Dengue Virus - Comprehensive Overview

Classification & Virology

• Sherris Medical Microbiology, 8th Ed.
• Robbins, Cotran & Kumar Pathologic Basis of Disease

Epidemiology

• 3.9 billion people in 128 countries are at risk; an estimated 390 million infections occur annually, of which ~96 million have clinical manifestations
• ~500,000 hospitalizations and 20,000-40,000 deaths per year
• Endemic throughout South/Southeast Asia, the Western Pacific, Central/South America, the Caribbean, Africa, and the Middle East
• Leading cause of febrile illness in returning travelers from the Caribbean, Latin America, and South Asia
• In the United States, dengue is endemic in Puerto Rico, US Virgin Islands, American Samoa, and Guam; imported cases are the main source in the continental US, though local outbreaks have occurred in Texas, Hawaii, and Florida
• Incidence peaks July through September in the Northern Hemisphere
• Red Book 2021, Report of the Committee on Infectious Diseases
• Rosen's Emergency Medicine, 9th Ed.

Transmission & Vector

• Primary vector: Aedes aegypti (daytime-biting peridomestic mosquito)
• Secondary vectors: Aedes albopictus, Aedes polynesiensis
• Transmission cycle: human → mosquito → human (no direct human-to-human spread)
• The extrinsic incubation period in mosquitoes is 8-12 days; the intrinsic incubation period in humans is 3-14 days (typically 4-7 days)
• Viremic humans - both symptomatic AND asymptomatic - can infect mosquitoes 1-2 days before symptoms and throughout the ~7-day viremic period
• Less common routes: vertical/perinatal transmission (~20% rate, higher near delivery), blood/organ transfusion, breastfeeding, needlestick, and rarely sexual transmission
• A sylvatic cycle involving non-human primates exists in parts of Africa and Southeast Asia
• Red Book 2021
• Sherris Medical Microbiology

Pathogenesis & Immunity

• A lifetime maximum of 4 dengue infections is possible (one per serotype)
• ADE also underlies concerns about dengue vaccines in seronegative individuals
• Robbins, Cotran & Kumar Pathologic Basis of Disease
• Red Book 2021

Clinical Manifestations

1. Dengue Without Warning Signs

• Fever + ≥2 of: nausea/vomiting, rash, aches/pains, leukopenia, positive tourniquet test
• Classic "breakbone fever": sudden high fever (2-7 days), severe myalgias/arthralgias/bone pain, headache, retro-orbital pain, facial erythema, maculopapular rash, petechiae

2. Dengue With Warning Signs (requires close monitoring)

3. Severe Dengue (dengue hemorrhagic fever / dengue shock syndrome)

• Severe plasma leakage → hypovolemic shock (dengue shock syndrome, DSS) or fluid accumulation with respiratory distress
• Severe bleeding (spontaneous hemorrhage)
• Severe organ involvement: AST or ALT ≥1000 IU/L, impaired consciousness, cardiac or organ failure

• Red Book 2021
• Rosen's Emergency Medicine
• Robbins Pathology

Diagnosis

• Red Book 2021
• Rosen's Emergency Medicine

Management

Dengue Fever (non-severe)

• Rest, oral hydration, antipyretics (paracetamol only)
• Avoid: aspirin, ibuprofen, and other NSAIDs - increase bleeding risk
• Can be managed as outpatient if no warning signs

Severe Dengue / DHF / DSS

• Hospital admission; ICU for DSS
• IV fluid resuscitation (crystalloids first; colloids and blood products for refractory shock)
• Monitor closely for occult bleeding, hemoconcentration, and plasma leak
• During the convalescent phase: watch for fluid overload as extravascular fluid reabsorbs and hematocrit drops
• Blood product transfusions for hemorrhagic complications
• Steroids: evidence is inconclusive; not recommended routinely
• Rosen's Emergency Medicine
• Red Book 2021

Prevention & Vaccines

Vector Control

• Eliminate standing water (mosquito breeding sites)
• Screens, air conditioning, insect repellents (EPA-registered DEET, picaridin, IR3535)
• Daytime protection (Aedes bite during daylight hours)
• Novel: Wolbachia-infected Aedes release has reduced dengue cases by 95-97% in Colombia - a promising biocontrol strategy
  • Robbins Pathology

Vaccines (Current Status 2025-2026)

• Live recombinant tetravalent chimeric vaccine (YF-dengue chimera)
• 3-dose schedule (0, 6, 12 months)
• FDA-approved (2019) for ages 9-16 in US territories with prior laboratory-confirmed dengue infection only
• Critical safety issue: In seronegative recipients, subsequent dengue infection carries a higher risk of severe disease (ADE mechanism) - therefore pre-vaccination serological testing is mandatory
• Approved in ~17 endemic countries for ages 9-45 years

• Tetravalent live attenuated vaccine; DEN-2 backbone with attenuated genes from DEN-1, 3, 4
• 2-dose schedule (0, 3 months), subcutaneous
• Phase 3 TIDES trial: >20,000 children aged 4-16; 7-year follow-up data published November 2025 showed sustained protection against infection and hospitalization
• Added to Brazil's national immunization program in 2024
• WHO-SAGE has recommended consideration for TAK-003
• Rare anaphylaxis cases reported (4.4/100,000 doses in Brazil pharmacovigilance)
• Red Book 2021

High-Risk Groups

• Infants with maternal dengue antibodies (ADE susceptibility)
• Pregnant women (increased severity risk)
• Patients with chronic diseases (asthma, sickle cell anemia, diabetes)
• Elderly (>60 years): higher severe disease and death rates
• Second infection with a heterologous serotype (especially DENV-2 secondary)

Key Points Summary

Recent evidence note (PMID 41037858): A 2025 systematic review in J Infect Public Health specifically covers dengue pathogenesis, diagnosis, and management - consistent with the above.