The Toxoplasma gondii life cycle and pathways for infection

The only source for the production of T. gondii oocysts (sporozoites) is the feline intestinal tract. Acquired disease in humans occurs by direct ingestion of oocysts from contaminated sources (soil, cat litter, garden vegetables) or by ingestion of tissue cysts (bradyzoites) present in undercooked tissues from infected animals. Fetal infection most commonly occurs after acute maternal infection in pregnancy, but it can also occur after reactivation of latent infection in immunocompromised women. Pathways leading to human disease are indicated by solid arrows, and pathways leading to feline infection are indicated by broken arrows.