Clinical Description For Case Definitions
In 1997 the dengue case definition was limitated in terms of its complexity and applicability. This recognition of the limitations led to a multicenter study in seven countries in Asia and Latin America and a new case definition emerged from this study. The new WHO classification for dengue severity is divided into Dengue without Warning Signs, Dengue with Warning Signs, and Severe Dengue.
2009 New Dengue Case Definitions
Dengue without Warning Signs
Fever and two of the following:
- Nausea, vomiting
- Aches and pains
- Positive tourniquet test
Dengue with Warning Signs**
Dengue as defined above with any of the following:
- Abdominal pain or tenderness
- Persistent vomiting
- Clinical fluid accumulation (ascites, pleural effusion)
- Mucosal bleeding
- Lethargy, restlessness
- Liver enlargement >2 cm
- Laboratory: increase in HCT concurrent with rapid decrease in platelet count
**requires strict observation and medical intervention
Dengue with at least one of the following criteria:
- Severe Plasma Leakage leading to:
– Shock (DSS)
– Fluid accumulation with respiratory distress
- Severe Bleeding as evaluated by clinician
- Severe organ involvement
– Liver: AST or ALT ≥ 1000
– CNS: impaired consciousness
– Failure of heart and other organs
The traditional WHO classification is defined as follows: Dengue Fever (DF), Dengue Hemorrhagic Fever (DHF), and Dengue Shock Syndrome (DSS).
1997 Dengue Case Definitions
Dengue fever is most commonly an acute febrile illness defined by the presence of fever and two or more of the following, retro-orbital or ocular pain, headache, rash, myalgia, arthralgia, leukopenia, or hemorrhagic manifestations (e.g., positive tourniquet test, petechiae; purpura/ecchymosis; epistaxis; gum bleeding; blood in vomitus, urine, or stool; or vaginal bleeding) but not meeting the case definition of dengue hemorrhagic fever. Anorexia, nausea, abdominal pain, and persistent vomiting may also occur but are not case-defining criteria for DF.
Dengue hemorrhagic fever is characterized by all of the following:
- Fever lasting from 2-7 days
- Evidence of hemorrhagic manifestation or a positive tourniquet test
- Thrombocytopenia (≤100,000 cells per mm3)
- Evidence of plasma leakage shown by hemoconcentration (an increase in hematocrit ≥20% above average for age or a decrease in hematocrit ≥20% of baseline following fluid replacement therapy), or pleural effusion, or ascites or hypoproteinemia.
Dengue shock syndrome has all of criteria for DHF plus circulatory failure as evidenced by:
- Rapid and weak pulse and narrow pulse pressure (<20mm Hg), or
- Age-specific hypotension and cold, clammy skin and restlessness.