Dengue hemorrhagic fever (DHF) is a severe, potentially deadly infection spread by mosquitos. CDC scientists have identified vitronectin as an important biomarker of DHF. They have shown vitronectin is significantly reduced in DHF and severe dengue infections when compared to dengue non-hemorrhagic fever patients. Presently, DHF is established by assessing antibody concentrations and other rule-of-thumb criteria, but often these assays can be difficult to interpret and lead to false conclusions. Establishing vitronectin levels provides a specific, novel biomarker for DHF, leading to increased accuracy in clinical diagnoses and improved patient outcomes.