Silva T, Jeewandara C, Gomes L, et al. - Vascular leak is a hallmark of severe dengue, and dengue mouse models exhibit high leukotriene levels, suggesting a role in disease pathogenesis. Researchers here examined their role in acute dengue, by determining the levels of urinary LTE4 and urinary histamine in patients with varying severity of acute dengue. Healthy individuals (n = 19), patients with dengue fever (DF = 72) and dengue haemorrhagic fever DHF (n = 48) were examined for urinary LTE4, histamine and creatinine using a quantitative ELISA. Patients who proceed to develop DHF exhibited significantly higher urinary LTE4 levels when compared with patients with DF during early illness (≤ 4 days) and during the critical phase, the levels continued to rise in patients who developed DHF during the course of illness. Patients with acute dengue had signficantly high urinary histamine levels although there was no difference between patients with DF and DHF and these did not associate with the viraemia. Interestingly, both patients with DF and DHF showed a marked diurnal variation in LTE4, histamine and the viral loads. Overall findings suggest a possible role of LTE4 in disease pathogenesis and as there are safe and effective cysteinyl leukotriene receptor blockers, it would be valuable to evaluate their efficacy in lowering dengue disease severity.