This gradual reduction in blood stage parasitemia between days 9 to 13 post-sporozoite infection is likely due to clearance of human red blood cells and is consistent with previous33 and more recent work on a similar Fah−/−/Rag2−/−/Il2rg−/− (FRG) HuHep infection model.34 The gene discussed is IL2RG; the disease is infection.