Dengue

Dengue is a viral disease transmitted by mosquitoes (especially Aedes aegypti) and is widely distributed throughout the tropics and subtropics. Dengue classically presents with high fever, headache, body aches, exanthem, and generalized lymphadenopathy. Symptoms usually subside within one week. Some cases progress to the more severe dengue hemorrhagic fever (DHF) with thrombocytopenia, spontaneous bleeding, and potentially shock (dengue shock syndrome). Treatment is supportive. A vaccination is available for use in children, living in endemic areas, with confirmed prior dengue virus infection.

• Distribution: tropical regions worldwide, particularly Asia (e.g., Thailand)
• Incidence
  • Most common viral disease affecting tourists in tropical regions
  • ∼ 400 million infections per year worldwide

References:^[1]

Epidemiological data refers to the US, unless otherwise specified.

• Pathogen
  • Dengue virus (Serotype: DENV 1–4)
  • RNA virus of the genus Flavivirus
• Transmission route ^[2]
  • Vector-borne; : mosquitoes most commonly from the species Aedes aegypti

References:^[3]

If symptoms appear more than 2 weeks after returning from a dengue-endemic region, it is very unlikely that dengue is the cause.

Severe dengue is more frequent in individuals who experience a repeat infection with a second serotype, especially serotype 2.

Laboratory tests

• Leukopenia
• Neutropenia
• Thrombocytopenia
• ↑ AST
• Hct significantly increased or decreased in DHF (due to plasma leakage)

Confirmation of diagnosis ^[6]

Acute phase (≤ 7 days after symptom onset)

• Serologic tests: MAC-ELISA to detect IgM
• Molecular Tests (NAAT) to detect viral RNA
• NS1 antigen test: detection of the Dengue NS1 antigen (Dengue non-structural protein 1) via ELISA ^[7]
  • Allows early detection of the viral antigen in the serum
  • A positive test confirms the diagnosis (without identifying the dengue serotype)
  • A negative test does not rule out dengue infection; IgM testing should be performed
  • Not recommended after day 7 of symptomatic infection (low sensitivity)
• Tissue tests (IHC)

Convalescent phase (i.e., > 7 days after symptom onset)

• Serologic tests (IgM, IgG)
• Molecular Tests (NAAT)
• Tissue tests (IHC)

• Chikungunya fever and other viral hemorrhagic fevers
• Malaria
• Zika virus infection

Severe hemorrhagic manifestations with shock and death as well as decreased neutrophil and platelet counts are more indicative of Dengue fever than Chikungunya fever.

The differential diagnoses listed here are not exhaustive.

• Symptomatic treatment
  • Fluid administration to avoid dehydration
  • Acetaminophen
• Dengue with warning signs and severe dengue
  • Blood transfusions in case of significant internal bleeding (e.g., epistaxis, gastrointestinal bleeding, or menorrhagia)
  • Urgent resuscitation with IV fluids

• Avoid exposure, use of mosquito repellent (see also → mosquito bite prevention)
• A tetravalent attenuated live vaccine (CYD-TDV)
  • Recombinant yellow fever virus in which genetic material coding for the Dengue virus envelope and premembrane proteins has been inserted
  • Has been approved for use in children between 9–16 years of age who live in endemic areas and have a laboratory confirmed prior dengue virus infection.

References:^{[8][9][10][11][12]}