The production of NO and pro-inflammatory cytokines like IL-1β, TNF-α and IFN-γ is critical for destroying intracellular microorganisms, included the protozoan parasite T. cruzi. However, in the case of Chagas disease, even though the parasite ́s replication is controlled through pro-inflammatory cytokines and microbicidal mediators released by cells of the innate immunity and the subsequent lymphocyte subsets activated during the adaptive immunity response, not all parasites are killed and the infection persists in the host for life. This evidence concerns the gene IFNG and infection.