On the view of such new results it is tempting to speculate that frequent Toxoplasma gondii ingestion could lead to a change in the activity of CD4+ CD25+ regulatory cells in the retina and consequently interfere with the equilibrium between the quiescent bradyzoites and the immune state of the eye leading to reactivation of the retinochoroiditis. This evidence concerns the gene CD4 and chorioretinitis.