Zika Virus May Persist in Semen Less Than 6 Months

Zika may not survive in semen as long as researchers previously thought. Although previous reports indicated that the virus may persist in semen for up to 188 days, a new study, recently published in the New England Journal of Medicine, is disputing that finding, instead providing evidence that the Zika virus only lasts in semen for about a month.

In the new study, researchers from the Military Center for Epidemiology and Public Health in Marseille, France looked at semen and blood samples from 12 men in French Guiana who were infected with the Zika virus. The results of the study indicated that, “one man excreted Zika virus in his semen for at least 3 days. And, 7 had Zika-laced semen for at least a month. The maximum duration of detectable Zika in semen in the study was 45 days,” according to a press release. In addition, the researchers discovered that the virus is able to replicate in the testicles and semen-producing glands. This was determined because the viral load detected in the men’s blood was significantly different than in their semen.

Study author Franck de Laval, MD, and his colleagues wrote that, “these data suggest that not all men who are symptomatically infected with Zika virus will have Zika virus RNA detectable in semen. [However,] more data are needed to better inform public health recommendations.”

The current Centers for Disease Control and Prevention (CDC) recommendations state that men with pregnant partners should use condoms or abstain from sex for the duration of the pregnancy. For men with partners who are not pregnant, but are planning to become pregnant, they should wait at least 6 months post exposure to the Zika virus or visiting Zika-endemic areas before trying to conceive. In the press release, Daniel Caplivski, MD, director of the Travel Medicine Program and associate professor for the division of infectious diseases at the Icahn School of Medicine at Mount Sinai in New York City, New York stated that the CDC guidelines are unlikely to change after this report. “Unfortunately, the fundamental recommendations of public health experts regarding delaying pregnancy after Zika virus infection or exposure are unlikely to change, given the degree of uncertainty that remains from other studies in which the genetic material of the virus was detectable for longer periods of time,” he said.

Even for men who have partners who are not planning to become pregnant, it is important that they practice safe-sex, or abstain completely for 6 months post-exposure. “Because it is unclear which men will have longer persistence, it is important for Zika-infected/exposed men to practice safe sexual practices for 6 months post-infection to avoid transmission of the virus,” Amesh Adalja, MD, senior associate with the Johns Hopkins Center for Health Security, in Baltimore, Maryland stated.

Jill Rabin, MD, a women’s health specialist highlighted in the press release that although it is good news that the virus may not persist in semen as previously thought, “…we need to have a larger sample size and follow people for a longer period of time. Because we don't have enough data and we don't have enough people, we can't really say what is the time period needed to be free of infection.”