2803. Is Maternal Plasma Zika Virus Load Associated with Birth Outcomes and Maternal Disease Severity?

BACKGROUND: Adverse fetal outcomes and infant birth defects may develop following Zika virus (ZIKV) infection during pregnancy, especially if this occurs in the first trimester. The aim of this study was to assess the relationship between plasma ZIKV load at the time of acute symptoms and (1) the rate and severity of birth defects in neonates born to mothers who had presented with ZIKV infection during pregnancy, and (2) clinical severity of maternal ZIKV infection. METHODS: Within a cohort of pregnant women living in the French territories in the Americas and exposed to ZIKV during the 2016 outbreak, we analyzed the data of women who developed a symptomatic infection confirmed by a positive plasma ZIKV RT–PCR, using the RealStar Zika virus RT–PCR Kit (Altona Diagnostics, Hamburg, Germany). Plasma ZIKV load quantification was based on the number of cycle times (CT) at which ZIKV RNA was detected (lower CTs indicating a higher viral load). Variables indicating clinical severity of infection included the number of symptoms experienced and the severity of rash. Birth defects possibly linked to ZIKV infection were defined as microcephaly, brain imaging abnormalities, and central nervous system dysfunction. Multivariable logistic regression was used to examine whether potentially ZIKV-related abnormalities were linked to changes in CT, and multivariable linear regression was used to identify clinical correlates with CT value. RESULTS: Of the 277 live-born neonates who were born to mothers who met the selection criteria, 15 (5.4%) had abnormalities possibly linked to ZIKV infection. The median (IQR) ZIKV RT–PCR CT values were similar, with 31.4 (29.3–33.2) and 31.8 (30.0–33.0), in women delivering normal neonates and those delivering neonates with defects, respectively (OR: 1.04, P = 0.685). Plasma ZIKV load was lower with every day since first symptom onset, and higher with each additional symptom experienced, as indicated by changes in CT of 0.3 (95% CI: 0.2 ‒ 0.5, P < .001) and −0.3 (95% CI: −0.5 ‒ −0.1, P = 0.002) for each unit, respectively. CONCLUSION: No relationship was observed between plasma ZIKV load and abnormal pregnancy outcomes but higher plasma ZIKV load was associated with a more recent and severe maternal ZIKV infection. DISCLOSURES: All authors: No reported disclosures.