Interim report of the Royal Commission appointed to enquire into the relations of human and animal tuberculosis; and : Second interim report of the Royal Commission appointed to enquire into the relations of human and animal tuberculosis.
- Great Britain. Royal Commission on Tuberculosis (Human and Bovine)
- Date:
- 1904 [and] 1907
Licence: In copyright
Credit: Interim report of the Royal Commission appointed to enquire into the relations of human and animal tuberculosis; and : Second interim report of the Royal Commission appointed to enquire into the relations of human and animal tuberculosis. Source: Wellcome Collection.
Provider: This material has been provided by London School of Hygiene & Tropical Medicine Library & Archives Service. The original may be consulted at London School of Hygiene & Tropical Medicine Library & Archives Service.
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![former animal being more susceptible to the bacillus, the tissues having less power of resistance than in the latter animal. Hence it is not the absolute dose, the absolute number of bacilli, which supplies a determining factor, but the dose in relation to the susceptibility of the animal. Again, the effects of emulsions are consistently greater than are those of cul- tures estimated to contain the same number of bacilli. Certain conditions obtain either in the bacilli themselves or in the medium in the midst of which the bacilli are living whether in a culture or in an emulsion; and these bring it about that the same number of bacilli are more effective in the one case than in the other. It will be understood, therefore, that we are not in a position to state absolutely what is the minimum dose which will produce a rapidly fata] generalised progressive tuberculosis in the bovine animal when injected sub- cutaneously. We have no means of quantitatively appreciating the other determining factors. Our results show that with each of the strains examined, 50 mgrs. of culture, roughly calculated to contain between 200,000 and 250,000 million bacilli, always produce the above fatal results. Such a dose overrides everything. A dose of 10 mgrs. culture, i.e., 40,000 to 50,000 million bacilli, is often fatal but not always; this dose seems to leave room for the play of individual susceptibility. And the smallest dose of culture, 5 mgrs., which led to fatal progressive tuberculosis was calculated to contain 20,000 to 25,000 million bacilli, while the smallest determined effective dose of emulsion contained only 5,500 bacilli. In striking contrast to the ease with which, an adequate dose being used, a rapidly fatal progressive tuberculosis is set up in the bovine body by tubercle bacilli subcutaneously injected, is the difficulty of producing the same result by feeding. Turning now to the effect on animals other than bovine, our results show that the bacillus of bovine tuberculosis introduced either by injection or by feeding can set up general progressive tuberculosis in guinea-pigs, rabbits, pigs, goats, cats, dogs, and monkeys ; and the list might probably be much extended. It can undoubtedly produce its full effects on animals other than bovine, though more readily on some kinds than on others. The question naturally presents itself:—Is the bacillus of bovine tuberculosis as effective on these other animals as it is on the bovine animal ? Now it is difficult to compare exactly the effects produced in one kind with those pro- duced in another kind of animal. Where the two kinds differ widely in size we may affect an exactitude by using for comparison a unit of body weight, comparing, for instance, the effects of so many bacilli per kilo, of body weight; but such an exactitude is probably illusory. And in any case the conclusions arrived at on the point in question can only be approximate. The results which we have obtained do, however, point very strongly to the conclusion that the bacillus of bovine tuberculosis is not only as effective but even more effective in causing tuberculosis in some of the above animals than in the bovine animal itself. The fact that very few bacilli, though we do not know the exact limit of paucity, introduced subcutaneously into the body of a guinea-pig will so certainly produce generalised tuberculosis that the experiment may be trusted to test the presence of the bacillus, while many thousands at least are needed to ensure the same result in the bovine animal, cannot be explained by the mere difference in size between the two kinds of animals. We are driven to the conclusion that the guinea-pig is more susceptible to bovine tuberculosis than is the bovine animal itself. And this conclusion is supported by the fact that the bacillus of bovine tuberculosis given to the guinea- pig by the mouth, usually or at least often produced generalised tuberculosis even though the dose was small, whereas in the bovine animal feeding with even relatively large quantities produced as a rule only a limited local tuberculosis. Again, the difference in size between a pig and a calf is quite insufficient to ex- plain the facts that general tuberculosis is much more readily produced by feeding and that, in subcutaneous injection, a much smaller dose gives rise to generalised tuberculosis in the former than in the latter. A similar conclusion may be drawn from the results obtained with monkeys. All these three kinds of animals—guinea-pigs, pigs, and monkeys—seem to be more susceptible to the action of the bacillus of bovine tuberculosis than is the bovine animal itself. The bacillus of bovine tuberculosis is not so constituted as to act on bovine tissues only, for it can give rise to tuberculosis in many animals other than bovine ; 77. P. o](https://iiif.wellcomecollection.org/image/b21366366_0027.jp2/full/800%2C/0/default.jpg)
