TUBERCULIN. Tuberculin, the name given to various specific substances obtained from artificial cultures of the tubercle bacillus, discovered by Robert Koch in 1890. Koch wrote : "Tuberculin will become an indispensable agent in the diagnosis of tuberculosis, especially in the early stages of phthisis" and "Much more important is its curative action." As a diagnostic agent tuberculin has been proved by the post mortem examinations of Mettetal, Binswanger, Mikulicz and France to be a trustworthy means of detecting the presence of tuberculous lesions in the body. In 1908, W. Camac Wilkinson wrote, "I hold that the specific reaction only occurs when there are living tubercle bacilli somewhere in the body." (Weber Parkes Prize Essay, p. 127) The trend of scientific opinion is in this direction. In all chronic tuberculous diseases of the lungs, bones, joints, serous membranes and elsewhere, injections of tuberculin prove, not merely that infection with tubercle bacilli has occurred at some time, but that living and active tubercle bacilli are somewhere at work in the tissues and therefore tuber culosis exists. In fact tuberculin alone can prove in the early stages of this disease that a tuberculous focus exists.
The value of tuberculin in treatment is far more difficult to assess in a disease so capricious, so inconstant and so treacherous as phthisis. Effects due to the disease are often ascribed to the remedy. "Post hoc, propter hoc." No opinion is sound unless a
large number of cases have been treated and then controlled by after examinations for at least five years. Controlled in this way in a series of early and moderately advanced cases of phthisis, all having tubercle bacilli in the phlegm, 68% were alive 8-10 years after treatment and many of them were well.
Tuberculin treatment is the only method that can be applied in the aggregate, because at tuberculin clinics, treatment for a year need not cost more than L I o–L I5 per case ; ambulant treatment is feasible and quite safe ; there is no waiting list ; the convenience of workmen is studied ; in 75% of all cases there is no need for the patient to give up work or leave home. The method is simple, economical and wastes little time. Every patient should be treated in as early a stage as possible.
Wilkinson has in recent years applied tuberculin to the diagnosis and treatment of various diseases of the eye, notably conjunc tivitis, iridocyclitis, scleritis, episcleritis and even retinitis. The results have been remarkable. In several patients sight which was lost has been restored; in many cases, tuberculosis was not sus pected. It is hoped that the results of tuberculin in the diagnosis and treatment of diseases of the eye, may restore it to the place assigned to it by Robert Koch in 1890. (W. C. W.)