Appendix to Third report of the Commissioners : minutes of evidence, April to July, 1907.
- Great Britain. Royal Commission on Vivisection (1906)
- Date:
- 1907
Licence: Public Domain Mark
Credit: Appendix to Third report of the Commissioners : minutes of evidence, April to July, 1907. Source: Wellcome Collection.
217/272 page 211
![lutely prevented, and the great majority of wounds where contamination with soil has rendered them liable to infection with tetanus bacilli can be success- fully dealt with. In the recent South African War only three cases of tetanus occurred. Further, the animal experiments of Behring and Kitasato (1890) (loc. cit.) showed that by repeated small but increasing doses of the soluble tetanus toxin, animals can be rendered immune to this poison, and that the serum of such highly immunised animals renders inoffensive the tetanus poison with which it is mixed. The serum of horses which have been gradually accustomed to this poison until they support, without ill-effects, quantities many thousand times that required to kill horses not so treated, is a valuable therapeutic agent in human and veterinary surgery. This subject will, however, be referred to in greater detail later. 11654. You now have something to tell us about plague ?—Plague is a disease of great antiquity, and previously seen by Nicolaier in 1884, in the local wound some of the earliest human documents extant record the ravages of this pest. During 1905, 1,040,429 persons succumbed to plague in India. Over 350,000 deaths occurred in the Punjab alone (official returns). In some of the villages of this province 75 per cent. of the population were destroyed in two years. The mortality amongst Asiatics varies between 70 and 80 per cent., and amongst Kuropeans at the present time it is over 35 per cent. of those attacked. As long as the causation of plague was not comprehended, and the means by which it is spread were unknown, suitable preventive measures could not Se rationally prescribed. Consequently, even in recent times, wealth and human effort have been squandered in directions that have led to no useful result. The constant association of a mortality of rats and mice, with outbreaks of plague amongst human beings, has heen forced upon the minds of many ancient people, and is found to exist among many primitive races of mankind at the present time. The true significance and importance of this observation could not, however, be realised until the causation of the disease was dis- covered by Yersin and Kitasato (Lancet, 1894) in Hong Kong in 1894. These observers found a bacillus constantly present in the swollen lymphatic glands (buboes) of patients suffering disease, and they succeeded in grow- ing it upon artificial media. Inoculation of the cul- tures of this organism into animals reproduced the disease with all its characteristic symptoms. Once the cause of the disease was known, it was easy to deter- mine that the disease from which rats and mice simul- taneously suffered was also plague. Al] the conditions, favourable and unfavourable, to the existence of the infective agent, could now be studied, and the means whereby the infection leaves the bodies of persons or animals dead of the disease, could be determined. The relationship in time and space between human out- breaks and disease in rodents could be worked out, and the influence of epidemics amongst rats in the spread of the disease among human beings determined. The relationship of rat plague to human plague has peen found to be of such a character as (taking into consideration the small extent to which bubonic plague is infectious from man to man) to indicate in the strongest manner that the spread of the disease in man is conditioned almost entirely by the occurrence of plague amongst rats in his vicinity. The Commission at present investigating the question of the spread of plague in India, have, by extensive experiments upon animals, succeeded in showing that the infection is carried from rat to rat by the agency of the fleas in- festing these animals (J. of Hygiene, 1906 and 1907, special numbers). By the same agency they have been able to produce epidemics amongst other animals, guinea pigs and monkeys; whereas all other ineans failed to give rise to the epidemic spread of the disease. The Indian rat flea also feeds upon man when his natural prey is not available, so that a possible, and indeed probable, means whereby the infection is carried from rats suffering from the disease, to mankind has been established. Further experiments carried out in houses or huts, where many cases of plague occurred, have shown that animals (guinea pigs or monkeys) are attazked by the disease when placed in such infected huts, without protection from fleas; but if the simplest means is adopted to prevent the fleas from reaching the animals, by a gauze covering, or a layer of sticky paper wider than a flea can jump, or by suspending 349, 211 the cage at a distance from the floor greater than a flea can leap, they have in no case contracted plague. 11655. Whose are these experiments with fleas ?— The experiments of the present Commission which is investigating the plague in India, of the Advisory Committee of which I have the honour to be a member. 11656. Do these fleas which carry the plague from one to another get the plague themselves ?—No, they do not suffer in health apparently. The plague microbes merely multiply inside their alimentary canal, without apparently detrimentally affecting them in the least. It need hardly be insisted upon that the complete comprehension of the spread of the disease under natural conditions is essential to successfully devise preventive measures. Without such knowledge our efforts will, in all probability, be misdirected. A knowledge of the causation of plague has enabled a useful method of protective inoculation to be devised. Efforts towards the production of a curative serum have unfortunately, so far, been disappointing, as the means employed have not produced an anti-serum of sufficient potency. 11657. Your next head of evidence is the importance of experiments on animals in the diagnosis of infec. tious diseases ?—The value of a means of arriving at an early diagnosis in the case of infectious disease of man and animals is considerable, because the physician or veterinary surgeon, is, as a rule, unable to form a diagnosis until the disease has developed. This may mean a delay of weeks, or even months, during which. precious time is lost, and precautions to prevent the spread of the disease omitted. Moreover, in mild or latent cases of a disease, it may be quite impossible to arrive at a diagnosis by ordinary clinical means. The advantages of early bacteriological diagnosis are not confined to the patient, but are of importance to the community, or the owner of stock or stable, for upon the early recognition and segregation of cases of infectious maladies, the probability of successfully stamping out the disease depend. Mild or abnormal cases of disease may be equally endowed with the power of spreading the infection. Recent researches into,the epidemiology of diphtheria, typhoid, and cholera, have indeed proved, that persons convalescent from these diseases and in all respects perfectly healthy, may be innocent agents distributing broadcast these various infections. In many cases a bacteriological diagnosis of a disease can only be made by direct appeal to animal experiment; but in quite a number a simpler method by which this is avoided, but which has been arrived at in the first instance by experiments upon animals, can be employed. As instances of such methods I cite: (1) The recognition under certain con- ditions, of tuberculosis, anthrax, relapsing fever, diphtheria, syphilis, gonorrhoea, plague, and sleeping sickness, by observations upon the morphological staining and growth characters of the organisms con- tained in the material submitted to examination. (2) By taking advantage of the fact that the human and animal body when infected with certain diseases, e.g., typhoid fever, cholera, and malta-fever, elaborates substances in the blood which have the property of causing the individual organisms of these diseases to aggregate together into clumps, so-called agglutinins. As this agglutinating action is within certain limits only exercised upon the particular species of microbe which is responsible for the disease, a diagnosis may be arrived at. For this purpose a single drop of blood from the patient is adequate. (3) In the case of cholera and typhoid infections a further substance is present in the blood serum, which has the power of killing and dissolving up the respective bacilli. This action is specific, so that the test applied with a few drops of blood can be used for diagnosis. (4) Nos. 2 and 3 can microbes suspected of being typhoid or cholera, which have been separated from water or the dejecta and other excretions or discharges from the human body. In this case cultures of these organisms are submitted to the action of a small quantity of the serum, obtained from an animal immunised against infection with typhoid or cholera microbes. (5) The diagnosis of tuberculosis in cattle and of glanders in horses, in the early stages of the disease, when it cannot be recog- nised by clinical signs, can be made by the infection of a small quantity of tuberculin or mallein respectively. Tuberculin and mallein are the products which are formed by the growth of tubercule and glanders bacilli 2D 2 Mr. C.J. Martvn, M.B., D.Se., F.R.S. 10 July 1907.](https://iiif.wellcomecollection.org/image/b32182181_0217.jp2/full/800%2C/0/default.jpg)
