Abstract: The present invention provides methods of determining whether a subject has a Dengue virus infection that is likely to develop into a life-threatening Dengue disease and methods of selecting a treatment regimen for a subject in need thereof who has been infected with a Dengue virus. The invention further provides a prognostic kit for distinguishing a subject who is likely to develop a mild Dengue disease from a subject who is likely to develop a life-threatening Dengue disease. The methods and kits of the invention can be used to differentiate DHF from DF and severe and non-severe forms of Dengue with high sensitivity and specificity.