Fig. 1.

Life cycle of T. gondii. Parasites are shed by definitive feline hosts in the form of oocysts, which may then be ingested by intermediate hosts. Transmission back to definitive hosts may occur by ingestion of infected intermediate host tissue containing parasites in tissue cysts. The sylvatic cycle includes many definitive wild feline host species and varied mammalian and avian intermediate host species, whereas the domestic cycle includes the domestic cat as a definitive host and the house mouse as an important intermediate host. Transmission may also occur through scavenging among the intermediate hosts.