Fewer granulocytes move out from the bone marrow and in a separate action induces the rodent's own heme oxygenase 1 (HO-1).

Although HO-1 induction is a tolerance response by the host to malaria – preventing damage caused by the host's own immune response – the reduced reactive oxygen species production takes away a weapon vital to fighting some unrelated microbes.

Cunnington et al. 2012 find mice tolerating P. yoelii 17XNL do not clear coinfections with other pathogens as easily as they normally would.

[1] It is used in the laboratory to infect mice, as a model of human malaria, particularly with respect to the immune response.

Comparison of these two strains can be used to deduce which factors may contribute to more serious malaria infections in humans.