Assessment and management of dengue

Abstract

Terminology and definitions The classifications in box 1 replaced the 1997 WHO classifications of “dengue fever,” “dengue haemorrhagic fever,” and “dengue shock syndrome,” but these older terms are still used in some regions, including by some WHO regional offices (such as the WHO South-East Asia Regional office).15 Box 1 Classifications of dengue WHO (2009)13 Case definition—Fever up to 40°C lasting at least two days; plus at least two of the following: rash, nausea or vomiting, aches, positive tourniquet test for capillary fragility,* leucopenia, the presence of any dengue warning sign (see box 2)21113 Symptomatic dengue—Categorised as dengue fever without warning signs, dengue fever with warning signs, or severe dengue13 Severe dengue—One or more of: compensated or hypotensive shock,† respiratory distress, severe bleeding, severe organ impairment2 Group A/B1/B2/C classification—Used for management (see table 2): A: WHO (2009)13 and CDC Yellow Book on traveller’s health (2024)14 Disease course terminology—Febrile, critical, and recovery phases (largely correlating with the classifications “dengue fever without warning signs,” “dengue fever with warning signs,” and “severe dengue”) * The tourniquet test entails inflating a sphygmomanometer cuff on the arm to a point midway between the patient’s systolic and diastolic blood pressures and maintaining it for five minutes: in a positive result, ≥10 petechiae per square inch will appear in the cubital fossa 1-2 minutes after deflating the cuff11 † Maintained systolic blood pressure (>90 mm Hg) with pulse pressure <20 mm Hg indicates compensated shock, while systolic blood pressure <90 mm Hg indicates hypotensive shock13 In this article, we mainly use the terms “febrile, critical, and recovery phase” and, within that, “warning signs” and “severe dengue.” The positive predictive values of individual warning signs for progression to severe dengue, range from 9% (for persistent vomiting) to 58% (fluid accumulation), but negative predictive values are higher (greater than 95% for each of the individual warning signs).38 Unless organ support is needed (inotropic support, mechanical ventilation, and/or dialysis), the critical phase usually lasts 2-3 days.213 Box 2 Dengue warning signs and risk factors for severe disease91317 Warning signs Abdominal pain or tenderness Persistent vomiting (≥3 episodes in 1 hour, or 4 episodes in 6 hours) Fluid accumulation from plasma leakage (such as ascites, pleural effusion, oedematous gall bladder wall, peripheral oedema) Mucosal bleeding (usually gum or nasal bleeding, sometimes vaginal or gastrointestinal bleeds or haematuria) Lethargy Restlessness Liver enlargement >2 cm Laboratory: increase in haematocrit, concurrent with rapid decrease in platelet count Risk factors for severe disease Pregnancy1232 Infants <1 year old33 Adults >65 years old34 Underlying health conditions (diabetes, asthma, hypertension, chronic kidney disease, heart failure)3536 Obesity37 Also consider people who reside far from hospitals, live alone, or experience extreme poverty (who may not receive adequate home care and be unable to attend follow-up) Examination21321: Monitor (every 2-4 hours) for the development of severe dengue by assessing airway, breathing, and circulation (including blood pressure, and urine output), and consciousness. Narrow pulse pressure occurs if systolic blood pressure decreases and diastolic increases Cool, clammy extremities might indicate hypotensive or compensated shock Assess for bleeding (mucosa, orifices, skin) that may occur with severe thrombocytopenia or coagulopathy Consider severe bleeding if haematocrit decreases and the patient remains haemodynamically unstable (cool clammy extremities, low blood pressure, decreased urine output) despite intravenous fluids resuscitation Assess for signs of organ impairment (such as hepatic failure, encephalopathy, cardiomyopathy).