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Zika virus detected in maternal serum longer than previously reported

Zika virus RNA has been detected in the serum of five pregnant women far beyond the previously estimated timeframe, with one case remaining detectable for up to 53 days following exposure, according to data published in Obstetrics & Gynecology.

“The duration of Zika virus RNA in serum is considered brief; the mean time from infection to viral clearance is reported as approximately 10 days,” Dana Meaney-Delman, MD, MPH, of the CDC National Center for Emerging and Zoonotic Infectious Diseases, and colleagues wrote. “However, data on Zika virus RNA detection in individuals through repeated sampling are limited, and the duration of viral detection has not been studied systematically in pregnant women.”

To summarize the clinical and laboratory characteristics of pregnant women with prolonged Zika virus detection, the researchers reviewed data reported to the U.S. Zika Pregnancy Registry. The registry was established by the CDC in collaboration with state, tribal, territorial and local health departments to collect information about pregnant women with any laboratory evidence compatible with possible Zika infection, or a recent flavivirus infection.

Prolonged detection was defined as Zika virus RNA reported in serum by real-time reverse transcription-polymerase chain reaction 14 or more days after symptom onset. For asymptomatic women, prolonged detection was defined as Zika RNA reported in serum 21 or more days after the last possible exposure to the virus.

According to the researchers, Zika RNA was detected in serum in four symptomatic pregnant women up to 46 days after onset. In the fifth case, in which the patient was asymptomatic, Zika RNA was detected for up to 53 days after exposure. All five women had travelled to or lived in one or more of the following countries: Colombia, the Dominican Republic, El Salvador, Guyana, Honduras and Mexico. One pregnancy had evidence of fetal Zika virus infection, confirmed by histopathologic examination of fetal tissue, and was terminated. Among the four other pregnancies, as of July 21, 2016, one was ongoing and the other three resulted in live births of apparently healthy neonates with no reported abnormalities.

“This report adds to the existing evidence that Zika virus RNA in serum may be detected longer than previously expected, and observation now reported among at least eight pregnant women,” Meaney-Delman and colleagues wrote. “These data also suggest that Zika virus RNA might be detectable for prolonged periods in some asymptomatic pregnant women.” – by Jason Laday

Disclosure: The researchers report no relevant financial disclosures.