Typically, intracellular bacteria are controlled after eliciting cell-mediated immune responses characterized by Th1 cytokines, IL12, and IFNγ, and in fact, humans with HGA develop very high levels of the Th1 cytokines IFNγ and IL12 during active infection (Dumler et al., 2000; Dumler et al., 2007). This evidence concerns the gene IFNG and infection.