Comparative Pathogenicity of Trichomonas vaginalis and Trichomonas gallinae to Mice. II. Histopathology of Subcutaneous Lesions

Abstract

As a part of continuing investigations into the factors of trichomonad pathogenicity, a histopathologic study has been conducted of subcutaneous lesions produced in C57B1/6J mice by various strains of Trichomonas vaginalis (TVC1, TVC, TV 1, TV 3) and of T. gallinae (JB, TG, YG). The basic mechanisms of reaction are defined and their relationships discussed. Relative pathogenicity of the various strains is assessed on the basis of host tissue reaction. The progressive stage of the reaction to the medium utilized (control) involves the first 8 hr; thereafter, resolution ensues. The process is that of acute inflammation terminating as a well-delineated foreign body reaction. With the introduction of trichomonads, the added duration of the stage of progression continues for periods of time which vary with the strain of organism. In the case of the most virulent strains, this progression is actively continuing at the time of termination of these experiments (2 weeks). The mechanisms of progression in all strains studied are orderly and involve: influx of polymorphonuclear leukocytes; multiplication of the parasites; death of the leukocytes; destruction of host tissues with lysis of the abscess wall, edema of the surrounding tissues, and spreading of the flagellates; influx of leukocytes; remultiplication of the organisms and continuation of the cycle. This cycle progression results in pure mantles of either leukocytes or of trichomonads formed against the inner wall of the injection pocket. Both the precise picture and time sequence vary with the strain of the organism and are related to its pathogenicity. Strains studied which were handled less efficiently by the mouse were also more pathogenic to their natural hosts.