A 29-year-old pregnant woman from Canada, gravida 4 para 3, developed a low-grade fever and a generalized rash at 9-weeks gestation while visiting friends and relatives in Trinidad. Symptom onset occurred 6-weeks after arriving in Trinidad and all symptoms lasted for 4 days, followed by approximately one month of fever, myalgia, and retro-orbital headaches. Seven days after symptom onset she sought medical care in Trinidad with her 4-year-old child who was experiencing similar symptoms. Her blood tested negative in Trinidad by real-time reverse transcription polymerase chain reaction (PCR) for dengue and chikungunya viruses, but was positive for ZIKV. An ultrasonographic examination was not performed locally in Trinidad. One month after symptom onset she returned to Canada for further evaluation.
The patient was evaluated in our centre at 13 weeks 6 days gestation, which corresponded to one month post-symptom onset. Past medical history was significant for mild cerebral palsy and scoliosis. Her only medication was a prenatal multivitamin. She denied substance use during pregnancy. On examination, temperature was 38.1  C. Heart rate and blood pressure were normal. There was no conjunctivitis, lymphadenopathy, or organomegaly. Cardiorespiratory exam was normal. The previously mentioned diffuse rash had resolved.
Blood was drawn, and at 30 days post-symptom onset, ZIKV PCR, performed by Public Health Ontario Laboratory (PHOL), was positive at a cycle threshold (CT) of 31.85 using a commercial assay [RealStar  Zika Virus RT-PCR Kit (Altona Diagnostics, Hamburg, Germany). Urine ZIKV PCR was negative by the same assay. Dengue IgM and IgG were reactive, and chikungunya IgM and IgG were non-reactive. ZIKV IgM ELISA and plaque reduction neutralization test (PRNT) serology was performed at Canada's National Microbiology Laboratory (NML) as previously described. The ZIKV IgM ELISA was positive, however, the PRNT was inconclusive. Similar neutralization titres were demonstrated for both ZIKV and dengue virus (ZIKV titer 320, dengue virus titer 160) and were consistent with a previous exposure to a non-ZIKV flavivirus.
Fetal ultrasound performed at 14-weeks gestation revealed a single live intrauterine pregnancy with bilateral fluid collections in the fetal neck likely representing dilated jugular lymph sacs. The larger collection was 6-mm in size. Abnormal fetal intracranial anatomy was identified. There was asymmetry in the appearance of the lateral cerebral ventricles (Figure 1), the right ventricle appeared dilated especially in the frontal horn, and the left ventricle appeared small. The left choroid plexus was prominent in the frontal horn region and the third ventricle appeared slightly dilated. Head circumference was 14.5 weeks by size. No intracranial calcifications were seen.
Therapeutic termination of the pregnancy was performed by dilation and curettage at 15-weeks gestation. Initial molecular testing of fetal tissue was performed at PHOL. ZIKV RNA was detected in the umbilical cord (CT 31.70), placenta (CT 24.89), liver (CT 24.62), and fetal neural tissue (CT 17.42) using the RealStar  Zika Virus RT-PCR Kit. In addition, ZIKV sequence was confirmed in all fetal samples by RT-PCR and Sanger amplicon sequencing targeting 192 nucleotides of the ZIKV NS5 gene, based on a previously published protocol. All fetal tissue specimens were forwarded to NML and retested using the CDC-designed real-time RT-PCR assay based on the ZIKV strain responsible for the 2007 outbreak in Micronesia, targeting the ZIKV envelope (E) and premembrane (prM) genes. ZIKV RNA was again detected in umbilical cord, placenta, and fetal neural tissue specimens. Transmission electron microscopy was performed at PHOL on placenta, umbilical cord, and neural tissue specimens, however no viral particles were visualized. Fetal tissue karyotyping for aneuploidy was performed as per standard practice, and the result was a normal male chromosomal microarray pattern.