Other studies using the P. chabaudi murine model of infection that induces low chronic blood-parasitemia rebounds over 1-3 months post infection (13, 38), have also reported CD8+ T cells, which express high cell-surface PD-1, to be essential in mediating effective blood stage parasite clearance during the chronic rebound phase and PD-1 blockade (13). Here, PDCD1 is linked to parasitic infectious disease.