Zika virus: preventing infection by sexual transmission

Zika virus and sexual transmission

The greatest likelihood of acquiring Zika virus infection is via the bite of an infected Aedes mosquito whilst travelling to a country or area with risk for Zika virus transmission. However, cases have also occurred through sexual transmission, mainly from a male to a female partner. Transmission from a female to a male sexual partner, and from a male to a male sexual partner has also been reported, whilst there is a theoretical risk of transmission from a female to a female sexual partner.

Sexual transmission can occur via vaginal sex, anal sex, oral sex and the sharing of sex toys. People infected with Zika virus can pass the virus through sex even when asymptomatic.

Potential consequences of Zika virus sexual transmission

Whether Zika virus is acquired from an infected mosquito or from sexual transmission, the clinical illness will be the same. Most people will be asymptomatic or will have a mild, self-limiting febrile illness.

The main concern of sexual transmission is the risk of acquisition in pregnancy as it may cause serious birth defects in the developing fetus. More information on this can be found here: Zika virus in pregnancy. It is therefore imperative that pregnant women avoid exposure to Zika virus including through sexual contact and couples take precautions to prevent a woman becoming pregnant during or shortly after having a possible Zika virus infection.

Barrier methods to prevent sexual transmission

There are recommended barrier methods to prevent sexual transmission of Zika virus from an individual who may have been exposed to Zika virus either as a traveller returning from a country or area with risk of Zika virus transmission or following previous unprotected sexual contact with a potentially infectious partner.

Barrier methods include:

• male or female condoms for penetrative sex (including sex toys)
• male or female condoms or dental dams for oral-genital or oral-anal sexual contact
• sex toys should not be shared
• to increase their effectiveness barrier methods should be used consistently and correctly, for the entire duration of sexual contact

Advice for pregnant women and their sexual partners

This advice is summarised in an algorithm which is available here.

Consistent use of barrier methods for vaginal, anal and oral sex during and after travel is advised to reduce the risk of sexual transmission which could result in the developing fetus becoming infected with Zika virus.

Barrier methods should be continued for the duration of the pregnancy and couples should use barrier methods during and after travel even in the absence of Zika virus symptoms.

Advice for couples considering pregnancy

This advice is summarised in an algorithm which is available here.

Consistent use of effective contraception and consideration of barrier methods for vaginal, anal and oral sex during and after travel is advised to reduce the risk of conception and sexual transmission which could result in the developing fetus becoming infected with Zika virus.

These measures should be maintained for the following time periods even in the absence of Zika virus symptoms:

• if both partners travelled, for 3 months after last possible Zika virus exposure ^{(note 1)}
• male traveller only, for 3 months after return or after last possible Zika virus exposure ^{(note 1)}
• female traveller only, for 2 months after last possible Zika virus exposure ^{(note 1)}

Note 1: Last possible Zika virus exposure is defined as the later of either the date of leaving a country or area with risk for Zika virus transmission, or the date on which last unprotected sexual contact with a potentially infectious partner took place.