The effect of treatment on Plasmodium burden by co-infection status with (a) Plasmodium only, (b) Plasmodium and Leucocytozoon, (c) Plasmodium and Haemoproteus, and (d) Plasmodium, Haemoproteus, and Leucocytozoon. Letters (a, b) represent significant differences (p < 0.05) among treatments within the same panel. In the absence of Haemoproteus, (a,b), high-dose corticosterone causes an increase in Plasmodium burden, but the effect disappears with Haemoproteus co-infection (c,d).