The protozoon parasite was named Toxoplasma gondii based on its morphology: “toxo” for arc- form; “plasma” for life and “gondii” for the host where it was first found. Although a single species has been described for the genus Toxoplasma, there are several clonal lineages that differ in their pathogenicity and virulence. The primary mechanism of the host's defence against protozoan infection is oxidative stress (OS). Oxidative stress is defined as an imbalance between the production of reactive oxygen species (ROS) and the antioxidant system of the organism.