This article focuses on the positive association between T. gondii and mood disorders and analyzes the possible mechanisms of this association, with the immune system serving as a possible bridge between the two T. gondii infection alters the peripheral and central immune status, with an increase in peripheral CD4+ T cells and their recruitment into the brain parenchyma, accompanied by the development and transfer of inflammation (Ploix et al., 2011; Severance et al., 2016), or directly into the CNS to promote microglia activation (Courret et al., 2006; Matta et al., 2021) (Figure 1). This evidence concerns the gene CD4 and mood disorder.