Sunday, June 6, 2021

Dengue classification

WHO 1997 classification :

Dengue fever —  >2 of the following 


Retro-orbital or ocular pain

Myalgia and/or bone pain



Hemorrhagic manifestations (eg, positive tourniquet test, petechiae, purpura/ecchymosis, epistaxis, gum bleeding, blood in emesis, urine, or stool, or vaginal bleeding)


Dengue hemorrhagic fever — The cardinal feature of DHF is plasma leakage due to increased vascular permeability as evidenced by hemoconcentration (≥20 percent rise in hematocrit above baseline). In the setting of DHF, the presence of intense abdominal pain, persistent vomiting, and marked restlessness or lethargy, especially coinciding with defervescence, should alert the clinician to possible impending DSS.

According to the guidelines, a DHF diagnosis requires all of the following be present:

Fever or history of acute fever lasting 2 to 7 days, occasionally biphasic 

Hemorrhagic tendencies evidenced by at least one of the following:

A positive tourniquet test – The tourniquet test is performed by inflating a blood pressure cuff on the upper arm to a point midway between the systolic and diastolic pressures for 5 minutes. A test is considered positive when 10 or more petechiae per 2.5 cm (1 inch) square are observed. The test may be negative or mildly positive during the phase of profound shock. It usually becomes positive, sometimes strongly positive, if the test is conducted after recovery from shock.

Petechiae, ecchymoses, or purpura.

Bleeding from the mucosa, gastrointestinal tract, injection sites, or other locations.

Hematemesis or melena.

Thrombocytopenia (100,000 cells per mm3 or less) –  In healthy individuals, 4 to 10 platelets per oil-immersion field (100x; the average of the readings from 10 oil-immersion fields is recommended) indicates an adequate platelet count. An average of 3 platelets per oil-immersion field is considered low (ie, 100,000 per mm3).

Evidence of plasma leakage due to increased vascular permeability manifested by at least one of the following:

A rise in the hematocrit equal to or greater than 20 percent above average for age, sex, and population.

A drop in the hematocrit following volume-replacement treatment equal to or greater than 20 percent of baseline.

Signs of plasma leakage such as pleural effusion, ascites, and hypoproteinemia.

Dengue shock syndrome — DSS consists of DHF with marked plasma leakage that leads to circulatory collapse (shock) as evidenced by narrowing pulse pressure or hypotension.

Rapid and weak pulse.

Narrow pulse pressure ( ≤20 mmHg) or manifested by: observed early in the course of shock.

Hypotension for age – observed later or in patients who experience severe bleeding.

Hypotension is defined to be a 

  • SBP 80 mmHg  for those < 5 years of age 
  • SBP 90 mmHg  for those equal to or > 5 years of age.

Cold, clammy skin and restlessness.

WHO 2009 classification — 

Dengue without warning signs —>2 of the following 



Headache, eye pain, muscle ache, or joint pain


Positive tourniquet test

Dengue with warning signs —  any of the following 

Abdominal pain or tenderness

Persistent vomiting

Clinical fluid accumulation (ascites, pleural effusion)

Mucosal bleeding

Lethargy or restlessness

Hepatomegaly >2 cm

Increase in hematocrit concurrent with rapid decrease in platelet count

Severe dengue —at least one of the following :

Severe plasma leakage leading to:


Fluid accumulation with respiratory distress

Severe bleeding

Severe organ involvement:

Aspartate aminotransferase (AST) or alanine aminotransferase (ALT) ≥1000 units/L

Impaired consciousness

Organ failure

  1. Sudden high-grade fever (≥38.5°C) Children have high fever but are generally less symptomatic than adults during the febrile phase. The febrile phase lasts for three to seven days, after which most patients recover without complications. 
  2. What is Biphasic fever ("saddleback") ?  - 1st febrile phase remits & recurs approx 1 to 2 days later & this 2nd febrile phase lasts 1 to 2 days.
  3. Serum aspartate transaminase (AST) levels are frequently elevated; the elevations are usually modest (2 to 5 times the upper limit of normal values), but marked elevations (5 to 15 times the upper limit of normal) occasionally occur.
  4. Between days 3 and 7 of the illness, you must watch for signs of vascular leakage. Corresponding clinical manifestations may include persistent vomiting, increasingly severe abdominal pain, tender hepatomegaly, development of pleural effusions and/or ascites, mucosal bleeding, and lethargy or restlessness; laboratory findings may include a high or increasing hematocrit level (≥20 percent from baseline) concurrent with a rapid decrease in the platelet count
  5. The vast majority of DENV infections that progress to a critical phase result from secondary infections more than 18 months after the first infection.The critical phase lasts for 24 to 48 hours.
Thank you! 🫀🩺

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