Although there have only been two documented cases of sexual transmission of the Zika virus, and that is believed to be a relatively minor route of infection, public health agencies have been rolling out advice to the public on ways to reduce the potential risks.
You'll find the UK PHE's Advice here and the CDC's Interim advice here.
A week ago, the World Health Organization released Updated Information For Travelers Visting Zika Affected Countries, where they briefly addressed the potential for sexual transmission of the virus. Today they've published a 2 page PDF file with their interim recommendations, and their rationale for issuing them.
OverviewThis guidance has been developed to provide advice on the prevention of potential sexual transmission of Zika virus. The primary transmission route of Zika virus is via the Aedes mosquito. However, sexual transmission of Zika virus may also be possible, with limited evidence recorded in a few cases. This is of concern due to an association between Zika virus infection and potential complications, including microcephaly and Guillain-Barré syndrome.
The current evidence base on Zika virus remains extremely limited. This guidance will be reviewed and the recommendations updated as new evidence emerges.
From the PDF File:
2.2 Interim recommendations
Based on precautionary principles, WHO recommends that:
1. All patients (male and female) with Zika virus infection and their sexual partners (particularly pregnant women) should receive information about the potential risks of sexual transmission of Zika virus, contraceptive measures and safer sexual practices1, and should be provided with condoms when feasible. Women who have had unprotected sex and do not wish to become
pregnant because of concern with infection with Zika virus should also have ready access to emergency contraceptive services and counselling .
2. Sexual partners of pregnant women, living in or returning from areas where local transmission of Zika virus is known to occur, should use safer sexual practices or abstinence from sexual activity for the duration of the pregnancy.
3. As most Zika virus infections are asymptomatic:
a. Men and women living in areas where local transmission of Zika virus is known to occur should consider adopting safer sexual practices or abstaining from sexual activity.
b. Men and women returning from where local transmission of Zika virus is known to occur should adopt safer sexual practices or consider abstinence for at least four weeks after return.
4. Independently of considerations regarding Zika virus, WHO always recommends the use of safer sexual practices including correct and consistent use of condoms to prevent HIV, other sexually transmitted infections and unwanted pregnancies .
WHO does not recommend routine semen testing to detect Zika virus.