Characteristics, risk factors, and outcomes related to Zika virus infection during pregnancy in Northeastern Thailand: A prospective pregnancy cohort study, 2018-2020

PLoS Negl Trop Dis. 2024 May 17;18(5):e0012176. doi: 10.1371/journal.pntd.0012176. eCollection 2024 May.

Abstract

Background: In response to the 2015-2016 Zika virus (ZIKV) outbreak and the causal relationship established between maternal ZIKV infection and adverse infant outcomes, we conducted a cohort study to estimate the incidence of ZIKV infection in pregnancy and assess its impacts in women and infants.

Methodology/principal findings: From May 2018-January 2020, we prospectively followed pregnant women recruited from 134 participating hospitals in two non-adjacent provinces in northeastern Thailand. We collected demographic, clinical, and epidemiologic data and blood and urine at routine antenatal care visits until delivery. ZIKV infections were confirmed by real-time reverse transcriptase polymerase chain reaction (rRT-PCR). Specimens with confirmed ZIKV underwent whole genome sequencing. Among 3,312 women enrolled, 12 (0.36%) had ZIKV infections, of which two (17%) were detected at enrollment. Ten (83%, 3 in 2nd and 7 in 3rd trimester) ZIKV infections were detected during study follow-up, resulting in an infection rate of 0.15 per 1,000 person-weeks (95% CI: 0.07-0.28). The majority (11/12, 91.7%) of infections occurred in one province. Persistent ZIKV viremia (42 days) was found in only one woman. Six women with confirmed ZIKV infections were asymptomatic until delivery. Sequencing of 8 ZIKV isolates revealed all were of Asian lineage. All 12 ZIKV infected women gave birth to live, full-term infants; the only observed adverse birth outcome was low birth weight in one (8%) infant. Pregnancies in 3,300 ZIKV-rRT-PCR-negative women were complicated by 101 (3%) fetal deaths, of which 67 (66%) had miscarriages and 34 (34%) had stillbirths. There were no differences between adverse fetal or birth outcomes of live infants born to ZIKV-rRT-PCR-positive mothers compared to live infants born to ZIKV-rRT-PCR-negative mothers.

Conclusions/significance: Confirmed ZIKV infections occurred infrequently in this large pregnancy cohort and observed adverse maternal and birth outcomes did not differ between mothers with and without confirmed infections.

MeSH terms

  • Adult
  • Female
  • Humans
  • Incidence
  • Infant, Newborn
  • Pregnancy
  • Pregnancy Complications, Infectious* / epidemiology
  • Pregnancy Complications, Infectious* / virology
  • Pregnancy Outcome
  • Prospective Studies
  • Risk Factors
  • Thailand / epidemiology
  • Young Adult
  • Zika Virus Infection* / epidemiology
  • Zika Virus* / genetics
  • Zika Virus* / isolation & purification

Grants and funding

This project received funding provided by the U.S. government through the Office of Infectious Diseases, Bureau for Global Health, U.S. Agency for International Development, from the Zika Emergency Fund under the terms of an Interagency Agreement with the U.S. Centers for Disease Control and Prevention (CoAg/IAA 16CGH1613816), and also from the U.S. Centers for Disease Control and Prevention (CoAg/ 1U01GH002084). Subsequently, the Thailand MOPH – U.S. CDC collaboration unit utilized this funding to provide financial support for this study. The funders played no role in the design of the study, data collection and analysis, decision to publish, or preparation of the manuscript. The following authors received compensation from the project for their part-time hours dedicated to research activities: JW, SU, AV, PD, KS, CW, PS, BP, and PS. The following authors received partial support for their salaries: ST, PT, PS, BS, PAM, JRM, IS, PS, PK, and EB. DJ, the Project Coordinator at one of provincial sites, received a full salary from the project.