These results are coherent with previous observations with non-lethal strains of P. yoelii [17] and P. chabaudi [1], where CD4+T helper 1 cells, interferon-γ [18] and proinflamatory cytokine interleukin-12 [19] have been shown to be required for the control the parasitaemia within the first 7 to 14 days after infection. Here, CD4 is linked to infection.