What are the diagnosis, treatment, and monitoring protocols for dengue?

Diagnosis, Treatment, and Monitoring of Dengue

Diagnostic Approach

For symptomatic patients presenting within 7 days of symptom onset, perform nucleic acid amplification testing (NAAT/PCR) on serum; for those presenting after 7 days or with negative NAAT results, perform IgM capture ELISA. 1

Timing-Based Testing Strategy

• Days 1-7 of illness: Dengue viral RNA is detectable in serum from approximately 2 days before symptom onset through the first week of illness, making NAAT/PCR the preferred diagnostic method during this window 1
• After day 7 or negative NAAT: IgM antibodies typically develop during the first week of illness and persist for months, making IgM capture ELISA the appropriate test for later presentations 1, 2
• NAAT can be performed on serum, plasma, whole blood, cerebrospinal fluid, or urine, though serum remains the standard specimen 3

Clinical Criteria for Testing

• Test patients with fever plus at least one of the following: frontal headache, retro-orbital pain, myalgias, arthralgias, rash, nausea, vomiting, leukopenia, or dengue warning signs 3, 1
• The incubation period is 4-8 days after mosquito exposure, which helps establish epidemiologic risk 1
• Consider co-infection with Zika virus in endemic areas, as both are transmitted by Aedes mosquitoes and share overlapping clinical features 3, 2

Special Population: Pregnant Women

• Test all pregnant women with symptoms for both dengue and Zika by NAAT, regardless of local outbreak patterns, due to distinct but serious complications from each virus 3, 2
• Collect serum and urine as soon as possible within 12 weeks of symptom onset for simultaneous testing 1
• Dengue increases risk for maternal hemorrhage, preeclampsia, eclampsia, and peripartum complications, while Zika causes fetal microcephaly and congenital abnormalities 3, 2

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Clinical Presentation and Risk Stratification

Characteristic Symptoms

• Fever is present in nearly all cases, accompanied by frontal headache, retro-orbital pain, myalgias, arthralgias, and often a maculopapular rash 1, 4
• The disease follows a triphasic course: febrile phase (days 1-3), critical phase (days 4-7 when plasma leakage occurs), and recovery phase (after day 7) 4

Warning Signs Requiring Daily Monitoring

Monitor daily for these warning signs that predict progression to severe dengue: 1, 5

• Persistent vomiting preventing adequate oral intake
• Severe abdominal pain or tenderness
• Clinical fluid accumulation (pleural effusion, ascites)
• Mucosal bleeding (epistaxis, gingival bleeding, hematemesis)
• Lethargy or restlessness
• Rising hematocrit with rapidly falling platelet count

Severe Dengue Definitions

• Dengue hemorrhagic fever (DHF): Thrombocytopenia ≤100,000/mm³, evidence of plasma leakage (hemoconcentration, pleural effusion, ascites), and hemorrhagic manifestations 5
• Dengue shock syndrome (DSS): All DHF criteria plus hypotension or narrow pulse pressure (<20 mmHg) 5
• Severe dengue carries 1-5% mortality but is rare, occurring in less than 10% of cases 4

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Laboratory Monitoring

Daily Complete Blood Count

Perform daily CBC to monitor three critical parameters: 1, 5

• Platelet count: Thrombocytopenia ≤100,000/mm³ defines DHF and indicates increased bleeding risk
• Hematocrit: An increase ≥20% from baseline indicates plasma leakage and hemoconcentration
• White blood cell count: Leukopenia is frequent during the febrile phase 2

Additional Laboratory Surveillance

• Monitor liver enzymes (AST/ALT), as elevated transaminases predict poor outcomes and fulminant hepatitis occurs in 69% of nonsurvivors 6
• Check coagulation parameters (PT/INR, PTT), as peak INR and PTT are independent risk factors for mortality 6
• Sequential Organ Failure Assessment (SOFA) score is the strongest predictor of survival in severe cases 6

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Treatment

Fundamental Principle

Dengue treatment is purely symptomatic with rigorous fluid management, as no specific antiviral therapy exists. 1

Uncomplicated Dengue (No Shock)

• Ensure adequate oral hydration with oral rehydration solutions, targeting >2,500 mL daily for adults 1, 5
• Use acetaminophen/paracetamol at standard doses for fever and pain control 2, 5
• Never use aspirin or NSAIDs due to increased bleeding risk from antiplatelet effects and potential for hemorrhagic complications 2, 5

Dengue Shock Syndrome Management

For patients with hypotension or narrow pulse pressure (<20 mmHg): 1, 5

• Administer an initial bolus of 20 mL/kg isotonic crystalloid (normal saline or Ringer's lactate) over 5-10 minutes
• Reassess immediately after the bolus for improvement in blood pressure, pulse pressure, capillary refill, and mental status
• Repeat 20 mL/kg boluses if shock persists after initial resuscitation
• Consider colloid solutions (albumin, dextran) for severe shock with pulse pressure <10 mmHg when crystalloids fail 5

Management of Hemorrhagic Complications

• Transfuse packed red blood cells for significant bleeding with hemodynamic compromise 5
• Platelet transfusion may be necessary for severe thrombocytopenia with active bleeding, though prophylactic transfusion is not routinely recommended 5
• For persistent hypotension despite adequate fluid resuscitation, consider vasopressors (dopamine or epinephrine) 5

Special Populations

• Pregnant women: Acetaminophen remains the safest analgesic option; avoid all NSAIDs and aspirin 5
• Children: Calculate acetaminophen dosing carefully based on weight (10-15 mg/kg every 4-6 hours) 5

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Monitoring During Hospitalization

Critical Phase Monitoring (Days 4-7)

• Monitor vital signs every 1-4 hours depending on severity: blood pressure, pulse pressure, heart rate, capillary refill time 1
• Measure urine output hourly in severe cases, targeting >0.5 mL/kg/hour in adults 5
• Perform daily hematocrit measurements to detect plasma leakage early 1
• Assess for clinical fluid accumulation through chest auscultation and abdominal examination 1

Common Pitfalls to Avoid

• Do not delay fluid resuscitation while awaiting laboratory confirmation in patients with clinical shock 5
• Do not change management based solely on persistent fever without clinical deterioration or new findings 5
• Avoid over-aggressive fluid administration in the recovery phase, as this can lead to pulmonary edema when plasma reabsorption occurs 5
• Never administer aspirin or NSAIDs when dengue cannot be excluded, even for mild symptoms 5

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Discharge Criteria

Patients can be safely discharged when ALL of the following criteria are met: 1, 5

• Afebrile for ≥48 hours without antipyretics
• Resolution or significant improvement of symptoms (including gastrointestinal symptoms, pain)
• Stable hemodynamic parameters for ≥24 hours without fluid support (normal blood pressure, heart rate, capillary refill)
• Adequate oral intake maintained
• Normal urine output (>0.5 mL/kg/hour in adults)
• Laboratory parameters returning toward normal ranges (rising platelets, stable hematocrit)

Post-Discharge Instructions

• Monitor and record temperature twice daily for 7 days after discharge 5
• Return immediately if fever recurs (≥38°C on two consecutive readings) or any warning signs develop 5
• Schedule follow-up within 48-72 hours to reassess clinical status and repeat CBC 5

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Epidemiology and Prevention

• Aedes mosquitoes (primarily Aedes aegypti, also Aedes albopictus) are the vectors and bite predominantly during daylight hours 1, 4
• Transmission occurs in tropical and subtropical regions, with over 100 million symptomatic cases annually worldwide 4
• Prevention focuses on mosquito bite avoidance (repellents, protective clothing, bed nets) and vector control 4
• Dengue is a nationally notifiable condition; report suspected cases to local health departments to facilitate outbreak response 3