For these reasons, a study has been performed to evaluate the diagnostic value of a positive single specimen test result revealed by a standard ELISA-kit (PanBio-IgM- and IgG-ELISA) in ill travellers returning from dengue endemic countries in different parts of the world and how to increase its predictive value with the help of simple clinical and haematological features. The gene discussed is CD40LG; the disease is dengue disease.