Experimental Transmission of Toxoplasma gondii

Abstract

DESPITE the vast literature on the subject of Toxoplasma gondii, nothing is known of its natural method or methods of transmission apart from the fact that congenital transmission can occur in mammals. The possibility of faecal transmission has already been investigated together with many other possible modes of infection. Jacobs et al.¹ fed tissues infected with Toxoplasma to dogs. The faeces which were recovered at intervals afterwards were fed to mice but no infection resulted. The proliferative form of Toxoplasma, which sometimes can be found in faeces², and the cystic form which could “conceivably be liberated in faeces”³ both have insufficient tolerance to withstand the conditions prevailing in the external environment⁴. Consequently, little support can be given to the idea that these forms could survive long enough in faeces to effect transfer to another host. However, the possibility that free Toxoplasma in the intestine, liberated either from infected food or from intestinal lesions, might be capable of associating with intestinal nematodes and passing to the exterior within their ova seemed worthy of investigation. In order to test this hypothesis, the following preliminary experiment was carried out.