Yacoub S, et al. - A prospective observational study in 2 Vietnamese hospitals is performed to determine the association of endothelial nitric oxide pathways with dengue severity. This study revealed that impaired endothelial function is associated with dengue plasma leakage severity. Researchers identify that endothelial dysfunction occurs early in dengue illness and correlates with hypoargininemia and high arginase-1 levels.