Maternal Zika Virus Disease Severity, Virus Load, Prior Dengue Antibodies, and Their Relationship to Birth Outcomes

Abstract

Background: Congenital Zika virus (ZIKV) syndrome is a newly identified condition resulting from infection during pregnancy. We analyzed outcome data from a mother-infant cohort in Rio de Janeiro in order to assess whether clinical severity of maternal ZIKV infection was associated with maternal virus load, prior dengue antibodies, or abnormal pregnancy/infant outcomes.

Methods: A clinical severity assessment tool was developed based on duration of fever, severity of rash, multisystem involvement, and duration of symptoms during ZIKV infection. ZIKV-RNA load was quantified by polymerase chain reaction (PCR) cycles in blood/ urine. Dengue immunoglobulin G (IgG) antibodies were measured at baseline. Adverse outcomes were defined as fetal loss or a live infant with grossly abnormal clinical or brain imaging findings. Regression models were used to study potential associations.

Results: 131 ZIKV-PCR positive pregnant women were scored for clinical disease severity, 6 (4.6%) had mild disease, 98 (74.8%) had moderate disease, and 27 (20.6%) severe manifestations of ZIKV infection. There were 58 (46.4%) abnormal outcomes with 9 fetal losses (7.2%) in 125 pregnancies. No associations were found between: disease severity and abnormal outcomes (P = .961; odds ratio [OR]: 1.00; 95% confidence interval [CI]: 0.796-1.270); disease severity and viral load (P = .994); viral load and adverse outcomes (P = .667; OR: 1.02; 95% CI: 0.922-1.135); or existence of prior dengue antibodies (88% subjects) with severity score, ZIKV-RNA load or adverse outcomes (P = .667; OR: 0.78; 95% CI: 0.255-2.397).

Conclusions: Congenital ZIKV syndrome does not appear to be associated with maternal disease severity, ZIKV-RNA load at time of infection or existence of prior dengue antibodies.

Keywords: ZIKV; Zika; congenital; dengue; pregnancy.

© The Author 2017. Published by Oxford University Press for the Infectious Diseases Society of America. All rights reserved. For permissions, e-mail: journals.permissions@oup.com.

Figures

Figure 1.

Distribution of Zika virus infection clinical severity scores. Reference lines indicate severity grades; mild presentation score = 4, moderate presentation score = 5–8, severe presentation score = 9–12.

Figure 2.

A, ZIKV PCR cycles by severity grade of clinical presentation. Abbreviation: B, ZIKV PCR cycles according to pregnancy outcomes. Abbreviation: PCR, polymerase chain reaction.

Figure 3.

Pregnancy and infant outcomes according to maternal Zika virus disease severity.