What are the diagnostic tests and management strategies for dengue fever?

Dengue Fever Diagnostic Testing and Management

For patients with suspected dengue fever, diagnosis should be made using RT-PCR for dengue virus RNA in serum or NS1 antigen detection during the acute phase (≤7 days after symptom onset), and IgM antibody testing during the convalescent phase (>7 days after symptom onset). 1

Clinical Presentation and Suspicion

Dengue fever should be suspected in patients presenting with:

• Fever accompanied by at least one of the following:
  • Headache
  • Retro-orbital pain
  • Myalgia
  • Arthralgia
  • Rash
  • Nausea/vomiting
  • Leukopenia
• Recent travel to or residence in endemic areas 1

Diagnostic Testing Algorithm

For specimens collected ≤7 days after symptom onset:

• Perform dengue virus nucleic acid amplification test (NAAT) on serum 2
• NS1 antigen detection can also be used during this acute phase 1
• If NAAT is negative, proceed to IgM antibody testing 2

For specimens collected >7 days after symptom onset:

• Perform dengue virus IgM antibody testing 2
• If IgM positive, confirm with plaque reduction neutralization test (PRNT) when clinically indicated 2

Interpretation of results:

• Positive dengue NAAT: Acute dengue virus infection
• Positive dengue IgM with dengue PRNT ≥10 and Zika PRNT <10: Recent dengue virus infection
• Positive IgM with positive IgG: Suggests secondary dengue infection (higher risk for severe disease) 1

Laboratory Findings Supporting Diagnosis

Look for:

• Thrombocytopenia (platelet count <100,000/mm³)
• Leukopenia
• Elevated hematocrit (indicating hemoconcentration)
• Elevated liver enzymes 1

Management Based on Disease Classification

Dengue without warning signs (outpatient management):

• Oral hydration
• Acetaminophen/paracetamol for fever and pain
• Daily follow-up until fever resolves
• Avoid NSAIDs and aspirin due to bleeding risk 1

Dengue with warning signs (consider hospitalization):

• Warning signs include:
  • Abdominal pain/tenderness
  • Persistent vomiting
  • Clinical fluid accumulation
  • Mucosal bleeding
  • Lethargy/restlessness
  • Liver enlargement
  • Increasing hematocrit with decreasing platelets 1
• Initiate IV fluid therapy with crystalloids (5-10 ml/kg/hour)
• Monitor vital signs, fluid balance, and laboratory parameters 1

Severe dengue (requires hospitalization):

• Aggressive fluid resuscitation
• Close monitoring for shock, bleeding, and organ dysfunction
• Adjust fluid therapy based on clinical response
• Target diuresis >0.5 ml/kg/hour in adults and >1 ml/kg/hour in children 1

Special Considerations

High-risk populations requiring closer monitoring:

• Pregnant women
• Older adults
• Children
• Patients with comorbidities (diabetes, hypertension, kidney/heart disease) 1

Discharge criteria:

• No fever for 48 hours without antipyretics
• Improving clinical status
• Increasing platelet count
• Stable hematocrit
• No respiratory distress
• Good urine output 1

Prevention

• Advise patients to prevent mosquito bites during the viremic phase
• Eliminate mosquito breeding sites
• Use repellents, appropriate clothing, and mosquito nets 1

Pitfalls and Caveats

• Cross-reactivity between dengue and other flaviviruses (especially Zika) can complicate serologic diagnosis 2
• Secondary dengue infections carry higher risk of severe disease due to antibody-dependent enhancement 1
• Fluid management requires careful balance - both dehydration and fluid overload can be dangerous 1
• Non-European descent, plasma protein level <6.5 mg/dl, platelets <30/nl, and aPTT >44s are associated with severe disease 3

With appropriate diagnosis and management following these guidelines, mortality from dengue can be reduced to less than 0.5% even in hospitalized patients 1.