Some studies have reported the upregulation of serum IL-4 in CHIKV [13, 14] and DENV-infected patients [7], as well as increased number of IL-4 expressing PBMC of paediatric dengue haemorrhagic fever [36], although the differential expression of IL-4 by DENV-2 (i.e. markedly upregulated in DENV-2, but not/only slightly in other serotypes) has not been reported before. The gene discussed is IL4; the disease is Dengue hemorrhagic fever.