Infectious Zika virus was isolated from just 3 out of the 78 semen samples with detectable Zika virus RNA that were tested by culture, investigators said. Notably, all 3 of the cases were among the 19 of those samples obtained within 30 days of illness onset, they reported.
Detection of Zika virus RNA in urine was rare, occurring in only 7 men (4%), possibly because of the timing of the first specimen collection, according to investigators. They said previous studies suggest a rapid decline in Zika virus shedding in urine during the first few weeks after onset of illness.
Important questions remain regarding sexual transmission of Zika virus, such as whether maternal infection through sex poses similar risks to the fetus as compared with maternal infection via mosquito bite, Dr. Mead and his coauthors said in the report.
“A better understanding of these issues is needed to guide the development of effective prevention strategies,” they wrote.
The study was supported by the Centers for Disease Control and Prevention. Dr. Mead and his coauthors reported they had no disclosures related to the study.