This matter is of special importance in regard to the danger of conveying tuberculosis to infants through raw milk. That this may happen is generally accepted as proved (although Koch, at the Tuberculosis Congress held in London in 1901, made an emphatic statement to the contrary), and State boards of health in this country are everywhere endeavouring to secure proper legislative authority to inspect and condemn tuberculous cattle.

Milk infected with tubercle bacilli when fed to animals has been shown to produce primary intestinal and mesenteric tuberculosis, and this may occur in infants. H. C. Ernst produced tuberculosis in pigs by feeding them milk from tubercular cows when the latter had normal udders. Cow's milk may contain tubercle bacilli when the disease is located in the lungs of the animal (Ernst). It is possible that this is the case with the milk of tubercular mothers, although it is not yet an established fact. The danger to the infant is less in such cases, for the disease in the mother is usually recognised in time to discontinue breast nursing.

It has been estimated in regard to the Eastern States that 15 per 27 cent of the common dairy stock is tubercular. Stall-fed animals who live in filthy barns and get but little exercise show the largest percentage of infection. In healthy adults the gastric juice may succeed in destroying tubercle bacilli swallowed with such food, and no doubt it often does so. Fortunately the milk of all tubercular cows does not contain the bacilli, but it is almost certain to do so when the udders become involved in the disease. In large dairies the cows should be given the tuberculin test once in six months, and if they respond should be condemned as milk producers. (Conference of State Boards of Health, 1898).

In infants who live largely upon raw milk, and whose gastric digestion is less vigorous than that of adults, mesenteric tuberculosis is relatively more common.

Tubercular Meat Infection

Tubercular meat usually proves less virulent than raw milk, probably because it is subjected to thorough heat in cooking, but all the bacilli are not invariably killed by imperfect cooking, and infected meat or milk should on no account be eaten. This fact is being gradually appreciated by the public, and meat inspection at abattoirs is now much better regulated by law and supervised by local health boards than formerly; but Billings says that "probably one half of one per cent of the beef sold in market comes from animals in whom tubercle existed at the time of death".

All slaughtering should be done in public abattoirs under competent inspection, and not only should the animals be examined before killing, but the meat should be inspected afterwards.

The Bacillus tuberculosis has been found not-only in the meat or muscle of the animal butchered, but in the liver, kidneys, and other viscera. It has also been seen in peripheral caseous nodules growing upon fowls (Sibley), and barnyard fowls have been known to eat tuberculous sputum carelessly expectorated within their reach. The bacillus is not killed by salting meat nor always by its digestion in the stomach. Moreover, salt meat is not so thoroughly cooked as fresh meat, as a rule.

Theobald Smith (Annual Report, Massachusetts State Board of Cattle Commissioners, 1897) says it is doubtful whether the muscles of cattle ever contain bacilli, but the latter are liable to be smeared over the meat by the butcher's knife fresh from cutting into a tuberculous lymphatic gland or lung. According to this writer, there are several varieties of tubercle bacilli as found in different animals, which show decided differences in morphology and pathogenic activity, but their morbific processes appear to be substantially the same. He suggests that the bovine and human varieties may under some conditions pass into one another, but he denies that cattle are susceptible to human tuberculous sputum. He believes that the danger of infection of man through milk and meat is greatly exaggerated, for while human tuberculosis has been decreasing for a whole generation, that of cattle, at least until very recently, has been on the increase. One or two curious cases are recorded of fowls dead of tuberculosis acquired by pecking at human tuberculous sputum, and Peter Paterson, of Glasgow, reports a death from eating tuberculous poultry.

D. E. Salmon, Chief of the United States Bureau of Animal Industry, in a report covering the two years ending June 30, 1899, says:

"The number of condemnations per 10,000 animals slaughtered was:

Cattle.

Sheep.

Swine.

Whole carcasses

22

7.5

24

Parts of carcasses

26

0.6

13

Total

48

8.1

37

"Of the whole carcasses of cattle condemned 26 per cent were affected with actinomycosis and 36 per cent with tuberculosis. Of the parts of carcasses of cattle condemned 13 per cent were affected with actinomycosis and 1 per cent with tuberculosis. Nevertheless these diseases are surprisingly rare, as only 8.1 carcasses per 10,000 animals were condemned for tuberculosis, and 9.2 per 10,000 for actinomycosis. Tuberculosis is one of the principal diseases of swine, but is found only in 1.3 carcasses per 10,000 animals. Tuberculosis in sheep is a rare disease. Including tuberculosis and pseudotuberculosis, which are given together in the reports, there are specified but 6 per 100,000 sheep inspected.

" The beef-cattle which come from large abattoirs are singularly free from tuberculosis, only 1 animal in 1,500 or 2,000 being affected to an extent to cause condemnation of any part of the carcass. Dairy cattle may be affected to the extent of 5 to 10 per cent! In Europe, the slaughter-house statistics show from 20 to 50 per cent of all cattle slaughtered to be affected with tuberculosis".

Other Infections

Meat from animals dead of various acute diseases is sometimes eaten, and if well cooked it may be harmless, but it is not good food, and no part of any animal suffering from the foot-and-mouth disease (or cattle plague), rabies, glanders, actinomycosis, anthrax, septicaemia, swine plague, sheep or cow pox, pneumonia, trichinosis, or tuberculosis should ever be eaten.

Typhoid And Cholera Infection

Typhoid infection is undoubtedly conveyed through milk which has been diluted with water infected from a barnyard well or cesspool, or which has been placed in cans rinsed in such water. Hankin describes cases of this fever derived from eating dahi, a curdled milk made by East Indian confectioners. Fraenkel found that typhoid bacilli may live in acid buttermilk. The typhoid bacillus may live for several days in fresh milk without multiplying.

Three hundred and eighty-six cases from milk infection occurred at Stamford, Conn., in May, 1895. Another epidemic occurred in York, Pa., in 1899, and two extensive epidemics were traced to this source in Philadelphia in 1903, the milk dealers having been found to have cases of typhoid fever in their own families.

At Coseley, near Birmingham, England, five cases of typhoid fever were traced to infection from ice cream.

Typhoid infection through contaminated drinking water has been already mentioned (p. 39). Even brushing the teeth with such water or using it as ice may convey the bacilli into the body.