From the Journals

Zika virus: Sexual contact risk may be limited to short window



Shedding of infectious Zika virus in the semen of symptomatic infected men appears to be uncommon and limited to the first few weeks after onset of illness, according to results of a recent prospective study.

Out of all semen samples with detectable Zika virus RNA, the only ones with infectious virus were those that had been obtained within 30 days of illness onset, study authors reported in the New England Journal of Medicine.

“The shedding of infectious Zika virus that could be cultured was rare, short-lived, and limited to the few samples with at least 7.0 log10 Zika virus RNA copies per milliliter of semen,” wrote first author Paul S. Mead, MD, MPH, of the National Center for Emerging and Zoonotic Infectious Diseases, Fort Collins, Colo., and his coauthors.

Sexual transmission of Zika virus, first documented in 2011, has now been reported in at least 13 countries, Dr. Mead and his colleagues wrote.

Usually, the cases have involved transmission from a symptomatic man to a woman, they added.

Previously, some investigators had proposed that sexual transmission of Zika virus could pose a greater risk of fetal infection than could mosquito-borne transmission, Dr. Mead and colleagues noted in their report. “If so, the interruption of sexual transmission could play a critical role in preventing the serious complications that have been associated with fetal infection,” they wrote.

To investigate further, Dr. Mead and his colleagues conducted a prospective study of men with symptomatic Zika virus infection. They collected 1,327 semen samples from 184 men and 1,038 urine samples from 183 men, according to the report.


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