Definition and epidemiology
Dengue is a mosquito-borne (Aedes aegypti) flaviviral infection caused by four serotypes (DENV 1–4). It is hyperendemic across India with seasonal monsoon and post-monsoon peaks. Infection with one serotype confers lifelong homotypic immunity but only transient heterotypic protection; secondary infection with a different serotype carries a higher risk of severe disease through antibody-dependent enhancement. Children, particularly infants and the obese, are an important at-risk group for plasma leakage and shock.
Clinical features
Classic illness follows three phases:
- Febrile phase (days 1–3): abrupt high fever, headache, retro-orbital pain, myalgia, facial flushing, and a positive tourniquet test. Young children may present with undifferentiated fever.
- Critical phase (around defervescence, days 3–7): the period of maximal plasma leakage lasting ~24–48 h. This is when warning signs and shock emerge — often as the fever settles, which can falsely reassure.
- Recovery phase: reabsorption of extravasated fluid, bradycardia, and a confluent “isles of white in a sea of red” convalescent rash; watch for fluid overload here.
Diagnostic criteria
WHO 2009 classifies cases as dengue without warning signs, dengue with warning signs, and severe dengue. Probable dengue = fever plus ≥2 of nausea/vomiting, rash, aches, leukopenia, positive tourniquet test, or any warning sign, in an endemic setting. The seven warning signs are: abdominal pain/tenderness, persistent vomiting, clinical fluid accumulation (ascites/effusion), mucosal bleeding, lethargy or restlessness, hepatomegaly >2 cm, and a rising haematocrit with rapid fall in platelets. Severe dengue is defined by severe plasma leakage (shock or respiratory distress from fluid accumulation), severe bleeding, or severe organ impairment (e.g. AST/ALT ≥1000, impaired consciousness, myocarditis). Confirmation: NS1 antigen (highest yield days 1–5), and IgM seroconversion from ~day 5; RT-PCR where available.
See the full criteria: Dengue
Red flags
- Any WHO warning sign — these mandate admission and close monitoring
- Narrowing pulse pressure (≤20 mmHg), tachycardia with cool peripheries, delayed capillary refill (compensated shock in children precedes hypotension)
- Rapidly rising haematocrit with falling platelets
- Significant bleeding, altered sensorium, or signs of organ involvement
Management overview
There is no specific antiviral therapy; management is supportive and centres on judicious fluid therapy titrated to the critical phase. Use paracetamol for fever and avoid NSAIDs and aspirin (bleeding/Reye risk). Ambulatory patients with no warning signs are managed with oral fluids and daily review including serial platelet/haematocrit. Warning signs or severe dengue require admission and isotonic crystalloid (0.9% saline or Ringer’s lactate), starting at maintenance-plus with frequent reassessment of haematocrit, urine output, and haemodynamics; boluses are reserved for shock and weaned as leakage resolves to avoid fluid overload. Platelet transfusion is not indicated for thrombocytopenia alone — only for significant bleeding or per local thresholds. Anticipate the recovery-phase risk of pulmonary oedema as extravasated fluid returns.
References
- WHO. Dengue: Guidelines for Diagnosis, Treatment, Prevention and Control. 2009.
- WHO/SEARO comprehensive guidelines, revised 2011.
- NVBDCP India national guidelines for clinical management of dengue, 2014.
Decision support for qualified clinicians only — verify against current primary guidelines and your clinical judgement.