Sarcocystis is a genus of protozoa. Species in this genus are parasites, the majority infecting mammals, and some infecting reptiles and birds. The life-cycle of a typical member of this genus involves two host species, a definitive host and an intermediate host. Often the definitive host is a predator and the intermediate host is its prey. The parasite reproduces sexually in the gut of the definitive host, is passed with the feces and ingested by the intermediate host. There it eventually enters muscle tissue. When the intermediate host is eaten by the definitive host, the cycle is completed. The definitive host usually does not show any symptoms of infection, but the intermediate host does.