As previously reported [24] [25] [26] , we also were often unable to characterize the severe disease forms based on WHO criteria [3]. In Nicaragua, Harris et al. [24, 27] described four key severe clinical manifestations associated with dengue -shock, plasma leakage, marked thrombocytopenia or internal haemorrhage -that do not fit DHF/DSS classification as single parameters. According to these criteria, we considered: