Infectivity of Trichomonas vaginalis pseudocysts inoculated intra-vaginally in mice.

In addition to the trophozoite, pseudocyst is another morphological form which is recently identified among genitourinary trichomonads. Although, this pseudocyst is competent to divide, its role in Trichomonas life cycle has not yet been confirmed. In this study the ability of intra-vaginally inoculated T. vaginalis pseudocysts to induce trichomoniasis in infected mice was evaluated in comparison to the trophozoites. Pseudocysts formation was induced by using thermal-freezing cycle method. The infectivity of the pseudocysts was proved by the presence of T. vaginalis parasite in mice's vaginal washes inoculated in vitro. SEM proved that the pseudocysts withstood on vaginal tissue for 72 hours post infection without any morphological changes. Although the histopathological studies using H & E, PAS and cathepsin D stain proved that there were no differences could be found between trophozoites and pseudocysts in onset of infection, but the pseudocyst had higher infectivity and invasive effects than the trophozoite. So, T. vaginalis pseudocyst is an active form that can induce trichomoniasis.