Rural Hygiene

by Henry N. Ogden

Between these two extremes—the use of milk for the very young and for the aged and infirm—milk plays an important part as food. The consumption of milk in New York State, according to statistics, amounts to about a pint a day for each person for that part of the country. As an article of food, milk has the advantage already referred to, namely, that besides its nutritive power it has a curative effect greatly augmented by fermentation, the modification so vigorously advocated by Metchnikoff. Another advantage which milk possesses as an article of food is that, by sterilization and storage in closed vessels, it may be kept for days and even months in good condition. At the time of the Paris Exposition, milk was sent from America and exhibited alongside of French milk with no preservatives except heat used for removing the bacteria in the milk and then cold storage for keeping others out, and two weeks after the original bottling the milk was in good condition. To meet the need of ailing babies, advantage was taken of this valuable property of milk, by which it could be shipped from dairies near New York to the Isthmus of Panama, and used continually with good results although more than a week old.

Bacteria in milk.

The great disadvantage which milk sustains as an article of food is that the same composition that makes it so useful as a diet for man, also renders it a most admirable culture medium for the rapid development of all kinds of bacteria. Some of these bacteria are, without doubt, benign in their effect upon man; as, for example, the particular species used to produce koumiss and other varieties of fermented milk now recommended by physicians. But there are many other kinds of bacteria that find life in milk congenial, whose effect upon the human system is not salutary, and, if milk infected with those varieties is used for feeding infants, the result is quite likely to be a disturbance of their digestive system, producing diarrhea and cholera infantum and possibly death.

It was at one time common to add to milk certain antiseptics for the purpose of preventing the growth of bacteria, and, except that the preservatives acted quite as injuriously upon man as upon the bacteria, the results, so far as merely keeping the milk went, were all that could be desired. The chemicals added were borax, boracic acid, salicilic acid, sodium carbonate, and other similar disinfectants. Gradually, however, it has come to be known that, inasmuch as the milk when first drawn from the cow's udder is sterile, that is, contains no bacteria, and since it is quite possible to prevent the introduction of bacteria into milk during the processes of milking, straining, and bottling, there is no need of the addition of preservatives, provided particular care is exercised in handling the milk.

Effects of bacteria.

Since this care involves the expenditure of both additional time and money, questions at once arise whether such expenditure is necessary, whether the introduction of a few bacteria into the milk is objectionable, and what the results are upon the persons drinking milk containing bacteria. For our present purpose, the kinds of bacteria which find their way into milk may be divided into two classes, namely, those that are normally in milk and which tend to produce souring, and those which accidentally enter and are able to produce disease in persons drinking the milk. The first kind probably enter the milk from the air or from the surface of the milk-pail, and in the milk increase in numbers very rapidly and have the same effect in the milk and on persons drinking the milk as any large amount of organic matter.

The second kind of bacteria are known as pathogenic; that is, are the direct cause of disease when taken into the human system. Under ordinary circumstances, this latter class will not be found in milk, since these kinds of bacteria must come from some infected person, and if no such person is in contact with the milk at any stage, then it is impossible for the milk to become so polluted. However, those interested in preventing the spread of disease through polluted milk argue that if the conditions in a stable and dairy are so unclean that large numbers of the normal milk bacteria can enter the milk and increase in numbers there, then conditions would be favorable for the introduction of pathogenic bacteria whenever the milker or bottle-washer or the strainer or any of the helpers became sick.

To show the difference in the effect of a clean stable and dairy as compared with an ordinary one, it is only necessary to say that in investigating the quality of the milk supply of a certain city recently, the writer found one stable where the milk analyses showed from half a million to a million bacteria per c.c.,[2]—that is, per half-teaspoonful,—and this was occurring in the dairy regularly from month to month as the analyses were made. Another stable in the same city showed just as regularly a bacterial count in the milk of from 1000 to 5000 per c.c., the difference being due solely to the way in which the stables and dairies were kept,—in the one case with no regard to cleanliness and in the other with the very best attention paid thereto. Certainly, if dirt is so much in evidence that a million bacteria can enter the milk in every c.c., no particular pains can be taken in such a stable to keep out disease germs; while in the clean stable, where so few germs enter, disease germs could hardly find any opportunity for lodgment.

The following example may be given to indicate the effect of impure milk upon a community. The vital statistics of the city of Rochester, including the deaths of children under five years, show that from 1889 to 1896, during the summer, infants died at the rate of 109 per 100,000 population. The health officer of the city undertook to improve the quality of the milk, and from 1896 to 1905, statistics show that the number of children dying, under five years, was only at the rate of 54 per 100,000,—a manifest saving due, without doubt, to the improvement in the quality of the milk. By repeated examinations of the dairies, by rigid enforcement of certain rules governing the distribution of milk, and by detailed lessons to mothers in the tenement-house districts on the care of milk, the quality of the milk was so improved as to make the reduction in the death-rate already pointed out.

The Honorable Nathan Strauss, of New York City, has taken up the same idea, and, by supplying the poor with milk properly heated so as to destroy the bacteria which may have been introduced by careless handling, has also saved hundreds of thousands of children from premature death.