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APPENDIX. Report received from Professor 0. E. Hercus, D.5.0., 0.8. E., M.D., 8.D.5., D.P.H., Professor or Bacteriology and Preventive Medicine, Otago University. (1) The Value of Tuberculin as an Immunizing Agent against Pulmonary Tuberculosis. There is a vast literature relating to this subject. Every possible modification of tuberculin has been tried with the object of producing a prophylactic immunizing agent against tuberculosis, including pulmonary tuberculosis. The results have been in the main negative, although Petroff and his coworkers make claims that they can confer a certain degree of immunity against tuberculosis to guineapigs by means of what is practically a tuberculin vaccine. The present trend of immunological thought is, however, in the direction that, as in smallpox, prophylactic immunization can only be secured by the use of attenuated living tubercle bacilli which would produce a mild and retrogressive infection. The B.C.G. vaccine is being widely used throughout Europe, and in the January number of the Bulletin cle VAcademie de Medecine the results of 52,772 immunizations are given for a period extending from July, 1924, until December, 1927. The children were exposed to an infected environment, and careful control groups were observed. The mortality in the vaccinated group was less than half that in the unvaccinated group. Although the method must still be regarded as in its experimental stage, the findings are distinctly significant. (2) The Value of Tuberculin in the Treatment of Pulmonary Tuberculosis. If tuberculin was really a sovereign remedy in the treatment of pulmonary tuberculosis it would be a reasonable assumption, after making due allowance for individual prejudices, that it would be a more or less routine treatment throughout the world. It is common knowledge that this is not so, and that even where it is used there is no uniformity in dosage and methods of administration. Experimental work on animals shows that the tubercle bacillus is too feebly antigenic, and any antibodies which can be demonstrated are not considered to have any curative effect. The principle use of tuberculin in treatment, it is generally admitted, is due to the hyperemia which its injection produces around infected foci. This chronic congestion, long continued, produces a fibrosis to which its therapeutic action can be ascribed. There can be little doubt that in properly selected cases in experienced hands this mechanical action at the site of infection may be produced with benefit to the patient. It is also fairly clear that non-specific agents, such as milk, &c., in larger doses, may produce the same end result. 19th June, 1928. C. E. Hercus. Report received from Dr. P. P. Lynch, M.8., Ch.B., Univ. N.Z., Pathologist, Wellington Hospital. (1) The Value of Tuberculin as an Immunizing Agent against Tuberculosis. Immunity in tuberculosis is best acquired by infection during childhood. If the infecting dose is small, and not repeated too often, cure of the lesion results with the development of a varying degree of immunity to subsequent infections. The chief difficulty in this, the natural process of immunization, is that the dosage can in no way be regulated. Calmette and Guerin have attempted to overcome this difficulty by using an attentuated strain of tubercle bacillus and inoculating the children of tuberculous parents. The children, during the period of inoculation or immunization are kept as free as possible from other infection. There is no evidence that tuberculin used in the same way has any power of conferring immunity. Tuberculin is quite a different reagent from living strains of bacilli, whether attenuated or not. So far as I know, no attempts have been made to immunize non-infected persons by means of tuberculin. Treatment of an already-infected case with tuberculin cannot be referred to as immunization. (2) The Value of Tuberculin as a Therapeutic Agent in Tuberculosis (Pulmonary). I have often been consulted about the use of tuberculin in cases of phthisis, and I have always held the view that such treatment is not advisable. The natural process of cure by fibrosis should not, I think, be interrupted by any stimulus likely to lead to breaking down and spread from a partly healed focus. In addition, it is extremely difficult to state which of the tuberculins has the most to recommend it, or which, for that matter, is the least dangerous. 19th June, 1928. P. P. Lynch. Report received from Dr. R. E. Bevan-Brown, M.A. (Oamb.), M.8., Ch.B., Univ. N.Z., ActingPathologist, Auckland Hospital. (1) The Value of Tuberculin as an Immunizing Agent. This, as it stands, implies the immunizing of a non-tuberculous subject against subsequent tuber culous infection. There is no evidence that dead tubercle bacilli or their products can produce any appreciable immunity. All the evidence is to the contrary. Behring, in 1902, and since then many other workers, have shown that only living tubercle bacilli can confer this : these bacilli may be attenuated or

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