For instance, while IFN-γ-deficient mice are highly susceptible to T. brucei or T. congolense infection and fail to control the first wave of parasitemia (85, 87), neutralization of IFN-γ by antibody treatment during T. congolense infection is associated with enhanced resistance (lower parasitemia and prolonged survival) of the highly susceptible mice (79). This evidence concerns the gene IFNG and parasitic infectious disease.