IL6 and systemic inflammatory response syndrome: Death of infected BALB/c mice is usually related to immune hyper-activation of cells, particularly macrophages and T cells, leading to massive production of pro-inflammatory cytokines (including IFN-γ, IL-1, IL-6, IL-12 and TNF-α and systemic inflammatory response syndrome (SIRS) [9] In contrast, C57BL/6 mice are considered relatively resistant to T. congolense infection because they can control several waves of parasitemia and survive for over 100 days [9].