Multiple infections with Treponema pallidum in the rabbit

Abstract

Once it has been demonstrated that under appropriate conditions superinoculation of a rabbit with an advanced syphilitic infection may give rise to a typical primary lesion, 1 the question naturally arises as to whether this second infection is limited in its effects to the local reaction or is capable of further participation in the disease produced.

The problem was approached by a number of experiments. Rabbits infected with strains of low virulence were reinoculated with strains of high virulence after the original infection had become well established. In general, the primary inoculation was made in one or both testicles while the second was intracutaneous on the sheath or at the base of one ear, using equivalent amounts of a testicular emulsion. The infections thus produced were compared with those in a series of control animals. The interpretation of the experimental results was based upon the usual course of the disease produced by each strain with particular reference to the type and severity of lesions and to their time and sequence of occurrence since at a given time and under given conditions these are comparatively constant properties of any given strain.

The experiments up to the present time have yielded a number of instances in which the nature of the infection differs from that ordinarily seen with any one of the several strains employed and this may be illustrated by citing a single example. The two strains used in this experiment have been studied in a large series of animals. The less virulent strain (111) used for the primary inoculation was isolated in the fall of 1919. It has always produced a mild infection with slight primary lesions of short duration and generalized lesions of a minor character consisting of occasional small diffuse or papular lesions of the skin, slight infiltrations about the sheath, a few cases of keratitis and two instances of slight periostitis of the nasal bones.