Dengue — Signs & Symptoms and diagnosis

Dengue — Signs & Symptoms

Typical onset: 4–10 days after an infected mosquito bite.

1. Febrile phase (usually 2–7 days)

• Sudden high-grade fever
• Severe headache
• Retro-orbital pain (pain behind eyes)
• Marked muscle and joint pains (“break-bone” pain)
• Nausea/vomiting
• Rash, often appearing around day 3–5
• Mild bleeding: gum/nose bleeding, easy bruising

2. Warning signs — usually around defervescence (day 3–7)

• Severe or persistent abdominal pain
• Persistent vomiting
• Mucosal bleeding
• Lethargy/restlessness
• Clinical fluid accumulation
• Hepatomegaly
• Rising hematocrit with rapidly falling platelet count

3. Severe dengue

• Shock/hypotension due to plasma leakage
• Severe bleeding
• Severe organ involvement: liver, brain, heart or kidneys
• Altered consciousness
• Respiratory distress

Key clinical point: The critical phase often begins when the fever starts settling, so apparent improvement in temperature does not necessarily mean recovery.

Diagnostic approach:

# Suspected dengue ≤5 days: NS1 antigen ± RT-PCR.

# >5 days: IgM ± NS1.

# Severe dengue: diagnosis should not wait for laboratory confirmation—assess CBC/platelets, hematocrit, LFT, renal function and coagulation along with dengue-specific testing.

Important: A negative NS1/RT-PCR does not exclude dengue, particularly when testing is performed late in the illness.