The patient is a 33-year-old woman who visited Mexico, Guatemala, and Belize with her husband in November. She was in her 11th week of pregnancy and remembered being bitten by mosquitoes in Guatemala. The day after her arrival home in the US, she developed ocular pain, myalgia, and a mild fever that lasted five days. She broke out in a rash on the second day. Meanwhile, her husband also developed symptoms. A month later she tested positive for IgG antibodies and negative for IgM antibodies to dengue and positive for both IgG and IgM antibodies to Zika virus. She was negative for antibodies to chikungunya virus.
Ultrasonography at one, four, and six weeks after infection showed no intracranial calcifications or microcephaly. Zika virus was detected by RT-PCR and it was identified as a Central American strain by sequencing. The IgM for Zika was 1:2,560 on the plaque-reduction neutralization test (PRNT).
Between the 16th and 20th weeks of her pregnancy, the fetal head circumference dropped to the 24th percentile. At 19 weeks of gestation, the ultrasound showed abnormal intracranial anatomy. The fetal MRI, performed at 20 weeks gestation, showed various changes in the fetus's brain with diffuse atrophy of the cerebral mantle, shortened corpus callosum, and loss of the frontal and parietal lobes of the cerebrum.
The patient chose to terminate the pregnancy at 21 weeks. The fetus was examined and high viral loads of Zika virus were found in the brain. Abundant apoptotic neurons were seen in the parietal cortex. Viral cultures of the brain were positive for Zika virus.
