Embryology · Teratology and prenatal diagnosis
Congenital Zika syndrome !
- Teratogen
Zika infection in pregnancy can damage the baby's brain and eyes; Colombia had an epidemic in 2015–2016.
Updated 2026-11-01
Also called: Colombia: according to the CDC, in epidemiological weeks 5 to 45 of 2016 there were 476 reported microcephaly cases versus 110 in the same period of 2015, about a 4.5-fold rise., The microcephaly peak (week 28 of 2016) came about 24 weeks after the Zika peak in pregnant women (week 4)., Colombia's Instituto Nacional de Salud (INS) set up intensified surveillance of microcephaly and other central nervous system birth defects due to Zika, reported to Sivigila, after PAHO's December 2015 alert.
See it in 3D: Corpus callosum · Cerebellum · Lateral ventricles · Retina · Optic nerve · Diaphragm
What it is
Zika virus is a flavivirus spread by the Aedes mosquito; it can also pass sexually and from mother to fetus. It infects progenitor cells of the developing brain and causes congenital Zika syndrome: severe microcephaly, a thin cortex with calcifications, eye lesions and joint contractures. Risk is highest with infection in the first trimester and early second trimester.
Key facts
- Findings that set Zika apart among congenital infections: diaphragmatic paralysis and neurogenic bladder.
- Third-trimester infection is linked to less severe brain and eye defects.
- It is also associated with miscarriage, stillbirth and neonatal death.
- Colombia confirmed local transmission in October 2015.
- Between August 2015 and November 2016 about 105,000 suspected cases were reported, nearly 20,000 in pregnant women.
Critical period and mechanism
- Critical period: first trimester and early second trimester, while cortical neurons proliferate and migrate.
- The virus crosses the placenta and infects neural progenitor cells.
- Their death halts brain growth; the skull collapses over a small brain.
- Nervous system damage explains the contractures, hypertonia and bladder and diaphragm dysfunction.
Prevention
- Avoiding Aedes mosquito bites and removing breeding sites.
- Preventing sexual transmission during pregnancy in areas where the virus circulates.
- No vaccine is available.
What it does to the embryo and fetus
- Severe microcephaly at birth or appearing after birth.
- Subcortical calcifications, ventriculomegaly and neuronal migration disorders on imaging.
- Macular and optic nerve lesions; vision and hearing problems.
- Arthrogryposis, hypertonia or spasticity, seizures and swallowing difficulty.
In the lab
- Prenatal ultrasound: microcephaly, calcifications and ventriculomegaly; these findings alone do not separate Zika from other congenital infections.
- Confirmation by laboratory testing for the virus in mother or newborn.
Test yourself
Think of the answer, then tap the question to see it.
In which period of pregnancy does Zika infection carry the highest risk of fetal damage?
The first trimester and early second trimester, while cortical neurons proliferate and migrate.
What are three features of congenital Zika syndrome?
Severe microcephaly with a collapsed skull, subcortical calcifications, macular lesions, arthrogryposis and early hypertonia.
What did Colombian surveillance show about the timing of the microcephaly peak?
It came about 24 weeks after the Zika peak in pregnant women, pointing to the first and early second trimester as the highest-risk period.
See it in 3D
The structures of Durgical's 3D anatomy where it is found.
Related
- TORCH infections: what each agent does to the embryo and fetus
- Microcephaly
- Brain vesicles: from three to five and what each becomes
- Coloboma, congenital cataract and congenital glaucoma
- Principles of teratology: critical periods, dose and genotype
- Prenatal diagnosis: ultrasound, serum screening, cell-free DNA, CVS, amniocentesis
Related conditions
- Zika virus infection
- Guillain-Barré syndrome
- Hearing loss (conductive and sensorineural, including sudden hearing loss)
- Neurogenic bladder
Microorganisms
Educational content on embryonic development; not a guide to prenatal diagnosis or to medicines in pregnancy and no substitute for a health professional's advice. No doses are given.
Sources: Congenital Zika Syndrome (CDC, NCBDDD (archived surveillance manual), 2020); Preliminary Report of Microcephaly Potentially Associated with Zika Virus Infection During Pregnancy — Colombia, January–November 2016 (CDC, Morbidity and Mortality Weekly Report, 2016); Vigilancia intensificada microcefalia y otros defectos congénitos del sistema nervioso central por virus Zika (Instituto Nacional de Salud (Colombia), 2017).
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Representative model, for educational purposes only.