Vaccination Against Tuberculosis--A Comparative Study in Man and Animals

Abstract

and others3 point to a beneficial effect of previous contact with tubercle bacilli, and another school4 stresses only the detrimental subsequent effects of such first association with the bacilli. Our own results favor the former viewpoint. It is the purpose of this paper to present briefly the findings on which this conclusion is based. It is not generally recognized that tubercle bacilli, viable or nonviable (heat or chemically killed), possess a definite and immediate quantitative tissue destructive action. This action with viable bacilli is influenced by the factor of the ability of the bacilli to multiply in the tissues of the host. We have found5,6 that viable avirulent human or avirulent bovine tubercle bacilli produce no more local tuberculous skin lesion, when injected intracutaneously into a species of animal susceptible to the type of tuberculosis in question, than an equivalent amount of nonviable tubercle bacilli of the same strain. Such viable avirulent tubercle bacilli when injected intracutaneously in small amounts disappear in viable form from the site of inoculation and possess little tendency to disseminate to internal organs. In contrast, the virulent tubercle bacillus, pathogenic for the species of animal in question, produces a chronologically progressive skin lesion with multiplication of tubercle bacilli at the site of inoculation as well as at the site of dissemination to the organs. Relatively large amounts (five milligrams in fine suspension) of avirulent tubercle bacilli injected intravenously into the guinea pig result in a transient acute splenomegaly without producing ultimate gross tuberculous changes in any of the organs. This amount of avirulent bacilli given intravenously