Mead PS, et al. - In this prospective study, researchers determined the frequency and duration of Zika virus (ZIKV) shedding in semen and urine and investigated risk factors for prolonged shedding in these fluids among men with symptomatic ZIKV infection. They noted the common presence of ZIKV RNA in the semen of men with symptomatic ZIKV infection. In some men, it persisted for more than 6 months. On the other hand, shedding of infectious ZIKV seemed to be much less common and was limited to the first few weeks after illness onset.

Methods

• Researchers obtained specimens twice per month for 6 months after illness onset.
• They tested the specimens by real-time reverse-transcriptase–polymerase-chain-reaction (RT-PCR) assay for ZIKV RNA and by Vero cell culture and plaque assay for infectious ZIKV.

Results

• Researchers obtained a total of 1,327 semen samples from 184 men and 1,038 urine samples from 183 men 14 to 304 days after illness onset.
• They detected ZIKV RNA in the urine of 7 men (4%) and in the semen of 60 (33%), including in semen samples from 22 of 36 men (61%) who were tested within 30 days after illness onset.
• During the 3 months after illness onset, ZIKV RNA shedding in semen decreased substantially but it continued for 281 days in 1 man (1%).
• Prolonged RNA shedding was noted to have an independent association with factors including older age, less frequent ejaculation, and the presence of certain symptoms at the time of initial illness.
• In this study, infectious ZIKV was isolated from 3 of 78 semen samples with detectable ZIKV RNA, all obtained within 30 days after illness onset and all with at least 7.0 log₁₀ ZIKV RNA copies per milliliter of semen.