CD40LG and dengue disease: NS1 is a conserved glycoprotein that is secreted from infected cells as a hexamer and can be measured to detect dengue infection.15 Unlike IgM and IgG, it is present during the acute viraemic phase of infection,37 consistent with its postulated role in viral replication.38 Its early presence, specificity to dengue and abundance in sera make it useful for early diagnosis, and the need for only a single sample allows it to inform clinical management.