These divergent roles are well illustrated in the context of malaria, a disease caused by infection with protozoan parasites of the genus Plasmodium. IFN-γ is a central cytokine in controlling Plasmodium infection in both the liver and blood stages of the parasite life cycle, but it can also exacerbate the severity of malarial disease depending on the temporal and spatial production of IFN-γ. The gene discussed is IFNG; the disease is malaria.