Significance of Spiral Organisms Found, after Treatment, in Late Human and Experimental Syphilis

Abstract

On the basis of their findings reported in two previous papers, the authors concluded that the spiral organisms found in the lymph nodes and the cerebrospinal fluid of rabbits and of treated patients are the same as those seen in late untreated experimental syphilis and are considered to actually be Treponema pallidum. These organisms have "conserved their vitality" that is, are living, buthave lost all or most of their virulence. Whether or not this loss of virulence is permanent is impossible to say. In untreated experimental syphilis, as the infection grows older, the morphology of T. pallidum found in smears from lymph nodes becomes pregressively less and less typical. It is probable that they are in fact T. pallidum and their presence explains the persistence of positive reaginic and treponemal serologic tests. In untreated experimental syphilis, lymph node transplants to fresh animals are progressively less and less successful as the infection ages. In animals and in men treated late in the disease, the failure of these transplants does not necessarily exclude the persistence of some T. pallidum. Cortisone can reactivate latent syphilis in rabbits. In two out of 12 rabbits which had been treated and then given cortisone, classical lesions of late syphilis were found. In late human syphilis penicillin and other antisyphilitic treatments are unable to destroy all the T. pallidum. They appear to preserve their vitality but to lose all or part of their virulence. "Bacteriological equilibrium" which corresponds to what we call "clinical cure" can be upset by factors which are as yet unknown.