Several cytokines such as IFN-γ, TNF-α, IL-4, IL-10, IP-10 and VCAM-1 have been shown to be elevated in patients with SD [29–31] while in other studies, the same cytokines such as IFN-γ and TNF-α showed no difference in levels between patients with mild dengue fever and severe dengue [27, 32]. This evidence concerns the gene IL4 and dengue disease.