The US Centers for Disease Control and Prevention (CDC) has released updated interim guidelines for the prevention of sexual transmission of Zika virus from men who have been exposed to Zika to their female partners who are planning to conceive or want to prevent sexual transmission of Zika.
The new recommendations, published in the latest issue of the CDC’s Morbidity and Mortality Weekly Report
, suggest that men who have or have possibly been exposed to Zika wait at least 3 months after symptom onset or last possible Zika virus exposure before engaging in unprotected sex. Furthermore, the guidance suggests that couples who are not trying to conceive use condoms or abstain from sex for 3 months after last Zika exposure or symptom onset to minimize the risk of sexually transmitting the virus.
All other recommendations from the October 2016 guidelines remain unchanged (see below).
The updated guidance is based on the result of new findings on Zika virus infection that have come to light since the original guidelines were published. Investigators from the CDC conducted a literature review through PubMed
of relevant Zika research published after October 2016 and found 15 relevant publications from which data were analyzed to be reflected in the updated guidance.
The review revealed that among the results from the currently available studies, 1 study indicated that the longest period from symptom onset in an index case to potential sexual transmission to a partner was between 32 days and 41 days; most studies indicated much shorter intervals. The longest period after symptom onset at which replication of competent virus had been detected in semen was found to be 69 days. No other studies reported potentially infectious Zika virus in semen specimens obtained 40 days or longer after symptom onset.
Numerous publications reported on the detection of Zika virus RNA in semen; however, this does not necessarily indicate the presence of infectious virus at the time of sampling or correlate with the potential for sexual transmission.
The largest published cohort study involved 184 men with confirmed symptomatic Zika virus infection from whom a baseline specimen and several semen specimens were collected at 2-week intervals. Zika virus RNA declined during the 3 months after symptom onset. At more than 90 days, 7% or fewer participants had detectable Zika virus RNA. The estimated mean time to clearance of Zika virus from semen was 54 days.
In a Puerto Rican cohort study that followed 117 men, with 89 individuals providing semen specimens, the results showed that 11% (8 of 74 men with detectable Zika RNA) had RNA present in their semen more than 90 days after the onset of symptoms. Similar results were also observed in smaller cohort studies, according to the report.
Zika virus RNA has been detected in semen for as long as 370 days after symptom onset; however, detection for long periods like this was found to be rare. Limited data suggest the incidence of Zika virus RNA shedding in semen and its persistence are likely similar for symptomatic and asymptomatic men infected with Zika.
The findings from the literature review supported an update to the interim guidance, which had been based on the maximum duration of detection of Zika virus RNA in semen. The previous guidelines suggested that men wait 6 months following the onset of Zika symptoms or last possible Zika exposure before trying to conceive with their partner.
The following guidance issued in October 2016 remains unchanged:
- If only the female partner has traveled to an area with Zika virus and the couple is planning to conceive, the couple should abstain from sex or use condoms in the 2 months following the onset of symptoms or the last possible exposure to Zika.
- If 1 or both partners have ongoing exposure to Zika and plan to conceive, the couple should discuss pregnancy plans with a health care provider, including the possible effects of Zika virus infection on a baby and best methods to prevent infection. If either partner develops symptoms or tests positive for Zika virus infection, the couple should follow the appropriate guidance.
- If a male partner has possibly been exposed to Zika virus and his partner is pregnant, the couple should abstain from sex or use condoms for the remainder of the pregnancy.
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