Dengue

Acute systemic viral infection caused by the dengue virus (DENV), a single-stranded RNA virus of the Flaviviridae family, transmitted to humans by the bite of infected Aedes mosquitoes, primarily Aedes aegypti.

Aetiology

• DENV-1

• DENV-2

• DENV-3

• DENV-4

Pathophysiology

• Virus enters via mosquito bite and infects dendritic cells

• Viremia leads to immune activation and cytokine release

• Antibody-dependent enhancement (ADE) during secondary infection increases viral entry into macrophages

• Increased capillary permeability results in plasma leakage, hemoconcentration, and shock

• Thrombocytopenia and coagulopathy contribute to bleeding manifestations

Clinical presentation

Clinical Classification (WHO 2009)

• Acute fever

• Headache

• Retro-orbital pain

• Myalgia and arthralgia

• Nausea and vomiting

• Rash

• Mild leukopenia

• Abdominal pain or tenderness

• Persistent vomiting

• Clinical fluid accumulation (ascites, pleural effusion)

• Mucosal bleeding

• Lethargy or restlessness

• Hepatomegaly (>2 cm)

• Rising hematocrit with rapid platelet decline

• Severe plasma leakage leading to:
• Dengue shock syndrome (DSS)
• Respiratory distress

• Severe bleeding

• Severe organ involvement (liver, CNS, heart)

Investigations

Hematological

• Thrombocytopenia

• Leukopenia

• Hemoconcentration (↑ hematocrit)

Virological and Serological Tests

• NS1 antigen (early phase)

• RT-PCR (early diagnosis and serotyping)

• IgM and IgG antibodies (later phase)

Other Investigations

• Liver function tests (↑ AST > ALT)

• Coagulation profile (severe dengue)

• Chest X-ray / ultrasound (plasma leakage)

Management

Supportive Care (Mainstay of Treatment)

• Careful fluid management (oral or IV)

• Paracetamol for fever (avoid NSAIDs and aspirin)

• Close monitoring of:
• Vital signs
• Urine output
• Hematocrit and platelet count

Management of Severe Dengue

• Prompt IV isotonic crystalloid fluids

• Blood products for significant bleeding

• ICU care for shock or organ failure