Table 1.

Dengue severity stratification according to 1997 and 2009 World Health Organization (WHO) guidelines

1997 WHO classification			2009 WHO classification
Dengue fever	DHF (Grade 1 and 2)	DSS (Grade 3 and 4)	DWoWS	DWWS	SD
Acute febrile illness with ≥ 2 of the following symptoms:  Headache  Retro-orbital pain  Myalgia  Arthralgia  Rash Haemorrhage manifestations  Leukopenia	Following must be all present:  Fever or history of fever  Haemorrhage tendencies (as manifested by a positive tourniquet test, petechiae/purpura/ecchymoses, mucosal bleeding)  Thrombocytopenia  Plasma leakage (a rise in the haematocrit, pleural effusion, ascites)	All four criteria of DHF plus evidence of circulatory failure evidenced by:  Rapid and weak pulse  Narrow pulse pressure (< 20 mm Hg)  Hypotension  Cold clammy skin and restlessness	Fever and two of the following symptoms:  Nausea or vomiting  Rash  Bodyaches  Positive tourniquet test  Leukopenia	Similar features of DWoWS with the following warning signs:  Abdominal pain  Persistent vomiting  Lethargy or restlessness  Liver enlargement  Increase in HCT and decrease in platelet count	Patients with any of the following features:  Severe plasma leakage leading to Shock, fluid accumulation with respiratory distress  Severe bleeding  Severe organ impairment

DHF dengue haemorrhagic fever, DSS dengue shock syndrome, DWoWS dengue without warning signs, DWWS dengue with warning signs, SD severe dengue, HCT haematocrit

*Case definition of severe dengue used in the meta-analysis is shaded in grey