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Microbiology · RNA arboviruses

Dengue virus !

  • Virus
  • Enveloped
  • Exam priority: high

A virus spread by the Aedes aegypti mosquito. It causes high fever and body aches and, in some people, plasma leakage that can lead to shock.

Updated 2026-11-01

Also called: DENV-1 to DENV-4, breakbone fever

At a glance

Shape
Spherical, icosahedral capsid
Genome
Single-stranded, positive-sense RNA
Envelope
Enveloped
Family
Flaviviridae, genus Orthoflavivirus
Size
About 50 nm

Morphology

  • Envelope carries glycoprotein E (attachment and fusion) and protein M
  • Four antigenically distinct serotypes (DENV-1, 2, 3 and 4)
  • The non-structural protein NS1 is secreted into blood and serves as a diagnostic antigen

Transmission

  • Bite of a female Aedes aegypti (and Aedes albopictus), by day
  • The mosquito is infected when it bites a viraemic person and transmits after an extrinsic incubation period
  • Rarely: transfusion, transplant or vertical spread near delivery

Reservoir: Humans (urban cycle); Non-human primates in sylvatic cycles on other continents

Vector: Aedes aegypti (main), Aedes albopictus

Isolation precautions

What the care team adds to standard precautions.

  • Standard

Virulence factors

  • Infection with one serotype gives lifelong immunity to it but only short-lived protection against the others
  • In a second infection with another serotype, non-neutralizing antibodies can help the virus enter monocytes (antibody-dependent enhancement)
  • NS1 and the inflammatory response damage the endothelial glycocalyx and raise capillary permeability
  • Plasma leakage causes haemoconcentration, effusions and shock; low platelets and coagulopathy favour bleeding

Diseases it causes

  • Dengue: without warning signs, with warning signs, and severe dengue Dengue →

Clinical picture

  • Febrile phase (2 to 7 days): high fever, headache, retro-orbital pain, myalgia, arthralgia, rash
  • Critical phase: starts as the fever breaks and lasts 24 to 48 hours; this is when plasma leaks
  • Warning signs (WHO/PAHO 2009): severe continuous abdominal pain, persistent vomiting, fluid accumulation, mucosal bleeding, lethargy or restlessness, liver enlargement and a rising haematocrit with falling platelets
  • Severe dengue: shock from plasma leakage or respiratory distress from fluid, severe bleeding or severe organ involvement
  • Recovery phase: fluid is reabsorbed, blood pressure stabilizes and platelets recover

Diagnosis

  • Days 0 to 7: NS1 antigen or RT-PCR on serum
  • IgM detectable from about day 3 to 5; the main test after day 7, lasting a few months
  • Positive tourniquet test, leukopenia and thrombocytopenia as classic clues
  • Serial haematocrit to watch for haemoconcentration
  • IgM cross-reacts with Zika and other flaviviruses

Treatment

There is no specific antiviral: care is supportive, with oral fluids or intravenous fluids guided by the classification and haematocrit, and paracetamol (acetaminophen) for fever. NSAIDs, aspirin and intramuscular injections are avoided because of bleeding risk.

Drug class only; doses and regimens are set by the clinician from the current guideline.

In Pharmacology:

Prevention

  • Remove breeding sites: cover, scrub or discard containers holding still water
  • Repellent, long sleeves, bed nets and window screens
  • Community vector control and entomological surveillance
  • A live attenuated tetravalent vaccine is licensed in some countries for certain ages in high-transmission areas

Vaccine: A live attenuated tetravalent vaccine is recommended by WHO for certain age groups in high-transmission settings; it is not part of Colombia's routine PAI schedule.

Test yourself

Think of the answer, then tap the question to see it.

When in dengue does plasma leakage happen?

In the critical phase, which starts as the fever breaks and lasts about 24 to 48 hours.

Which test fits a patient with two days of fever and suspected dengue?

NS1 antigen or RT-PCR on serum, useful during the first seven days; IgM may still be negative.

Why can a second dengue infection be more severe?

Antibodies from the first infection that do not neutralize the new serotype can help the virus enter cells (antibody-dependent enhancement).

What are three dengue warning signs?

Severe continuous abdominal pain, persistent vomiting, mucosal bleeding; also fluid accumulation, lethargy, liver enlargement and a rising haematocrit.

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← Back to the group: RNA arboviruses

Educational content on microorganisms; not a treatment guide and no substitute for a health professional's advice. No doses are given.

Sources: Dengue (World Health Organization (WHO), 2025); Clinical Features of Dengue (CDC, 2025); Clinical Testing Guidance for Dengue (CDC, 2025); Dengue: Symptoms, Prevention and Treatments (Pan American Health Organization (PAHO), 2025).

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