Infants Born in New York City to Women with Zika Virus Exposure During Pregnancy, January 2016 – May 2017

Abstract

Background. Identifying pregnant women with possible Zika virus (ZIKV) infection facilitates timely identification and evaluation of infants potentially exposed to ZIKV in utero. Methods. Since 1/2016, the NYC DOHMH has been investigating cases of possible ZIKV infection in exposed pregnant women and their infants. Cases were identified by: (1) laboratory evidence of recent ZIKV infection in maternal and/or infant specimens, and (2) provider report of pre-/postnatal findings compatible with congenital ZIKV, regardless of maternal results. Laboratory evidence of recent ZIKV infection was defined as: positive result on ZIKV nucleic acid amplification testing (NAAT), or positive/equivocal result on ZIKV IgM with a serum plaque reduction neutralization testing (PRNT) titer ≥10 for ZIKV. ZIKV testing is recommended for all infants born to women with laboratory evidence of recent ZIKV infection. Results. From January 2016 to May 2017, DOHMH identified a total of 1084 cases of Zika virus infection among NYC residents. Median age was 33 years (range, 0-78 years). All cases were travel-associated, which includes cases due to sexual transmission. Most (>75%) cases reported travel to Caribbean. Among the cases were 405 (37%) pregnant women, 369 (91%) of whom have completed pregnancies. There have been 338 (92%) live infants and 31 (8%) pregnancy losses, including elective and spontaneous terminations. A total of 23 of 269 (9%) infants tested by ZIKV IgM had a positive result; one infant also had a positive urine NAAT result. Among these 23 infants, 6 (26%) had congenital Zika syndrome (CZS) and 1 (4%) had microcephaly without intracranial abnormalities. For 3 infants with CZS, results on maternal ZIKV NAAT and IgM testing were negative. Among 315 infants with negative or no ZIKV testing, 9 (3%) had microcephaly at birth. Conclusion. For NYC women with possible ZIKV infection during pregnancy, 9% of their infants had laboratory evidence of ZIKV. Among these infants, 30% had ≥1 finding consistent with congenital ZIKV infection. Negative maternal ZIKV results cannot rule out infection for women tested many months after ZIKV exposure. Sensitivity of ZIKV testing for infants is unknown. Collaboration between providers and public health departments is essential to ensure identification of infants with congenital ZIKV infection.