That the protozoan, Toxoplasma gondii, can pass the placental barrier to produce devastating cerebral and ocular infections of the fetus while the mother remains completely asymptomatic, is a well-recognized fact. But how does the mother acquire her infection? And what is the source of infection in acquired Toxoplasma chorioretinitis in adults? Ever since Wilder1 demonstrated that toxoplasmosis is an important cause of acquired chorioretinitis, the natural reservoir and mode of transmission of the parasite to man have remained a mystery.
Animals can be infected by the oral route and since the proliferative form of Toxoplasma gondii can be excreted in the feces, it was natural to suspect fecal transmission.2 On the other hand, neither the proliferative nor the cystic forms of this parasite are sufficiently hardy to survive the external environment, and simple fecal contamination of food seemed unlikely.
While carnivorous animals may acquire toxoplasmosis by eating the
Z. L. Toxoplasma gondii From Toxocara cati!. Arch Ophthalmol. 1966;76(2):159-160. doi:10.1001/archopht.1966.03850010161001