See how long Zika lasts in semen and other bodily fluids

Traces of Zika virus typically linger in semen no longer than three months after symptoms show up, a new study on the virus’ staying power in bodily fluids reveals.

Medical epidemiologist Gabriela Paz-Bailey of the U.S. Centers for Disease Control and Prevention and colleagues analyzed the bodily fluids — including blood, urine and saliva — of 150 people infected with Zika. In 95 percent of participants, Zika RNA was no longer detectable in urine after 39 days, and in blood after 54 days, researchers report February 14 in the New England Journal of Medicine. (People infected with dengue virus, in contrast, typically clear virus from the blood within 10 days, the authors note.)

Although the CDC recommends that men exposed to Zika wait at least six months before having sex without condoms, researchers found that, for most men in the study, Zika RNA disappeared from semen by 81 days.

Few people had traces of RNA in the saliva or in vaginal secretions. Most Zika infections transmitted sexually have been from men to women, but scientists have reported at least one female-to-male case.

Bodily fluid breakdown

In 95 percent of people tested, Zika RNA is cleared from the blood by 54 days after symptoms begin, and urine by 39 days. In 95 percent of men tested, Zika RNA disappears from semen by 81 days. Few people in the study had detectible levels of Zika RNA in saliva or vaginal secretions.

Source: G. Paz-Bailey et al/NEJM 2017