Co-infection with low density P. berghei and increased S. japonicum cercariae significantly increased the levels of IL-4, IL-5, IL-13, TGF-β and Tregs, but significantly decreased the levels of IFN-γ and the percentage of CD4+ T cells and CD8+ T cells in the spleen and CD8+ T cell infiltration in the brain. This evidence concerns the gene CD4 and coinfection.