Variations in the cytokine production and high Th1 (TNF-α) and Th2 (IL-4, IL-5 and IL-10) profile levels in the co-infected group therefore suggest that cytokines exhibit marked increases in their plasma concentrations when individuals are infected with P. vivax, with a shifting pattern inchanges associated with malaria and intestinal parasite co-infection. The gene discussed is IL4; the disease is malaria.