What is dengue fever and how is it managed?

Dengue Fever: Overview and Management

Dengue fever is a mosquito-borne viral disease transmitted primarily by Aedes aegypti mosquitoes, characterized by fever, headache, retro-orbital pain, myalgia, arthralgia, and rash, with potential progression to severe forms including dengue hemorrhagic fever and dengue shock syndrome in a small percentage of cases. 1, 2

Epidemiology and Transmission

• Endemic in over 100 countries throughout the tropics and subtropics, particularly in Asia and South America 1, 2
• Annual global incidence of 50-100 million symptomatic infections and approximately 13,000 deaths 1, 2
• Incidence has doubled each decade since 1990 1, 2
• Transmitted by day-biting Aedes mosquitoes, primarily Aedes aegypti 1
• Incubation period of 3-14 days (typically 4-8 days) 1, 2

Clinical Presentation

Dengue presents with a spectrum of clinical manifestations:

Classic Dengue Fever

• Acute febrile illness with:
  • Frontal headache
  • Retro-orbital pain
  • Severe myalgia and arthralgia (particularly back pain, hence "breakbone fever")
  • Rash
  • Nausea and vomiting 1, 2

Severe Forms

1. Dengue Hemorrhagic Fever (DHF):

   • Minor or major bleeding phenomena
   • Thrombocytopenia (≤100,000/mm³)
   • Evidence of plasma leakage (hemoconcentration with hematocrit increased by ≥20%) 1, 2

2. Dengue Shock Syndrome (DSS):

   • All criteria for DHF plus:
   • Hypotension or narrow pulse pressure (≤20 mmHg) 1, 2

Disease Phases

1. Febrile phase: Lasts 2-7 days 2
2. Critical phase: 24-48 hours when fever subsides (highest risk for severe complications) 2
3. Recovery phase: 48-72 hours 2

Diagnosis

Laboratory Testing

• Acute phase (≤7 days from symptom onset):

  • RT-PCR for dengue virus RNA in serum
  • NS1 antigen detection 1, 2

• Convalescent phase (>5-7 days):

  • IgM antibody detection (may persist for months)
  • Demonstration of fourfold rise/fall in IgG or IgM antibody titers in paired samples 1, 2

Essential Laboratory Tests

• Complete blood count with hematocrit and platelet count
• Liver function tests
• Coagulation profile 2

Case Classification

• Probable case: Clinically compatible with supportive serology (IgG titer ≥1280 or positive IgM)
• Confirmed case: Clinically compatible and laboratory confirmed by virus isolation, nucleic acid detection, or serologic confirmation 1

Management

Mild to Moderate Dengue

• Supportive care with focus on adequate hydration
• Acetaminophen/paracetamol for fever and pain
• Avoid NSAIDs and aspirin due to bleeding risk
• Rest and symptomatic treatment 2, 3

Severe Dengue (DHF/DSS)

• Fluid resuscitation:

  • Crystalloids as first-line treatment (5-10 ml/kg/hour)
  • Adjust according to clinical response
  • Consider colloids if hemodynamic deterioration occurs despite adequate crystalloid administration 2

• Monitoring:

  • Vital signs every 1-2 hours during critical phase
  • Hematocrit every 6-12 hours
  • Fluid balance
  • Signs of capillary leak (edema, ascites, pleural effusion) 2

• Treatment goals:

  • Diuresis >0.5 ml/kg/hour in adults and >1 ml/kg/hour in children
  • Semi-recumbent position (head elevated 30-45°) 2

• For refractory shock:

  • Consider vasopressors (dopamine, epinephrine, or norepinephrine)
  • Transfusion of blood products for significant bleeding 2

Warning Signs Requiring Close Monitoring

• Abdominal pain or tenderness
• Persistent vomiting
• Clinical fluid accumulation
• Mucosal bleeding
• Lethargy or restlessness
• Liver enlargement
• Rising hematocrit with falling platelet count 2

Prevention and Control

• Vector control through elimination of mosquito breeding sites
• Use of larvicides and insecticides
• Personal protection with repellents, appropriate clothing, and mosquito nets
• A tetravalent vaccine (Dengvaxia) is available in some countries but recommended only for those with confirmed previous dengue infection 2

Prognosis

• Most cases recover completely with appropriate supportive care
• Case fatality rate in severe dengue with proper management can be reduced to less than 0.5% 2
• 90% of DHF cases occur in children under 15 years of age 4

Common Pitfalls in Management

• Delayed recognition of warning signs and progression to severe disease
• Inadequate fluid resuscitation during critical phase
• Excessive fluid administration leading to fluid overload
• Inappropriate use of NSAIDs or aspirin increasing bleeding risk
• Prophylactic platelet transfusions, which are not recommended 2