Outlines of Dairy Bacteriology, 8th edition / A Concise Manual for the Use of Students in Dairying

ly called to this relation by Ernest Hart,[78] who in 1880 compiled statistical evidence showing the numerous outbreaks of various contagious diseases that had been associated with milk infec

tive importance of milk as a facto

d grow in milk, even though the normal milk bacteria are also present. Moreover the recognition of the presence of such pathogenic forms is complicated by the fact that often they do not alter the appearance of the milk sufficiently so that the

may be grouped with reference to their relation toward milk into

being transmitted directly from a diseased an

ot for cattle which are capable of thriving

arasitic life in the animal, developing in the udder, and so infect the milk supply. It may, of course, happen that diseases towar

f it happens to find its way therein. In such cases milk indirectly serves as an agent in th

seased milk supply is tuberculosis, but in addition to this, foot and mouth disease (aphthous fever in

this way. In addition to these diseases that are caused by the introduction of specific organisms (the causal organism of scarlet fever has not yet been definitely determined), there are a large number of more or less illy-defined troubles of an intestinal character that occur e

E FROM ANIMAL TO MAN

mportance. It is now generally admitted that the different types of tubercular disease found in different kinds of animals and man are attributable to the development of the s

s able to make but slight headway in cattle. This would indicate that the danger of cattle acquiring the infection from man would in all probability be very slight, but these experiments offer no answer as to the possibility of t

of this organism. The results obtained in the case of all animals tested show that the virulence of the two types was much different, but that the bovine cultures w

se have occurred with persons engaged in making post-mortem examinations on tuberculous animal

noteworthy that this phase of the disease is quite common in children especially between the ages of two and five.[84] It is difficult to determine, though, whether primary infection occurred through the intestine, for, usually, other organs also become involved. In a considerab

many regions has revealed an alarmingly large percentage of animals as affected. In Denmark in 1894 over forty per cent were diagnosed as tubercular. In some parts of Germany almost as bad a condition has been revealed. Slaughter-house statistics also show that the disease has increased rapidly since 1890. In this country the disease on the average is much less than in Europe and is also very irregularly distributed. In herds where it gained a f

rculous udder, showing extent

not materially altered at first, but as the disease progresses the percentage of fat generally diminishes, and at times in the more advanced stages where the physical condition of the udder is

licting and further information is much desired. Some have asserted so long as the udder itself shows no lesions that no tubercle bacilli would be present,[86] but the findings of a considerable number of investigators[87] indicate that even when the udder is apparently not diseased the milk may contain the specific organism as revealed by inoculation experiments upon animals. In some cases, however, it has been demonstrat

nd pigs which may be fed on the skim milk. The very rapid increase of the disease among the swine of Germany and Denmark,[8

s incapable of growing at normal air temperatures. There is, therefore, no danger of the germ devel

test, it is quite impossible to foretell how long it will remain free. As the disease becomes more generalized,

fe. Whether it is necessary to do this or not if the milk is made into butter or cheese is a somewhat different question. Exclusion or treatment is rendered more imperative in milk supplies, becaus

the milk, and inasmuch as no growth can ordinarily take place in these products the danger is minimized. Moreover, the fact that these foods are consumed by the i

butter, but this fact is not so surprising when it is remembered that a very large fraction of their cattle show the presen

ed in the same way as the tubercle organism. Differentiation between the two forms is rendered more difficult by the fact that this tubercle-like organism is also capable of producing in animals lesions that stimulate th

d that the true tubercle bacillus is able to retain its vitality

r the milk of any reacting animal actually contains tubercle bacilli or not, still the interests of public health dema

must be considered, viz., the presence of conditions permitting of the formation of a "scalded layer," for as Smith[91] first pointed out, the resistance of the tubercle organism toward heat is greatly increased under these conditions. If tuberculous milk is heated in a closed receptacle where this scalded membrane cannot be produced, the tubercle bacillus is killed at 140° F. in 15 to 20 minutes. These results which were first determined by Smith, under laboratory conditions, and confirmed by Russell and Hastings,[92] where tuberculous milk was heated in commercial pasteurizers, have also been verified by Hesse.[93] A great practical advantage which accrues from the treatment of milk at 140° F. is that the natural creaming is practically unaffected. Of course, where a higher temp

taneous introduction of a number of organisms, and in the case of tuberculosis, especially that produced by ingestion, this number is thought to be considerable. Gebhardt[95] found that the milk of tuberculous cows, which was virulent

ith the separator slime. Moore[97] has shown that the tubercle bacilli in an artificially infected milk might be reduced in this way, so as to be

lowed where pasteurization or sterilization is not desired. In dairies where the keeping quality is dependent upon the exclusion of bacteria by strin

istinctively an animal malady, it is also transmissible to man, although the disease is rarely fatal. The causal organism has not been determined with certai

able to produce the symptoms of the disease, the mucous membrane of the mouth being covered with the small vesicles that characterize the malady. It has also

in which it has been shown that the virus of the disease is at times to be found in the milk supply,

d, and often pus is present to such a degree as to give a very disagreeable appearance to the milk. Pus-forming bacteria (staphylococci and streptococ

O MAN THROUGH INFECTION

e growth of many pathogenic species even at ordinary temperatures. Not infrequently, disease-producing bacteria are able to grow

let fever and cholera, together with the various illy-defined intestinal troubles of a toxic chara

ed directly from animals because cat

ng influences after it is drawn from the animal, and so give opportunity for the developm

the so-called cases of "walking typhoid," this danger is emphasized. It is noteworthy in typhoid fever that the bacilli frequently persist in the urine and in diphtheria they often remain in the throat until after convalescence. In some cases infection has been tra

t to a sick person, and also assist in the handling of the milk, either in milking the animals or caring for the milk after it has be

typhoid fever, and the use of water at normal temperatures, or even in a lukewarm condition, give conditions permitting of infection. Intentional adulteration of milk with water inadvertently taken from polluted sources has caused quite a number

aminated water. This method of infection would only be likely to occur in case of typhoid

the creamery, the infective agent remaining in the skim milk after separation and so polluting the mixed supply. This condition is more likely to prevail with typhoid because of the greater tolerance of

ed in other ways. Several outbreaks of typhoid fever have been traced to the use of ice cream where there were strong reasons for believing that the milk used in the man

he case of polluted waters, except that the difficulties of the problem are much greater in the case of milk than with water. The inability to readily separate the typhoid germ, for instance, from the colon bacillus, an organism frequently found in milk, presents technical difficulties not easily overcome. The most potent reason of failure to f

le of withstanding considerable amounts of acid, and consequently finds even in raw milk containing the normal lactic acid bacteria conditions favorable for its growth.[113] Ability to grow under these conditions can be shown not only experimentally, but there is abundant clinical evidence that even a slight infection often

tensils are infected in one way or another.[114] Second in importance is the carryin

on of acids. Kitasato[115] found, however, that it could live in raw milk from one to four days, depending upon the amount of acid present. In

umber of sailors, upon reaching port, secured a quantity of milk. Of the crew which consumed this, every one was taken ill, and four out of ten died, while those w

eria. Swithinbank and Newman[117] cites four cases in which the causal organism has been isolated f

infection from patient on account of the long persistence of this

m of scarlet fever is not yet known, yet the origin of a considerable number of epidemics has been traced to polluted milk supplies. Mil

d directly is explicable on the theory that cows' milk is the carrier of the infection, because in many cases it is not consumed until there has been ample time for the development of organisms in it. Where milk is pasteurized or boiled it is found that the mortality among children is greatly reduced. As a cause of sickness and death these diseases exceed in importance all other specific diseases previously referred to. These troubles

ances, tyrotoxicon, was isolated by Vaughan[123] from cheese and various other products of milk, and found to possess the property of producing symptoms of poisoning similar to those that are noted in such cases. He attributes the production of this toxic effect to

TNO

nt. Med. Cong., Lon

Med. Rec., M

c and infectious milk, giving a very complete bibliography of 180 numbers. They append to Hart's list (which is published in full) additional outbreaks which h

, Journ. of Expt.

t. Stat., June, 1899; Ravenel, Uni

Vet. Arch., Dec. 1897; Hartzell, Jo

it. Med. Journ.

arliest phases of the disease, tuberculin causes a temporary fever that lasts for a few hours. By taking the temperature a number of times before and after injection it is possible to readily recognize an

n. 1895, 1:937; Nocard, Les

Milch Kunde und M

ag, Milch Z

ri, Arb. a. d. Kais. Ges. Amte, 1898, 14: 1; H

ch, Zeit. f. Hy

Journ. of Expt.

stings, 18 Rept. Wi

eit. f. Hyg.,

n Denmark is made from cream that has been paste

Virch. Arch.,

. Ges. Amte, 1891, 7:269; Ba

ook of U. S. Dept.

p. 642; Weissenberg, Allg. med. Cent. Zeit., 1890

hr., 1893, No. 27; Fr?hner, Zeit f.

che Zeit. f. Thier

, Bull. Gén.

ahr. f. offentl. Gesundh

leisch und Milch

teljahresschr. f. offentl. G

, London Practiti

in, Boston Med. & Surg.

hila. Med. News

London Lancet,

Med. Journ.,

. Health Rept.

oner, 1892, 49:141; Munro, Br

rit. Med. Journ

eitsamte, 1889, 5:303) finds it capa

yphoid epidemics. He found 71 per cent. due to infected drinking water, 17

b. a. d. Kais. Ges

ondon Practition

nd Newman, Bacterio

Ellerhorst. Milch Zeit

y, Hyg. Rund.

Deutsch. med.

Zeit., f. Hyg.

ies from the Rockefeller Inst

ie, 10:146; 9 Intern. Hyg. C

d Perkins, Arch.

7, 50:570) report three outbreaks at Long Branc