A 25 year-old primigravid woman at 23 weeks gestation by a 6 week sonogram presents for an initial prenatal visit. She reports an uneventful pregnancy thus far except for a short-lived febrile illness early in pregnancy that was associated with arthralgias, conjunctivitis, and a disseminated non-pruritic rash. Symptoms began after her husband returned from a business trip to Mexico. Her husband had a similar febrile illness upon return from his trip. An ultrasound of the fetal brain is shown below. In addition to the finding in the ultrasound, the fetal head measured 3.6 standard deviations below the mean.
The patient’s clinical history and subsequent ultrasound findings are most consistent with congenital Zika virus infection. Zika virus is spread to humans via a bite from the Aedes mosquito. The virus can also be contracted through sexual contact with an infected person. The virus can then spread from mother to fetus and cause devastating fetal anomalies. Providers should pay particular attention to the nervous system in a fetus with a possible maternal exposure to Zika virus. Ultrasound examination may show microcephaly, venticulomegaly, and intracranial calcifications, in addition to abnormalities within the corpus callosum, cerebrum, and cerebellum. Arthrogryposis has also been associated with fetal exposure to Zika virus. The best test to confirm congenital Zika virus infection is detection of viral nucleic acid in the amniotic fluid by RT-PCR.
Practice Advisory on Zika Virus. The American College of Obstetricians and Gynecologists. Updated August 3, 2016.