# Dengue Fever > 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. Source: https://medova.health/en/knowledge/diseases/dengue-fever · Language: en ## 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. ## Medical Information - ICD-10: A90 - ICD-11: 1D40 - Causative Agent: virus - Severity: Severe - Incubation Period: 3–14 days - Infectious Period: 4–5 days - Mortality Rate: 1% - Vaccine available: Yes ## Symptoms - Arthralgia (55%) - Bone pain (45%) - Fatigue (70%) - High fever (97%) - Itching (60%) - Loss of appetite (55%) - Maculopapular rash (50%) - Myalgia (85%) - Nausea (60%) - Retro-orbital pain (70%) - Severe headache (90%) - Swollen lymph nodes (30%) - Vomiting (45%) - Abdominal pain (40%) - Bleeding gums (15%) - Bruising (10%) - Hemorrhage (10%) - Hepatomegaly (15%) - Hypotension (8%) - Petechiae (20%) - Sore throat (35%) - Tachycardia (12%) - Altered consciousness (5%) - Edema (8%) ## Transmission - Mosquito Bite (Primary 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 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) ## Course of Disease Dengue can progress from mild to severe forms, including dengue hemorrhagic fever and dengue shock syndrome. ## Diagnosis 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 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. ## Prevention Details **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. ## 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? 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 Traveling to endemic areas during peak transmission seasons, outdoor activities during mosquito activity hours. ## Complications Details 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 Prognosis is generally good with supportive care. Severe dengue can be life-threatening. ## Available Vaccines - [Dengue Vaccine](https://medova.health/en/knowledge/vaccines/dengue-vaccine) ## Sources & content verification - Data sources: WHO/ICD-11, CDC Yellow Book 2024, ECDC (SafeTripVax QMR-004, 2026-03-23), WHO Disease Factsheets 2024 + CDC Travelers' Health 2024 + Heymann CDD 21st ed. - Generated by: AI + Human review - Review status: Awaiting medical review - Last updated: 2026-03-29 - [www.who.int](https://www.who.int/emergencies/disease-outbreak-news) --- 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 use](https://medova.health/en/terms)