Zika virus !

Virus
Enveloped
Exam priority: high

A virus spread by Aedes mosquitoes, and also sexually and from mother to fetus. It is usually mild, but in pregnancy it can cause microcephaly.

Updated 2026-11-01

Also called: ZIKV

At a glance

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

Morphology

Enveloped virus with surface protein E, structurally close to dengue virus
A single serotype

Transmission

Bite of Aedes aegypti (main) and Aedes albopictus
Vertical: mother to fetus during pregnancy
Sexual
Blood transfusion; possibly organ transplant

Reservoir: Humans in the urban cycle; Non-human primates in the African sylvatic cycle

Vector: Aedes aegypti, Aedes albopictus

Isolation precautions

What the care team adds to standard precautions.

Standard

Virulence factors

Tropism for fetal neural progenitor cells: it halts their growth and kills them, so the brain grows less
Crosses the placenta and can persist in semen for weeks
The post-infectious immune response can attack peripheral nerves (Guillain–Barré)

Diseases it causes

Zika: mild fever, itchy rash and non-purulent conjunctivitis Zika virus infection →
Congenital Zika syndrome: microcephaly, brain calcifications, eye lesions, contractures and hearing loss
Guillain–Barré syndrome and other neurological complications Guillain-Barré syndrome →

Clinical picture

About half or more of infections are asymptomatic
Itchy maculopapular rash, low fever, non-purulent conjunctivitis, mild arthralgia
Birth defects can occur even when the mother had no symptoms
In pregnancy it is also linked to fetal loss, stillbirth and preterm birth

Diagnosis

RT-PCR on blood or urine in the acute phase
Serum IgM, which cross-reacts with dengue and may need neutralization tests
Serial obstetric ultrasound for microcephaly and calcifications in exposed pregnancies

Treatment

There is no specific antiviral: rest, fluids and paracetamol for fever and pain. NSAIDs are avoided until dengue is ruled out. Exposed newborns are followed for neurodevelopment, vision and hearing.

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

Prevention

Control of Aedes breeding sites and bite protection, especially in pregnancy
Condoms or abstinence during pregnancy if the partner was in an area with transmission
No vaccine is available

Test yourself

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

Which routes of spread set Zika apart from other arboviruses?

Besides the Aedes mosquito, it spreads sexually and from mother to fetus during pregnancy.

What are the main findings of congenital Zika syndrome?

Microcephaly, brain calcifications, eye lesions, joint contractures (arthrogryposis), high muscle tone and hearing loss.

Which adult neurological complication is linked to Zika?

Guillain–Barré syndrome, an acute post-infectious inflammatory polyradiculoneuropathy.

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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: Zika virus (World Health Organization (WHO), 2025); Appendix A: Type and Duration of Precautions Recommended for Selected Infections and Conditions (CDC, 2024).

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Representative model, for educational purposes only.