Course of Plasmodium yoelii 17X blood stage infection in male BALB/cByJ mice. Animals (n = 5) were infected by intraperitoneal injection with 1x105P. yoelii 17X infected RBCs. Parasitaemia and percent reticulocytes were monitored in thin tail-blood smears stained with Giemsa. Average percent parasitaemia (red) and reticulocytes (blue) at various days post-infection are shown.