What are the symptoms of Dengue Fever?

Abdominal pain, Altered consciousness, Arthralgia, Bleeding gums, Bone pain.

Is Dengue Fever preventable by vaccination?

Yes, Dengue Fever is vaccine-preventable. Consult a travel health clinic for the recommended vaccination schedule.

How is Dengue Fever transmitted?

Blood transfusion, Congenital (mother-to-child), Mosquito Bite, Needle sharing, Vector Borne.

How is Dengue Fever treated?

No specific antiviral therapy. Management stratified by WHO severity classification: **Group A (outpatient — dengue without warning signs):** • Oral rehydration (ORS): 2–3 L/day minimum • Paracetamol for fever and pain (max 4 g/day in adults) • **AVOID:** NSAIDs (ibuprofen, aspirin, diclofenac) — increase bleeding risk • Daily platelet and hematocrit monitoring; return if warning signs develop **Group B (hospital observation — warning signs present):** • IV fluid: isotonic crystalloid (0.9% NaCl or Ringer lactate) at 5–7 mL/kg/hr • Strict fluid balance monitoring (avoid overhydration — pulmonary edema risk) • 6-hourly hematocrit and platelet monitoring • Monitor urine output (≥0.5 mL/kg/hr target) **Group C (emergency — severe dengue/DSS):** • Rapid IV fluid resuscitation: 10–20 mL/kg bolus over 15–30 min • Colloids if no response to crystalloid • Blood product transfusion for severe hemorrhage • ICU care; vasopressors for refractory shock • Platelet transfusion only for active bleeding with <10,000/mm³ (routine transfusion not recommended) **Critical phase:** Days 3–7 of illness (defervescence period) — this is when severe dengue develops. Paradoxically, patients often feel better as fever drops while plasma leakage peaks.

How can Dengue Fever be prevented?

**Vector control (primary prevention):** • Eliminate Aedes breeding sites: empty standing water containers, flower pots, old tires, water storage • Use mosquito repellent containing DEET (20–30%), picaridin, or IR3535 — reapply every 4–6 hours • Wear long sleeves and light-colored clothing (Aedes bites during daytime, especially early morning and late afternoon) • Sleep under permethrin-treated bed nets or in air-conditioned/screened rooms • Mosquito coils and electric vaporizers as supplementary measures **Vaccination:** • **Dengvaxia (CYD-TDV — Sanofi):** Live recombinant tetravalent vaccine; licensed in ~20 countries for ages 6–45 with confirmed prior dengue infection (seropositive). Contraindicated in seronegative individuals (increases severe dengue risk via ADE). 3-dose schedule (0, 6, 12 months). NOT recommended for travelers. • **TAK-003 (Qdenga — Takeda):** Live attenuated tetravalent; 2-dose schedule (0, 3 months); approved in EU, UK, Brazil, Indonesia, Thailand. Can be given regardless of prior dengue status. Efficacy ~80% against hospitalization. WHO recommended (2024) for high-burden settings. • No dengue vaccine is currently recommended for short-term travelers.

What are the complications of Dengue Fever?

Severe dengue (formerly "dengue hemorrhagic fever/dengue shock syndrome") occurs in 1–5% of cases: • **Dengue shock syndrome (DSS):** Plasma leakage causes hypovolemic shock • mortality 1–5% with treatment, 20–50% without. Critical window: hours around defervescence (days 3–7) • **Severe hemorrhage:** GI bleeding, hematemesis, menorrhagia • more common in secondary infections and patients on anticoagulants • **Organ involvement:** – Liver: Fulminant hepatitis (AST/ALT >1,000) • may progress to acute liver failure – Brain: Encephalitis, encephalopathy (rare, 0.5–6% of hospitalized dengue) – Heart: Myocarditis, cardiac arrhythmias – Kidneys: Acute kidney injury (AKI) from shock and rhabdomyolysis • **Fluid overload:** Iatrogenic complication from excessive IV fluids during recovery phase (plasma reabsorption causes fluid shifts → pulmonary edema, respiratory distress) • **Secondary infection risk factors:** Prior infection with different serotype (ADE), age extremes, pregnancy, chronic diseases (diabetes, asthma) • **Case fatality:** 20% if shock untreated

Dengue Fever — Symptoms, Prevention & Vaccines

Dengue Fever — which vaccine protects against it?

Get a free vaccination guide and a list of nearby clinics that offer it — straight to your inbox.

Traveler risk assessment

General risk

Low

Severe outcome

Very high

Preventable

Yes (vaccine)

Recovery

14–21 days

Long-term sequelae

20%

First-time travelers have low risk of severe dengue. Mosquito bite prevention is key — use DEET repellent, wear long sleeves, stay in air-conditioned rooms. If you develop high fever with severe headache/joint pain within 14 days of travel, seek care immediately. Avoid aspirin/ibuprofen.

Overview

Mosquito-borne viral infection causing high fever, severe pain, and potentially fatal hemorrhagic complications. The fastest-spreading arboviral disease globally with ~390 million infections per year.

Symptoms

Symptoms
Symptoms	Frequency	Severity	Onset
Arthralgia	55%	Moderate	Early
Bone pain	45%	Moderate	Early
Fatigue	70%	Mild	Early
High fever	97%	Severe	Early
Loss of appetite	55%	Mild	Early
Myalgia	85%	Moderate	Early
Nausea	60%	Mild	Early
Retro-orbital pain	70%	Moderate	Early
Severe headache	90%	Moderate	Early
Vomiting	45%	Mild	Early
Abdominal pain	40%	Mild	Early
Sore throat	35%	Mild	Early
Maculopapular rash	50%	Mild	Peak
Bleeding gums	15%	Severe	Peak
Bruising	10%	Mild	Peak
Hemorrhage	10%	Critical	Peak
Hepatomegaly	15%	Moderate	Peak
Hypotension	8%	Critical	Peak
Petechiae	20%	Severe	Peak
Tachycardia	12%	Severe	Peak
Altered consciousness	5%	Moderate	Peak
Edema	8%	Moderate	Peak
Itching	60%	Mild	Late
Swollen lymph nodes	30%	Mild	Any phase

Transmission

Mosquito BitePrimary route

Blood transfusion

Congenital (mother-to-child)

Needle sharing

Vector Borne

Overview

Dengue fever is a viral disease transmitted by mosquitoes, occurring in tropical and subtropical regions. It can cause severe flu-like symptoms and, in some cases, life-threatening complications.

Overview

Dengue is caused by four serotypes (DENV-1 to DENV-4) of the Dengue virus, a single-stranded RNA flavivirus transmitted primarily by Aedes aegypti (and secondarily by Ae. albopictus) mosquitoes. These day-biting urban mosquitoes breed in standing water near human habitation. Infection with one serotype confers lifelong immunity to that serotype but only temporary cross-protection (2–3 months) against others — subsequent infection with a different serotype carries increased risk of severe dengue due to antibody-dependent enhancement (ADE).

Emergency Signs

Seek emergency medical care immediately if:

Severe abdominal pain or persistent vomiting
Bleeding from gums, nose, or in vomit/stool
Rapid breathing or difficulty breathing
Extreme fatigue, restlessness, or confusion
Skin feels cold and clammy (sign of shock)
No urination for 4–6 hours
Symptoms worsening AFTER fever breaks (days 3–7) — this is the danger period
Rash that turns into bruise-like purple patches

Detailed Symptoms

Most common signs and symptoms

Incubation: 4–10 days (typically 5–7 days). WHO classifies dengue into three categories:

Dengue without warning signs:

Sudden high fever (40°C/104°F)
Severe headache (retro-orbital pain is characteristic)
Intense myalgia and arthralgia — "breakbone fever" (joint pain so severe it gave the disease its name)
Nausea, vomiting, anorexia
Maculopapular rash (appears days 3–7; may be pruritic)
Mild hemorrhagic manifestations: petechiae, positive tourniquet test
Leukopenia

Dengue with warning signs (critical to recognize — requires close monitoring):

Abdominal pain or tenderness
Persistent vomiting
Clinical fluid accumulation (ascites, pleural effusion)
Mucosal bleeding (gums, epistaxis)
Lethargy or restlessness
Liver enlargement >2 cm
Increasing hematocrit with decreasing platelets

Severe dengue (medical emergency):

Severe plasma leakage → shock (dengue shock syndrome — DSS)
Severe hemorrhage (GI bleeding, hematemesis)
Severe organ impairment (liver: AST/ALT >1000; brain: encephalitis; heart: myocarditis)

Knowing the symptoms is the first step to a quick response.

Course of Disease

Dengue can progress from mild to severe forms, including dengue hemorrhagic fever and dengue shock syndrome.

Diagnosis

How this disease is identified

Diagnosis depends on timing relative to fever onset:

Days 1–5 (acute/viremic phase): – NS1 antigen rapid test: sensitivity 60–95% (highest days 1–3); highly specific – RT-PCR: gold standard during viremia; identifies serotype
Days 5+: – Anti-dengue IgM (ELISA/rapid test): positive from day 5; persists 2–3 months. Cross-reacts with Zika and other flaviviruses. – Anti-dengue IgG: rises in secondary infection; IgG/IgM ratio >1.2 suggests secondary infection (higher ADE risk)
Full blood count (essential): – Rising hematocrit (>20% above baseline) = plasma leakage – Thrombocytopenia (<100,000/mm³) — correlates with severity – Leukopenia — common in first few days
Liver function: AST often elevated more than ALT (hepatitis pattern)
Tourniquet test: ≥20 petechiae per 1 inch² is positive (low sensitivity, moderate specificity)

NOTE: In dengue-endemic areas, NS1 + IgM combination testing provides optimal accuracy.

Treatment

Available treatment methods

No specific antiviral therapy. Management stratified by WHO severity classification:

Group A (outpatient — dengue without warning signs):

Oral rehydration (ORS): 2–3 L/day minimum
Paracetamol for fever and pain (max 4 g/day in adults)
AVOID: NSAIDs (ibuprofen, aspirin, diclofenac) — increase bleeding risk
Daily platelet and hematocrit monitoring; return if warning signs develop

Group B (hospital observation — warning signs present):

IV fluid: isotonic crystalloid (0.9% NaCl or Ringer lactate) at 5–7 mL/kg/hr
Strict fluid balance monitoring (avoid overhydration — pulmonary edema risk)
6-hourly hematocrit and platelet monitoring
Monitor urine output (≥0.5 mL/kg/hr target)

Group C (emergency — severe dengue/DSS):

Rapid IV fluid resuscitation: 10–20 mL/kg bolus over 15–30 min
Colloids if no response to crystalloid
Blood product transfusion for severe hemorrhage
ICU care; vasopressors for refractory shock
Platelet transfusion only for active bleeding with <10,000/mm³ (routine transfusion not recommended)

Critical phase: Days 3–7 of illness (defervescence period) — this is when severe dengue develops. Paradoxically, patients often feel better as fever drops while plasma leakage peaks.

Most cases are effectively treated with early diagnosis.

Prevention Details

How to protect yourself

Vector control (primary prevention):

Eliminate Aedes breeding sites: empty standing water containers, flower pots, old tires, water storage
Use mosquito repellent containing DEET (20–30%), picaridin, or IR3535 — reapply every 4–6 hours
Wear long sleeves and light-colored clothing (Aedes bites during daytime, especially early morning and late afternoon)
Sleep under permethrin-treated bed nets or in air-conditioned/screened rooms
Mosquito coils and electric vaporizers as supplementary measures

Vaccination:

Dengvaxia (CYD-TDV — Sanofi): Live recombinant tetravalent vaccine; licensed in ~20 countries for ages 6–45 with confirmed prior dengue infection (seropositive). Contraindicated in seronegative individuals (increases severe dengue risk via ADE). 3-dose schedule (0, 6, 12 months). NOT recommended for travelers.
TAK-003 (Qdenga — Takeda): Live attenuated tetravalent; 2-dose schedule (0, 3 months); approved in EU, UK, Brazil, Indonesia, Thailand. Can be given regardless of prior dengue status. Efficacy ~80% against hospitalization. WHO recommended (2024) for high-burden settings.
No dengue vaccine is currently recommended for short-term travelers.

Preparation is the best protection.

Travel Advice

Risk to travelers:

High risk: Southeast Asia (Thailand, Indonesia, Philippines, Vietnam), South Asia (India, Sri Lanka, Bangladesh), Latin America (Brazil, Mexico, Caribbean), Sub-Saharan Africa
Moderate risk: Pacific Islands, Southern China, Middle East
Emerging risk: Southern Europe (France, Italy, Spain) — autochthonous transmission
No vaccine is currently recommended for short-term travelers; prevention relies entirely on mosquito bite avoidance
Peak Aedes biting: early morning (6–9 AM) and late afternoon (4–7 PM) — do NOT rely on nighttime bed nets alone
Travelers returning with fever within 2 weeks of travel to endemic areas should be tested for dengue (and Zika, chikungunya — same vector)
Avoid aspirin and ibuprofen if dengue suspected — use only paracetamol for fever
Previous dengue infection increases risk of severe disease on re-exposure to a different serotype — disclose prior infection at travel clinic

How common is it?

Statistics and geographic data

Dengue is the most rapidly expanding arboviral disease globally. WHO estimates 390 million infections/year (96 million symptomatic), 500,000 severe dengue cases, and ~40,000 deaths annually. 2024 saw record-breaking outbreaks:

Americas: >16 million cases reported in 2024 (largest year ever); Brazil alone had >13 million suspected cases
Southeast Asia: Thailand, Vietnam, Philippines, Indonesia — endemic with periodic epidemics every 3–5 years
South Asia: India, Bangladesh, Sri Lanka — expanding range and intensity
Pacific Islands: Major outbreaks in endemic cycles
Africa: Emerging — likely vastly underreported; Burkina Faso, Kenya, Sudan outbreaks in 2024
Europe: Autochthonous (local) transmission confirmed in France, Italy, Spain (Ae. albopictus range expansion due to climate change)

Risk factors for expansion: urbanization, climate change (warmer temperatures expand Aedes range), globalization, and water storage practices. The disease has expanded from 9 endemic countries in 1970 to 130+ countries today.

Risk Factors

Who is most at risk

Traveling to endemic areas during peak transmission seasons, outdoor activities during mosquito activity hours.

Complications Details

Potential complications

Severe dengue (formerly "dengue hemorrhagic fever/dengue shock syndrome") occurs in 1–5% of cases:

Dengue shock syndrome (DSS): Plasma leakage causes hypovolemic shock
mortality 1–5% with treatment, 20–50% without. Critical window: hours around defervescence (days 3–7)
Severe hemorrhage: GI bleeding, hematemesis, menorrhagia
more common in secondary infections and patients on anticoagulants
Organ involvement: – Liver: Fulminant hepatitis (AST/ALT >1,000)
may progress to acute liver failure – Brain: Encephalitis, encephalopathy (rare, 0.5–6% of hospitalized dengue) – Heart: Myocarditis, cardiac arrhythmias – Kidneys: Acute kidney injury (AKI) from shock and rhabdomyolysis
Fluid overload: Iatrogenic complication from excessive IV fluids during recovery phase (plasma reabsorption causes fluid shifts → pulmonary edema, respiratory distress)
Secondary infection risk factors: Prior infection with different serotype (ADE), age extremes, pregnancy, chronic diseases (diabetes, asthma)
Case fatality: <1% with early recognition and proper fluid management
2–5% in severe dengue
20% if shock untreated

Recovery & Outlook

Expected outcomes and recovery

Prognosis is generally good with supportive care. Severe dengue can be life-threatening.

Dengue Fever — which vaccine protects against it?

Get a free vaccination guide and a list of nearby clinics that offer it — straight to your inbox.

Traveler risk assessment

General risk

Low

Severe outcome

Very high

Preventable

Yes (vaccine)

Recovery

14–21 days

Long-term sequelae

20%

Symptoms

Frequency

Severity

Onset

Arthralgia

55%

Moderate

Early

Bone pain

45%

Moderate

Early

Fatigue

70%

Mild

Early

High fever

97%

Severe

Early

Loss of appetite

55%

Mild

Early

Myalgia

85%

Moderate

Early

Nausea

60%

Mild

Early

Retro-orbital pain

70%

Moderate

Early

Severe headache

90%

Moderate

Early

Vomiting

45%

Mild

Early

Abdominal pain

40%

Mild

Early

Sore throat

35%

Mild

Early

Maculopapular rash

50%

Mild

Peak

Bleeding gums

15%

Severe

Peak

Bruising

10%

Mild

Peak

Hemorrhage

10%

Critical

Peak

Hepatomegaly

15%

Moderate

Peak

Hypotension

Critical

Peak

Petechiae

20%

Severe

Peak

Tachycardia

12%

Severe

Peak

Altered consciousness

Moderate

Peak

Edema

Moderate

Peak

Itching

60%

Mild

Late

Swollen lymph nodes

30%

Mild

Any phase

No specific antiviral therapy. Management stratified by WHO severity classification:

Group A (outpatient — dengue without warning signs):

Oral rehydration (ORS): 2–3 L/day minimum
Paracetamol for fever and pain (max 4 g/day in adults)
AVOID: NSAIDs (ibuprofen, aspirin, diclofenac) — increase bleeding risk
Daily platelet and hematocrit monitoring; return if warning signs develop

Group B (hospital observation — warning signs present):

IV fluid: isotonic crystalloid (0.9% NaCl or Ringer lactate) at 5–7 mL/kg/hr
Strict fluid balance monitoring (avoid overhydration — pulmonary edema risk)
6-hourly hematocrit and platelet monitoring
Monitor urine output (≥0.5 mL/kg/hr target)

Group C (emergency — severe dengue/DSS):

Rapid IV fluid resuscitation: 10–20 mL/kg bolus over 15–30 min
Colloids if no response to crystalloid
Blood product transfusion for severe hemorrhage
ICU care; vasopressors for refractory shock
Platelet transfusion only for active bleeding with <10,000/mm³ (routine transfusion not recommended)

Critical phase: Days 3–7 of illness (defervescence period) — this is when severe dengue develops. Paradoxically, patients often feel better as fever drops while plasma leakage peaks.

Flag	Country	Risk level
	Myanmar	High risk
	Peru	High risk
	Guyana	High risk
	Suriname	High risk
	Belize	High risk
	Solomon Islands	High risk
	Antigua and Barbuda	High risk
	Venezuela	High risk
	Maldives	High risk
	Guatemala	High risk

Flag	Country	Risk level
	Myanmar	High risk
	Peru	High risk
	Guyana	High risk
	Suriname	High risk
	Belize	High risk
	Solomon Islands	High risk
	Antigua and Barbuda	High risk
	Venezuela	High risk
	Maldives	High risk
	Guatemala	High risk

Dengue Fever — which vaccine protects against it?

Traveler risk assessment