Greek: toxon = bent, crescentic structure; plasma = structure, mass; the species name was given in 1907 by the two French Army physicians Nicolle and Manceaux, since the bent half-moon-shaped trophozoite stage of this parasite was first discovered in the rodent species Ctenodactylus gundi in North Africa.

This parasite is distributed worldwide and has been described in practically all species of mammals with high infection rates. Thus, T. gondii is probably the most common parasite on earth. About 60–80 % of humans aged more than 60 years are infected and thus bear antibodies. In younger humans, the infection rates increase with increasing age. In immunocompromised people, T. gondii turned out to be the “killer no. 3” after Pneumocystis jiroveci and Cryptosporidium species. Thus, it is regarded as “opportunistic parasite.”