IL6 and Dengue hemorrhagic fever: Accordingly, it has been reported that high levels of IFN-γ, IL-6, and IL-8 have been found in dengue-infected patients, in whom significant levels of IL-6 and IL-8 were linked to dengue hemorrhagic fever (DHF), and that the mean levels of these three cytokines were lower in primary dengue infection cases than in secondary ones [50,51,52].