Conditions · Systemic conditions
Zika virus infection !
Zika is a virus spread mainly by Aedes mosquitoes; it is usually mild with rash and red eyes, but in pregnancy it can cause birth defects such as microcephaly.
Updated 2026-10-30
Structures involved
Tap one to see what it is and open it in 3D.
Microorganisms that cause it
In immunology
In embryology
Why it happens
What it is
A flavivirus infection spread mainly by Aedes mosquitoes, usually mild with rash and conjunctivitis, but infection during pregnancy can cause congenital Zika syndrome, including microcephaly.
Who gets it
Spread through the Americas in 2015–2016, with a large outbreak in Colombia, where health ministry bulletins recorded 92,891 cumulative suspected and confirmed cases from August 2015 to July 2016. Transmission later fell. It persists at low levels where Aedes aegypti is present.
Causes
- Zika virus (Flaviviridae family)
- Bite of infected Aedes aegypti or Aedes albopictus
- Sexual transmission
- Mother-to-fetus transmission during pregnancy
- Rarely: blood transfusion
Risk factors
- Living in or travelling to areas with Aedes mosquitoes
- Pregnancy (risk to the fetus, highest in the first trimester)
- Unprotected sex with a partner exposed to the virus
Pathophysiology
The virus replicates in skin cells and spreads in blood. It crosses the placenta and infects neural progenitor cells of the developing brain, causing cell death and disrupted growth of the cortex, which leads to microcephaly and brain calcifications. Post-infectious immune reactions can cause Guillain–Barré syndrome.
Classification
- Acute Zika infection (often asymptomatic)
- Congenital Zika syndrome
- Neurologic complications in adults (Guillain–Barré syndrome)
Symptoms and signs
- Itchy maculopapular rash
- Non-purulent conjunctivitis (red eyes)
- Low-grade fever
- Joint pain and swelling of small joints
- Headache and muscle aches
- Many infections cause no symptoms
Diagnosis
- Clinical
- Rash, conjunctivitis and mild fever in someone exposed in an area with Aedes transmission; pregnancy status is always asked.
- Tests
- RT-PCR on blood or urine in the first days; IgM serology later, which cross-reacts with dengue and may need neutralization tests to confirm.
- Imaging
- Serial fetal ultrasound in exposed pregnancies to follow head size and brain anatomy; after birth, head ultrasound, CT or MRI shows calcifications and ventricular enlargement.
Differential diagnosis
- Dengue
- Chikungunya
- Measles
- Rubella
- Other congenital infections (TORCH: toxoplasmosis, cytomegalovirus)
- Parvovirus B19 infection
Goal of treatment
Relieve symptoms, protect pregnancies from infection, and detect and support infants with congenital Zika syndrome as early as possible.
Treatment
- Conservative
- Rest, fluids and paracetamol (acetaminophen); NSAIDs avoided until dengue is excluded. No specific antiviral exists.
- Follow-up
- Prenatal follow-up with serial ultrasound when infection or exposure occurs in pregnancy.
- Rehabilitation
- For affected infants: early multidisciplinary care with neurology, physical therapy, feeding support, vision and hearing assessment.
- Acute
- Guillain–Barré syndrome: hospital care, breathing monitoring, and immunotherapy (intravenous immunoglobulin or plasma exchange).
Complications
- Congenital Zika syndrome: severe microcephaly with partially collapsed skull
- Brain calcifications, thin cortex and ventricular enlargement
- Eye damage: macular scarring and chorioretinal changes
- Joint contractures (arthrogryposis), excess muscle tone, swallowing problems and seizures
- Guillain–Barré syndrome in adults
- Miscarriage or stillbirth
Prognosis
In most adults the illness is mild and short. Congenital Zika syndrome causes lifelong neurological disability of varying severity.
Prevention
- Mosquito control and personal protection (repellents, screens, clothing)
- Pregnant women avoiding travel to areas with active transmission
- Condoms or abstinence during pregnancy if a partner may be exposed
- No licensed vaccine is widely available
Test yourself
Think of the answer, then tap the question to see it.
What are the main features of congenital Zika syndrome?
Severe microcephaly with partially collapsed skull, subcortical calcifications, macular scarring and chorioretinal changes, joint contractures and early hypertonia.
Besides mosquitoes, how else is Zika virus transmitted?
Sexually, from mother to fetus across the placenta, and rarely by blood transfusion.
Which neurological complication of Zika is seen in adults?
Guillain–Barré syndrome, an acute ascending inflammatory polyneuropathy.
Why can Zika serology be hard to interpret in Colombia?
Zika IgM antibodies cross-react with dengue and other flaviviruses, so neutralization tests may be needed to confirm.
Related conditions
Educational information, not medical advice. For any symptom, see a health professional.
Sources: Zika Virus (StatPearls (NCBI Bookshelf), 2026); Forecasting Zika Incidence in the 2016 Latin America Outbreak Combining Traditional Disease Surveillance with Search, Social Media, and News Report Data (PLoS neglected tropical diseases, 2017) · adapted, CC BY 4.0.
Spotted a mistake?We are always improving for the community. Tell us what is wrong and our team will review it.Report a mistake
Representative model, for educational purposes only.
