Zika virus RNA detected in serum beyond previously estimated time frame




Zika virus RNA was detected in the serum of five pregnant women beyond previously estimated time frames, according to a new case series study.

“This report adds to the existing evidence that Zika virus RNA in serum may be detected longer than previously expected, an observation now reported among at least eight pregnant women,” reported Dr. Dana Meaney-Delman of the Centers for Disease Control & Prevention, and her colleagues wrote. (Obstet Gynecol. 2016. doi: 10.1097/AOG.0000000000001625).

©Felipe Caparrós Cruz/Thinkstock

Five pregnant women who had traveled to or lived in one or more countries with active Zika virus transmission and had prolonged detection of Zika virus RNA in serum were reported to the U.S. Zika Pregnancy Registry, an enhanced surveillance initiative developed by the CDC to collect information on maternal exposure history, clinical presentation, laboratory testing, prenatal imaging, pregnancy screening and complications, fetal and neonatal outcomes, and infant development through the first year of life.

Prolonged detection was defined as the presence of Zika virus RNA detected in serum by real-time reverse transcription-polymerase chain reaction at 14 or more days after symptom onset for symptomatic pregnant women or 21 or more days after last possible exposure to Zika virus for asymptomatic pregnant women. A previous study reported a mean Zika viral RNA duration of 9.9 days, with 14 days being the longest duration of Zika virus RNA detection in a nonpregnant person.

Among the four symptomatic pregnant women, Zika virus RNA was detected in the serum at 17, 23, 44, and 46 days following symptom onset. In the one asymptomatic pregnant woman, Zika virus RNA was detected in serum at 53 days after her travel from an area with active Zika transmission.

Among the five pregnancies, one is ongoing, one was aborted and the fetus tested positive for fetal Zika virus infection, and three resulted in live births of healthy neonates with no reported abnormalities.

“Several questions remain regarding the findings of prolonged detection of Zika virus RNA. Most notably, the duration of Zika virus RNA in serum requires further investigation to determine whether there is a correlation between prolonged viral RNA detection and the presence of infectious virus,” the researchers wrote.

Read the study results here.

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