Criteria

World Health Organization (WHO): case definition (2009)[2]

The 1997 dengue case definition (below) is limited in terms of its complexity and applicability. This led to a new WHO classification where dengue severity is divided into dengue without warning signs, dengue with warning signs, and severe dengue. While WHO still support both case definitions, there is a move towards using the 2009 case definition due to its ease of use. One study found that the revised classification has a high potential for facilitating dengue case management and surveillance, and that it was more sensitive than the 1997 case definition for timely recognition of disease.[3] A meta-analysis found that the sensitivity was high (93%) for both the 1997 and 2009 definitions; however, specificity was low (29% for the 1997 definition and 31% for the 2009 definition).[95]

Dengue without warning signs:

  • Fever and two of the following:

    • Nausea/vomiting

    • Rash

    • Aches and pains

    • Leukopenia

    • 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 (e.g., ascites, pleural effusion)

    • Mucosal bleeding

    • Lethargy/restlessness

    • Liver enlargement >2 cm

    • Laboratory: increase in haematocrit concurrent with rapid decrease in platelet count.

  • Warning signs require strict observation and medical intervention.

Severe dengue:

  • Dengue with at least one of the following:

    • Severe plasma leakage leading to shock (dengue shock syndrome) or fluid accumulation with respiratory distress

    • Severe bleeding (as evaluated by a clinician)

    • Severe organ involvement (i.e., aspartate aminotransferase [AST] or alanine aminotransferase [ALT] 1000 or greater, impaired consciousness, organ failure).

World Health Organization: case definition (1997)[2]

The traditional classification is divided into dengue fever, dengue haemorrhagic fever, and dengue shock syndrome.

Dengue fever (DF):

  • Defined by the presence of fever and two or more of the following (but not meeting the case definition of dengue haemorrhagic fever):

    • Retro-orbital or ocular pain

    • Headache

    • Rash

    • Myalgia

    • Arthralgia

    • Leukopenia

    • Haemorrhagic manifestations (e.g., positive tourniquet test, petechiae, purpura/ecchymosis, epistaxis, gum bleeding, blood in vomit/urine/stool, vaginal bleeding).

Dengue haemorrhagic fever (DHF):

  • Fever lasting from 2 to 7 days

  • Evidence of haemorrhagic manifestation or a positive tourniquet test

  • Thrombocytopenia

  • Evidence of plasma leakage shown by haemoconcentration, pleural effusion, or ascites.

Dengue shock syndrome (DSS):

  • Has all the criteria of DHF plus circulatory failure as evidenced by:

    • Rapid and weak pulse and narrow pulse pressure, or

    • Age-specific hypotension and cold, clammy skin and restlessness.

World Health Organization: laboratory criteria for diagnosis of DSS/DHF

Laboratory criteria for the diagnosis of DSS/DHF include:[1][2]

  • Rapidly developing, severe thrombocytopenia (i.e., <100,000 cells/mm³ [<100 x 10⁹/L])

  • Decreased total WCC and neutrophils and changing neutrophil-to-lymphocyte ratio

  • Elevated haematocrit (i.e., 20% increase from baseline is objective evidence of plasma leakage)

  • Hypoalbuminaemia (i.e., serum albumin <35 g/L [3.5 g/dL] suggests plasma leakage)

  • Elevated liver function tests (i.e., AST:ALT >2).

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