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How serious?
Risk of death
Yes
Vaccine available?
Time to symptoms
Countries affected
Active outbreaks
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.
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 | 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 |
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.
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).
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
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.
Dengue can progress from mild to severe forms, including dengue hemorrhagic fever and dengue shock syndrome.
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.
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.
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.
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
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.
Who is most at risk
Traveling to endemic areas during peak transmission seasons, outdoor activities during mosquito activity hours.
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
Expected outcomes and recovery
Prognosis is generally good with supportive care. Severe dengue can be life-threatening.
This disease is vaccine-preventable. Effective protection is available through vaccination.
Talk to a travel health specialist about the recommended schedule before your trip.
Find a vaccination clinic →The content on this page is for informational and educational purposes only. It does not constitute medical advice, diagnosis, or treatment recommendations. If you have health concerns, consult a qualified healthcare professional. Medova is not a medical service provider.
Full terms of useGeographic distribution and active outbreaks
| 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 |
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