A 24-year-old woman, gravida 1 para 0, at 26 weeks gestation comes to the emergency department due to abdominal cramping and vaginal bleeding. She recently emigrated from Bolivia and reports no prior medical problems. The patient's only medication is a daily multivitamin. Immunization status is unknown. The patient spontaneously delivers a stillborn fetus with multiple congenital malformations. Fetal autopsy reveals microcephaly with thin cerebral cortices, ventriculomegaly, and subcortical calcifications. Viral RNA of a neurotropic virus is detected in body fluids of the mother and the fetus. Transplacental transmission of this virus causes apoptosis of neural progenitor cells in the developing fetus, leading to disruption of neuronal proliferation, migration, and differentiation. Which of the following viruses most likely caused this patient's in utero infection?
Congenital Zika syndrome | |
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Zika virus is a single-stranded RNA virus belonging to the Flavivirus genus. Transmission occurs primarily via an Aedes mosquito bite, but infected patients can also spread the virus via genital secretions. The neurotropic virus can cross the placenta and infect and destroy fetal neural progenitor cells, causing congenital Zika syndrome and possible fetal demise. Fetal brain development is impaired due to disruption of normal proliferation, migration, and differentiation of neurons.
Classic findings in affected newborns include microcephaly with facial features out of proportion to head size, arthrogryposis (contractures), seizures, hypertonia, and ocular abnormalities. Loss of brain mass (eg, cortical thinning, ventriculomegaly) as well as subcortical calcifications are typically present. Diagnosis is confirmed by detection of Zika RNA (real-time reverse transcriptase PCR) in serum, urine, or cerebrospinal fluid.
The mainstay of treatment for surviving infants is supportive care with management of feeding difficulties, hydrocephalus, and seizures. Pregnant women should be counseled to avoid traveling to areas with ongoing Zika transmission (eg, South and Central America, Asia, Africa, Mexico, the Caribbean).
(Choices A, B, and E) Cytomegalovirus (CMV), herpes simplex virus (HSV), and varicella zoster virus (VZV) are double-stranded DNA viruses that can be transmitted in utero and cause CNS abnormalities in the fetus. Typical CMV findings include hearing loss, chorioretinitis, jaundice, and periventricular calcifications. When transmitted in utero, HSV and VZV can cause diffuse cutaneous lesions and severe brain destruction; hypoplasia of the limbs and eyes is also commonly seen with fetal VZV infection.
(Choice C) Parvovirus B19 is a single-stranded DNA virus that infects and destroys erythroid progenitor cells and can result in fetal hydrops when the infection is contracted during pregnancy.
(Choice D) Rubella virus is a single-stranded RNA virus that typically presents with cardiac defects, hearing loss, and cataracts.
Educational objective:
Zika virus is a single-stranded RNA virus that infects fetal neural progenitor cells, causing severe congenital malformations (eg, microcephaly, arthrogryposis), cerebral cortical thinning, and possible fetal demise.