Therefore, elevation of IFN-γ production upon PvMSP1P-19 stimulation could be explained by production of effector Th1 cells or memory cells specific to PvMSP1P-19 in malaria-recovered human populations, and that effector cells could be re-stimulated to produce IFN-γ, indicating a boosting of cellular immunity in individuals following natural exposure to the P. vivax parasite. Here, IFNG is linked to malaria.