27. The interior of figure 26.

28. A mere pretense of a milk house.

29. A dirty, untidy milk house.

30. A very neat, inexpensive, small bottling room.

31. A milk room with poorly located tank.

32. Children washing milk bottles.

33. Entrance to dairy in basement.

34. Dairy room in cellar.

35. A sterilizing oven.

36. Bottling room in a high-class city dairy.

37. A modern high-class pasteurizing plant.

ARTICLE NO. 16.-SANITARY WATER SUPPLIES FOR DAIRY FARMS.

38. Geological formation of artesian wells.

39. Cesspool not polluting well lower down.

40. Cesspool polluting well opening above it. 41. Bad pump surroundings.

42. Good pump surroundings.

43. Good well situation in building.

44. Good natural spring situation.

45. Bad natural spring situation.

ARTICLE NO. 17.-METHODS AND RESULTS OF EXAMINATION OF WATER SUPPLIES OF DAIRIES SUPPLYING THE DISTRICT OF COLUMBIA.

46. Field kit.

47. Shipping box.

48. Alcohol lamp.

ARTICLE No. 21.-INFANT FEEDING.

49. Chart showing deaths from gastro-enteritis in infants, Paris, 1897.

ARTICIE NO 22.-THE MUNICIPAL REGULATION OF MILK SUPPLY OF THE DISTRICT OF COLUMBIA.

50. Chart showing the death rate in the District of Columbia from diarrhea and enteritis among children under 2 years of age, 1880-1906.

Milk and its Relation to the Public Health.

1. INTRODUCTION.

By WALTER WYMAN,

Surgeon-General, Public Health and Marine-Hospital Service.

During the last few years increasing attention has been given to milk in its relation to the public health. This is especially true in the United States, where the more progressive health authorities of the larger cities and many of the States have been instrumental in markedly improving their milk supplies.

The question of sanitary milk is to the American people especially pertinent. Milk is perhaps used to a greater extent in this than in any other country. It holds a peculiar place in the nation's dietary because of its varied applicability. Containing as it does all the essentials of a perfect ration, proteids, carbohydrates, fats, inorganic salts and water, it is capable of almost universal use. Because of this and, in addition, its facility of ingestion and comparative ease of digestion, it constitutes an important food for the sick and convalescent.

Of even greater importance is the use of cow's milk as a substitute for mother's milk in infant feeding. It will be perceived that those most dependent upon this food-the sick and convalescent, infants and children-constitute that part of the community suffering the greatest injury from the use of a food impaired in its nutritive content. This is due to the fact that they are least able to resist the harmful effects of foods contaminated by toxins or pathogenic microorganisms. While improved conditions of living have contributed to a steady decrease of the general mortality in civilized countries, this unfortunately does not apply to the infant population under one year of age. It is recognized that gastro-intestinal disease is the largest single factor determining infant mortality, a condition in great measure due to improper methods of feeding. This enormous loss of potential wealth is of grave concern to the State and worthy of most careful consideration. It is especially for these reasons that the question of sanitary milk and its relation to the public health challenges our best endeavors.

The investigation into the origin and prevalence of typhoid fever in the District of Columbia during 1906 by a board of officers of the Public Health and Marine Hospital Service brought out many facts emphasizing the possible danger of milk as a carrier of this disease. Through the interest of Dr. G. Lloyd Magruder, who had been impressed with these facts, the President, and the Secretary of the Treasury directed that the United States Public Health and Marine-Hospital Service invite the cooperation of the Bureaus of Animal Industry and Chemistry of the Department of Agriculture in an investigation of the milk industry of the District of Columbia from the farm to the consumer in its relation to the public health.

In order to properly study the subject as it exists in the District of Columbia, it was deemed necessary to treat the matter from a broad point of view; that, to study the local aspect of a world-wide problem, the findings and experiences of others must necessarily be considered. In many respects the Federal Government has peculiar advantages for the study of these problems which, strictly speaking, are not confined to any one locality, but are national in scope. It is , therefore incumbent on the National Government to assume its responsibilities and attempt the solution of scientific questions of this character influencing the lives and health of its citizens. Because of the relation the Public Health and Marine-Hospital Service bears to the conservation of the public health, it was determined to make this investigation of such a character that, in addition to being of local value, it would also be of assistance to health officers at large, and especially to those not as yet provided with the necessary laboratory facilities and corps of workers such as can be afforded only by the richer and more densely populated centers.

It has been the object to include in this volume all available data showing the influence of milk as a carrier of infection, its chemical composition, the contaminations found therein, their influence upon it as an article of food, and the measures necessary in its production and handling to prevent such contamination.

Milk in the udder of a healthy cow is rarely sterile, but with proper methods can occasionally be removed in small quantities free from micro-organisms. In this condition it may theoretically be considered normal milk, and as such has been kept for over two years. But this is not the milk of commerce. In the healthy cow, milk may contain organisms while still in the udder, or receive its initial contamination with the omnipresent microphyte in its passage through the ducts of the animal's teats. This may be considered its first point of contact with the outer world, for these organisms in the healthy animal have gained access to the ducts from without. At every other

point of contact on its twelve to forty-eight hour journey to the consumer it receives additional bacteria.

Milk holds a peculiar position among foodstuffs in that it is an excellent medium for the growth of many micro-organisms, both the ordinary saprophytic varieties and those pathogenic to man. These factors often produce in market milk an enormous bacterial content. Zakharbekoff found that in St. Petersburg examination of samples of milk as delivered to the houses showed the presence of from 10,200,000 to 82,300,000 bacteria per cubic centimeter. Samples of market milk at Giessen have shown over 169,000,000 per cubic centimeter, New York City milk as high as 35,200,000, London milk 31,888,000. In Washington, examinations made at the Hygienic Laboratory of the Public Health and Marine Hospital Service during the summer of 1906 showed a maximum of 307,800,000 and an average bacterial content of 22,134,289. Were milk transparent, this luxuriant growth would be evident to the naked eye, but because of its opacity such contamination occurs unnoticed. Fortunately, most of these organisms are saprophytes, but there are good reasons to believe that they may elaborate toxins, rendering milk dangerous as a food.

It is evident, from a broad view of the subject, that a pure and wholesome milk supply is possible, and this volume contains all the necessary information to attain that end, as well as the existing standards of purity to which it should conform.

The three cardinal requirements, cleanliness, cold, and speedy transportation from the cow to the consumer must be observed, and the cow herself must be free from disease. For their observance, intelligence and care on the part of the dairyman and milk dealer are absolutely essential.

The bearing of all these points upon the wholesomeness of milk, its treatment when contaminated, and its use as an article of food, especially for infants, has been treated in detail by the various collaborators. To ascertain how serious an indictment might be returned against milk as a carrier of disease, a compilation of epidemics produced by this means has been made by Doctor Trask. Reports of 500 epidemics have been abstracted in tabular form and appear in the text. These are only the few that have been reported and are accessible in the literature; how small a fraction of all cases this must be can only be surmised.

As a result of large experience, Doctor Lumsden describes how the milk supply of cities becomes contaminated with typhoid bacilli, and the best epidemiological methods of determining the influence of milk as a factor in the propagation of typhoid fever.

With a view to determining the presence or absence of tubercle. bacilli in the market milk of Washington, Doctor Anderson examined

272 samples from 104 dairies. He found that 6.72 per cent of the samples contained tubercle bacilli virulent for guinea pigs, and that 11 per cent of the dairies whose milk was examined supplied milk containing these micro-organisms in sufficient number and virulence to render guinea pigs tuberculous. The milk purchased by one charitable institution for the use of children caused tuberculosis in the animals upon which it was tested.

Evidence of this character again emphasizes the necessity of applying the tuberculin test among dairy herds, and taking necessary precautions with respect to milk of doubtful character.

In a second paper Doctor Anderson summarizes the evidence proving that Malta fever may be spread by infected goat's milk.

A peculiar disease, known as "milk sickness," is described by Doctor McCoy. Although fortunately rare at the present time, cases continue to occur in the mountainous sections of Tennessee and elsewhere.

Doctor Stiles shows that so far as the zoo-parasitic diseases of man are concerned, there is little to fear concerning the presence of such parasites in milk.

Statistical studies of mortality and morbidity, as influenced by milk, have been made by Doctor Eager. He gives figures to prove that the high infantile mortality may be attributed almost entirely to impure milk.

Doctor Wiley discusses the subject of ice cream, its use as an article of food, its composition, the extent to which it may be contaminated or adulterated, and the result of such contamination upon the public health. He also refers to the established standards governing its manufacture, and presents evidence to show their reasonableness both to the manufacturer and consumer.

Doctors Kastle and Roberts give a general survey of our present knowledge regarding the physical and chemical characteristics of milk, as well as the chemical changes in milk brought about by the action of heat and acids; and also those changes accomplished by the action of enzymes and microorganisms. The subject of milk adulteration is also considered. It has been shown, as the result of original investigations, that the milk ferments can withstand a temperature of 60° to 65° C. for some time without material injury. Twelve per cent of the samples of Washington market milk examined were found to be below the legal standard, 3.7 per cent gave evidence of having been watered, and a very large proportion of the samples examined contained appreciable quantities of dirt. None of the samples examined contained artificial coloring matters, and only one contained milk preservatives.