What are the typical symptoms, warning signs, and recommended management for dengue infection?

Symptoms of Dengue Fever

Dengue fever classically presents with sudden onset of high fever, severe headache, retro-orbital (behind the eyes) pain, muscle and joint pain (often called "breakbone fever"), and a characteristic rash, with an incubation period of 4-8 days after mosquito bite. 1, 2

Classic Clinical Presentation

The typical dengue infection manifests as an acute febrile illness with the following core symptoms:

• Fever - sudden onset, high-grade fever is the hallmark symptom 1, 3
• Severe headache - frontal headache is characteristic 4, 3
• Retro-orbital pain - pain behind the eyes, worsened by eye movement 1, 3, 5
• Myalgia and arthralgia - severe muscle and joint pains, giving dengue its nickname "breakbone fever" 1, 3, 5
• Skin rash - characteristic rash similar to measles, though not always present 1, 5
• General malaise and chills 3
• Nausea and vomiting 4, 6
• Diarrhea may occur 6

Critical Warning Signs Requiring Immediate Medical Attention

The most important clinical skill is recognizing warning signs that indicate progression to severe dengue, which typically appear around days 3-7 of illness during the defervescence (fever resolution) phase. 4

Warning signs that mandate close monitoring or hospitalization include:

• Persistent vomiting - unable to tolerate oral fluids 2, 4
• Severe abdominal pain or tenderness - particularly right upper quadrant pain from liver involvement 2, 4
• Clinical fluid accumulation - pleural effusions, ascites 4
• Mucosal bleeding - gum bleeding, nosebleeds, heavy menstrual bleeding 2, 4
• Lethargy or restlessness - altered mental status 2, 4
• Hepatomegaly - liver enlargement >2 cm 4
• Rising hematocrit with concurrent rapid platelet drop - indicates plasma leakage 2, 4

Disease Spectrum and Severity Classification

Dengue presents along a spectrum from mild to life-threatening disease:

Dengue Without Warning Signs (>90% of cases)

• Mild febrile illness with the classic symptoms described above 4, 7
• Self-limiting course, typically resolving within 5-7 days 8
• Can be managed as outpatient with close monitoring 2

Dengue Hemorrhagic Fever (DHF)

• Characterized by minor or major bleeding phenomena, thrombocytopenia (platelet count <100,000/mm³), and evidence of plasma leakage 1, 4
• Mortality 1-5% with appropriate treatment 7

Dengue Shock Syndrome (DSS)

• All DHF criteria plus hypotension (systolic BP <90 mmHg for >30 minutes) or narrow pulse pressure (<20 mmHg) 4
• Represents the most severe form requiring intensive care 4
• Signs include cold, clammy extremities, capillary refill time ≥3 seconds, and elevated lactate >2 mmol/L 4

Triphasic Disease Course

Understanding the triphasic pattern is critical for anticipating complications:

1. Febrile phase (days 1-3) - high fever with constitutional symptoms 7
2. Critical phase (days 3-7) - defervescence occurs, but this is when warning signs appear and plasma leakage begins 4, 7
3. Recovery phase (days 7-10) - reabsorption of extravasated fluid, clinical improvement 7

Common Pitfalls to Avoid

• Do not assume fever resolution means improvement - the critical phase with plasma leakage typically begins as fever subsides 4, 7
• Never use aspirin or NSAIDs - these increase bleeding risk; acetaminophen is the only safe antipyretic 2, 8
• Do not miss the narrow pulse pressure - this is an earlier and more sensitive indicator of shock than absolute hypotension 4
• Absence of thrombocytopenia significantly reduces dengue probability - making it a useful rule-out finding 2

When to Suspect Dengue

Suspect dengue in any patient with:

• Fever plus at least one of: nausea, vomiting, rash, headache, retro-orbital pain, myalgia, arthralgia, or leukopenia 2
• Travel to or residence in endemic areas (Asia, South America, Caribbean, Africa) within the past 14 days 1
• Exposure during day-biting hours (Aedes mosquitoes are day-biters) 1

Diagnostic Confirmation

• Days 1-7 of symptoms: PCR/NAAT or NS1 antigen detection on serum 2, 4
• After day 7: IgM capture ELISA becomes the primary test 2
• Cross-reactivity warning: Document complete flavivirus vaccination history (yellow fever, Japanese encephalitis, tick-borne encephalitis) as these cause false-positive IgM results 2

High-Risk Populations

Certain patients warrant lower threshold for hospitalization:

• Pregnant women - risk of maternal death, hemorrhage, preeclampsia, and vertical transmission 2
• Age >60 years 2
• Comorbidities: diabetes with hypertension (2.16× higher risk of DHF), heart disease, immunocompromised states 2

Early recognition of warning signs and appropriate fluid management can reduce case-fatality rates to <0.5%. 4