The Milk Supply of Large Towns
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Tan., R..- I 670.67af mm=";Iaovaxd&lMuuaBlouxAal THE MILK SUPPLYSUPPLY' OF LARGE TOWNS.TONVNLz. [ML..aoH[KAMM 21, .19030, SO.E BACTERIOLOGICAL CONSIDERATIONS. It would be foreign to our present purpose to go at any length into the subject of the bacteriology of milk. The ON literature is already very extensive, and is growing rapidly. Some general observations are, however, neceseary in order THE MILK SUPPLY OF LARGE TOWNS: that the risks of bacterial contamination to which milk is exposed before it reaches the consumer may be called to ITS DEFECTS AND THEIR REMEDY. mind. The bacteria most characteristic of milk are those which I. produce the lactic and butyric acid fermentations. Of the INTRODUCTORY. lactic organisms which for the most part do not form spores the commropest are the bacillus acidi lactici and the oidium MILK is a delicate and unstable fluid, yet it is the only lactis. Most of the organisms producing butyric acid fer- animal product which is habitually taken raw unless we mentation are sporing species.' According to Klein2 milk -except oysters, a food also under suspicion of being some- received and brought in a sterile vessel from a shop, and kept times a disseminator of disease. It has long been recognized at 370 C., may the next day, or at latest after two days, "1 be that typhoid fever may be disseminated by milk, and more completely clotted and sour, due to the growth and activity of bacillus coli, or it may be decomposed by proteus vulgaris, or ;recently there have been grounds for believing that diph- bacillus mesentericus, or it may be full of gas, clotted with a theria, and perhaps also scarlet fever, may be distributed in large amount of clear whey caused by the growth of the the same way. Recently a great deal of attention has been anaerobic bacillus enteritidis sporogenes." given to the risk of the production of tuberculosis in man- Other microbes producing characteristic effects such as bitter kiind by the consumption of the milk of tuberculous cows, a milk or viscid milk occur, and in milk from cows with inflam- mation of the udder or parts of the udder pyogenic organisms ,risk which, as is well known, Professor Koch considers to be such as the staphylococcus pyogenes aureus, and the strepto- non-existent. The danger, whatever its magnitude, arises in coccus pyogenes, a. brevis and s. longus, may be present. -connexion only with the milk of cows having tuberculous Whether these organisms are ever present in any considerable disease of the udder, and even if it were proved conclusively number except in the milk of- cows with mastitis does not that the bacillus of bovine tuberculosis is seem to have been proved, but they may be present in abun- absolutely dance in purulent matter in milk. A specific microbe innocuous to man, no one will seriously propose that milk has been described as the cause of a specific purulent -should be taken for human consumption from other than inflammation of the udder by Nocard and Mollereau, who healthy cows. applied to it the name "streptococcus mastitidis." Klein But, granted that this condition be observed, there are still has.proposed the name " streptococcus radiatus (pyogenes) " dangers connected with the use of milk as it is now commonly for a microbe associated with a sero-fibrinous massitis in the cow, and producing abscess in guinea-pigs. Many distributed by the trade and consumed in large towns. A otherorganisms frequentlyfound in milkmight be enumerated, large proportion of the fatal cases in the murderous epidemics but it must suffice to refer again to one other, the bacillus -of infantile summer diarrhoea are with good reason attributed enteritidis sporogenes found by Klein in the milk consumed to the consumption of milk in an infective state. by patients who suffered in an epidemic of diarrhoea at St. These dangers are well known, but owing to the supineness Bartholomew's Hospital and in their evacuations, and by Andrewes in other cases of diarrhoea admitted into that of the public are permitted to continue. hospital. It has been found also in water, sewage, manure, Milk may be deliberately adulterated by dishonest traders, and in other samples of milk. Hewlett3 states that it is but the sanitary authorities of the cities and boroughs where generally tq be found in normal dejecta and in dust, and it is distributed have power to deal with such adulterations; that it is probably ubiquitous. It seems probable, however, caumerous prosecutions are, in fact, instituted yearly for the that it is evidence of faecal contamination. It is pathogenic sale of milk which does not reach the official no to guinea-pigs. standard-by We do not propose to enter here upon a discussion of the means exacting. Milk may be " faked" by adding con- occurrence of the infectious agents of tubercle, typhoid fever, -densed unsweetened milk diluted with water to fresh milk cholera, or diphtheria in milk. in such proportions that the final mixture distributed to -customers does not fall below the official standard, a falsifica- CONDITIONS INFLUENCING THE NUMBER OF BACTERIA IN tion MILK. more difficult to detect. But apart from dishonesty and Freshly-drawn milk contains certain germicidal substances the application of " trade secrets," milk from a country farm, which under favourable circumstances, that is to say, when though not adulterated,,may by the time it reaches the con- the milk is kept cool and free from gross contamination, will -sumer's table or the infant's bottle be a highly dangerous check the development of bacteria, and even sometimes- liquid. This is due to want of ordinary cleanliness, and to diminish their numbers. When the temperature of the milk the carelessness with which any and every operation, from is above 5o° F., or when the contamination of the milk is gross, the power of the germicidal substances is quickly ex- the milking of the cow to the delivery of the milk, is too often hausted. -carried out. The cow's udders are soiled and the milker's The whole of the milk drawn at a milking is not sterile, hands are dirty, but neither are washed. The milk pail and but the number of bacteria is small, and- they are contained -churn are inefficiently cleansed. The milk is insufficiently almost exclusively in the part of the milk first drawn. It is cooled or not cooled at all at the farm. The churns are per- probable that, in the intervals between milking, bacteria on the teats grow into the milk ducts, and are washed out at the haps left at a roadside station on the platform for hours in the beginning of milking. Experiments made by Stone for sun. The cans are often not securely closed so that dust can Rotch4 show that milk drawn with minute antiseptic precau.- -enter, and are commonly not sealed, so that they may be tions both as to the milker's hands and as to the cow's teats tampered with by dishonest or careless persons. They may may be absolutely sterile after the udder has been half opened at the railway terminus in a careless way to allow emptied.5 We cannot ask the ordinary milker to dress him- their contents to be measured. Farther for self in a freshly-boiled white suit and cap, to have his hands opportunities and arms thoroughly disinfected with a I in r,ooo mercury contamination occur during the manipulation of the whole- perchloride solution, to wash the cow's udder, teats, flanks, sale dealer and the small retailer. It is not wonderful that sides, groins, and abdomen with the same solution, to dry the milk finally delivered swarms with bacteria indicating for these parts with a freshly-boiled cloth, and to draw the milk the most part excrementitious pollution. into carefully-sterilized bottles, as did Dr. Stone for the All these dangers can be diminished reason- 31anual of Bacteriology, p. 485. London. 1902. enormously by 1H-ewlett, 2 able Journal of Hygiene, vol. i, p. 79. precautions, which experience has proved can be enforced 3 Loc. cit. p. 331. very much to the benefit of the consumer and without unduly 4 Rotch, Pediatric8, the Hygiene and Medical Treatmient of Children, London, the I896. hampering trade. 5 The same rule appears to hold good in the human female. rTX. rmwzux MARCH 21,' 1903.] THE MILK SUPPLY OF LARGE TOWNS. LMmuaAr IovuxNA b79 purpose ot this scientific experiment. But the experiment is Temperature ... 420F. 5o0 F. 55 F. 600 F. 680F. 86° F. worth remembering as proving how little the cow is respons- Bestconditions ... 2,600 II,6oo 18,800 x8o,ooo 450000 1,400,000,C00 ible for the extreme degree of bacterial impurity often to be Usual ,, ... 43,000 8g,ooo I87,000 900,000 4,00,000 14,oo,oo,occ discovered in the milk retailed in large towns. When received the milk taken under the best conditions contained Refinements of this kind and degree are in fact unnecessary. 3,000 bacteria per c.cm., that taken in the usual way 30,000. What we have to aim at is, to quote the words of 'Dr. Rotch,5 Mr. Pakes, then Demonstrator of Sanitary Science and milk "which, while comparatively sterile., has not been steri- Bacteriology at Guy's Hospital, and now Analyst and Bacteri- lized." That this is not an unattainable ideal is now well, ologist to the Transvaal Government, in a paper read before! established.' That it is seldom or never attained is true the Society of Medical Officers of Health in January, Igoo0, that it is commonly departed from so widely that the milk on the application of bacteriology to public health,7 wrote as.