Previous studies have shown that susceptibility to T. congolense infection in mice is associated with the production of high levels of proinflammatory cytokines (including TNF-α, IL-6, IL-12, and IFN-γ) by spleen cells from infected mice leading to increased serum levels of the cytokines, systemic inflammatory response syndrome (SIRS) and death [14–17]. Here, IL6 is linked to systemic inflammatory response syndrome.