IFNG and infection: The study from Kerman, central Iran demonstrated that symptomatic giardiasis was characterized by significantly elevated serum levels of the TH1 cytokine IFN-γ compared to healthy controls, while asymptomatic human subjects and healthy controls had comparable levels of serum IFN-γ, and that Giardia genotype AI infection was associated with significantly elevated levels of serum IFN-γ and IL-10, but not IL-5, compared to healthy controls [21].