Study Supports Current Prevention Interventions for Zika Exposure

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Zika virus not detected in semen after 3 months from when symptoms began and unlikely to spread to others at 6 months.
Zika virus not detected in semen after 3 months from when symptoms began and unlikely to spread to others at 6 months.

SEATTLE — The current sexual prevention guidelines recommend that men use condoms or abstain from sex for 6 months after Zika virus exposure. Now, a new study presented at the 2017 Conference on Retroviruses and Opportunistic Infections (CROI 2017) has found that 95% of men cleared Zika RNA from semen over this time period.

“The results of this study demonstrated that in most cases Zika is no longer detected in semen after 3 months from when symptoms began and it is likely that the risk of spreading it to others is minimal at 6 months,” said Gabriela Paz-Bailey, MD, MSc, PhD, who is with the Behavioral Surveillance Team at the Centers For Disease Control and Prevention (CDC) in Atlanta, Georgia.

Dr Paz-Bailey and her team collected serum, saliva, urine, and semen/vaginal secretions weekly for the first month and at 2, 4, and 6 months following Zika virus exposure. The study included 150 participants and the interim analyses provide crucial information about time to clearance of Zika virus RNA in individuals with acute Zika virus infection.

The CDC and its partners conducted a study in Puerto Rico beginning in May 2016 investigating how frequently and for how long the Zika virus could be found in different human body fluids. “This study is unique in that 92% of participants were enrolled within 1 week after symptoms of Zika began, providing a clearer understanding of virus detection early in the course of infection. It is also the first study to examine multiple body fluids for the presence of Zika virus in an ongoing fashion,” said Dr Paz-Bailey.

She said the study found that Zika virus RNA was more likely to be found in serum than in urine. In serum, half of participants had detectable Zika virus RNA 14 days after the start of symptoms, with 5% still having detectable RNA at 54 days. “In urine specimens, half of the participants had Zika RNA at 8 days, with 5% still having detectable RNA at 39 days,” said Dr Paz-Bailey. In this study, Zika virus remained the longest in semen and half of participants had Zika virus RNA in their semen 1 month after the start of symptoms and about 5% still had detectable Zika virus RNA after 3 months.  

Other than this current study, there have been only 2 case reports of men whose semen still had detectable Zika for more than 6 months after symptoms began. Based on these findings, such late detection seems unusual. “It remains unclear whether those with detectable RNA pose an infection risk to partners at these time points. Zika virus particles were largely not detectable in saliva and vaginal fluids among participants in this study after 1 week,” said Dr Paz-Bailey.

She said in pregnant women who have recently traveled to an area with Zika, their healthcare provider can order a blood test to evaluate whether or not they currently are or were recently infected with Zika. In all other people who recently traveled to an area with Zika and had symptoms of an illness similar to Zika (fever, rash, joint pain, or red eyes), diagnostic testing can be ordered by a clinician. 

“Understanding how often and for how long evidence of Zika virus can be found in different body fluids can improve testing methods and could have implications for prevention and education efforts. Our findings support current sexual transmission recommendations,” Dr Paz-Bailey told Infectious Disease Advisor

The CDC recommends that men with possible Zika virus exposure use condoms or not have sex for at least 6 months from the beginning of symptoms or from last exposure. It recommends that women with possible Zika virus exposure wait at least 8 weeks from beginning of symptoms or the most recent exposure before trying to become pregnant. The CDC recommends that people with potential exposure to Zika virus avoid donating blood for at least 120 days.

Reference

Paz-Bailey G, Rosenberg E, Doyle K, et al. Zika virus persistence in body fluids. Presented at: CROI 2017. Seattle, WA; February 13-16, 2017. Abstract 1055LB.

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