On the production of generalized syphilis in the rabbit by local inoculation

Abstract

Two of the most striking features of the infection usually produced in rabbits by testicular or scrotal inoculations of well-adapted strains of Treponema pallidum are the marked reaction at the site of inoculation and the total absence of generalized lesions. In fact, these features of the reaction to infection are so conspicuous as to suggest a casual connection between the two, especially when it has been shown that the failure to produce generalized lesions can in no wise be attributed to the absence of a generalized infection or to an insusceptibility on the part of the animal's tissues to react to such organisms. Specifically, it appeared to us that in all probability, the failure to produce generalized lesions was due in a large measure to an inhibitory influence arising from the reaction at the primary focus of infection and that the reduction or suppression of this reaction might be sufficient in itself to permit the development of generalized lesions.

In order to test this hypothesis, three types of experiments were carried out which were intended to compare the effects produced by unilateral and bilateral inoculations, the effects of castration and the effect of suppression of the primary lesions by the use of therapeutic agents. The castrations were done under ether anesthesia.

Effects of Unilateral and Bilateral Inoculation and of Castration. -In the first series of experiments, there were 27 rabbits inoculated in one testicle and 20 inoculated in both testicles, giving a total of 47 rabbits. These were divided into two groups, one of which was castrated soon after the appearance of the primary lesion and the other held as controls. Both groups were kept under observation for a period of 4 months after inoculation.