of transmitting tuberculosis; but doctors frequently see cases of tuberculosis occurring amongst country children who live healthy open-air lives for the most part, and come of healthy stock, and who have not been in contact with any person suffering from consumption or other tubercular affections. Perhaps the patients have tubercular glands, or tubercular hip or knee diseases or tubercular peritonitis. Where do these patients pick up the germs of tuberculosis? Probably from the milk of tuberculous cows.

The Government of New Zealand, through its Public Health and -Agricultural Departments, is making creditable endeavours to minimise the prevalence of tuberculosis; but much remains to be done. In this connection I might mention that the self-sacrificing work of Dr Truhy King in spreading a knowledge of the fundamental laws of health amongst the community is deserving of the highest praise. Dr King is the founder and president of Uic Society for the Health of Women and Children, and through that Booiety he lias published a book, entitled “Feeding and Care of the Baby”—a book which can he very heartily commended to all who are interested in baby welfare. The food supply of cities is under fairly careful supervision, but in the country great laxity prevails, and there can bo no shadow of doubt that large numbers of tubercular cattle escape Government inspection. Here is a proof—a very conclusive proof of the risks human beings run from tubercular milk. Ever sines* dairy factories were established it has been the custom to return tlm skim-mill: to the dairy-farmers. this skim-milk being used, as food for pigs. Now. the skim-milk contains most of the bacteria, and it was soon found that the pigs fed upon it quite commonly became tuberculous—-so commonly that the Government authorities have issued a strong recommendation to all dairy factories to kill the bacteria in the skim milk before returning it to tho farmers. This recommendation will very probably soon become a compulsory regulation. The process of killing the bacteria which is recommended is called pasteurisation. and this process consists simply in heating the milk up to a temperature of 160 deg Fahrenheit for 20 minutes. When pigs are fed upon pasteurised they do not become tuberculous. Surely the'irresistible conclusions are, firstly, that human beings can similarly become tuberculous from feeding upon tubercular milk

and, secondly, that human beings uould be saved from such danger if the milk thev consumed were pasteurised. No doubt it is possible to supply milk of such purity and to siore it m such a way that even in warm weather it will remain for, say, 24 hours fre from dangerous bacterial contamination; but it is not at all easy to ensure this result. Olhei countries, however, do it, so why not New Zealand? The Lady Talbot Milk Institute in Caulfield, Victoria, is a good example of what can be done in this direction. Modem methods of milk-distribution and storage necessitate elaborate precautions both in the dairy and in the home, and however desirable such innovations maj be, it will certainly be many years before we can expect that a thoroughly reliable system will be in vogue in this country. Therefore it cannot be too widely known that milk from suspicious sources, or milk that is undoubtedly contaminated, can be rendered comparatively harmless by the simple process of heating. No doubt this heating does involve certain drawbacks—the taste of the milk is not so pleasant, the nutrient qualities are possibly a little impaired, one cannot make junket with it; but these minor drawbacks are more than counterbalanced by the security conferred against tubercular and other bacterial diseases.

These are the points I wish particularly to emphasise:

1. Tuberculosis is common in cows, and the bacteria, of this disease are passed in vast numbers with the manure, so that apart from any tubercular disease of the udders, it is obvious how easily milk may become contaminated in the byres. 2. The system at present in vogue in New Zealand for collecting and distributing milk is most unsatisfactory so far as the question of bacterial contamination is concerned. 3. It is therefore advisable by artificial means to render thg milk harmless before using it as a food, and this can be very simply done by sterilisation or pasteurisation. 4. Sterilisation is conveniently affected by placing the milk in a jug and heating in a saucepan of boiling water until the milk just reaches the boilingpoint, at which heat it is kept for about five minutes.

By pasteurisation is meant the heating of milk to a temperature of 160 deg F. (70 C.), and keeping it at that heat for 20 minutes. A thermometer and careful attention is necessary, and the microbes are not so thoroughly killed as in the

simpler scalding process; but, on the other hand, the taste is not so much altered. After the milk has been sufficiently heated it should be rapidly cooled, and the cooler it is kept the longer it will remain free from subsequent microbe infection. Needless to say, the milk should be adequately protected against flics, dust, and other gross impurities; but it is well to remember that tightly corking or sealing up milk is dangerous, because under such circumstances it sometimes happens that ptomaines develop in the milk. A. light covering, therefore, and not an airtight one is recommended. WATER AS A FACTOR IN THE SPREAD OF DISEASE. It is well known that bad water may be responsible for spreading such diseases as typhoid fever, dysentery, gastro enteritis, cholera, and hydatids, and although at present we know nothing definite about the relationship of the tubercle bacilli and water, yet it is highly probable that, directly or indirectly, a bad water supply will favour the spread of tuberculosis. In the prevention and cure of tuberculosis, as well as of all other diseases, these three essentials should be borne in mind: —(1) Pure air, (2) pure milk, (3) pure water. As a rule one may say that the water taken directly from artesian wells or rock springs is quite pure ; but the water from streams, lakes, pools, wells, tanks, and reservoirs is decidedly impure. _ In New Zealand, as in all sheep countries, there is the special danger of pollution of the water with the eggs of the hydatid tapeworm, and there are numerous ether disease-producing impurities which no doubt form a serious menace to the health of the community.

It should therefore be clearly understood that all water, no matter how pure it may look or taste, must be regarded with suspicion, unless of artesian or rock-spring origin. Good filters which are regularly cleaned and kept in order will render water from suspicious sources quite wholesome, but many of the filters in use are absolutely unreliable, and undoubtedly the safest way to render impure water wholesome is to boil it. I believe we should have very little hydatid disease in human beings and something less than the present amount of tuberculosis if greater care were taken to avoid drinking impure water. Some towns very properly go to the trouble and expense of providing the ratepayers with pure and wholesome filtered water. Unfortunately, such is not the case in Dunedin, where the water supply is practically unfiltered, very dirty, and most unwholesome.