An infected leech feeding on a reptile or amphibian injects sporozoites into the bloodstream. These enter erythrocytes and become trophozoites. Erythrocytes with large trophozoites lodge in the capillaries of the bone marrow and become macroschizonts. About 14 merozoites are produced, which enter the bloodstream and infect new erythrocytes. There the parasite develops into microschizonts that contain about 6 merozoites. These merozoites infect new erythrocytes and beome micro or macrogametocytes. They remain in this stage until ingested by another feeding leech. In the intestine of the leech, gametes fuse and form a zygote that develops into an oocyst. The oocyst hatches in the leech's intestine and sporozoites migrate through the intestinal wall and into the circulatory system. Many that end up in the proboscis of the leech are injected into the next host that the leech feed on.