The Centers for Disease Control and Prevention (CDC) has issued a warning to men who have visited countries where the Zika virus is prominent, should not have sex for six months after exposure even if they don’t show any signs of having contracted the virus.

The warning comes after initial warnings only stated those who showed symptoms of having caught the virus should refrain from sexual activity to lessen the chance of passing it on to a partner. This is particularly damaging if a couple is trying for a baby and could pass on the devastating effects onto the fetus.

It is thought the virus can remain active in the semen much longer than previously thought and without knowing it is being carried.

The virus, that is also carried by mosquitos, can cause a condition called microcephaly – a birth defect that causes a baby’s head develop abnormally small as well as brain damage.

“To date, Zika virus has been shown to be infectious from semen collected within three months after symptom onset. Given the limited data available and the potential for severe birth defects, CDC recommends men to wait six months before considering pregnancy,” reads the published report.

The updated guidelines include the following:

“Women and men who are planning to become pregnant in the near future should consider avoiding nonessential travel to areas with active Zika virus transmission.

“The amount of time to wait to attempt conception for couples in which the man has had possible Zika exposure but no Zika symptoms has increased from at least 8 weeks (previous guidance) to at least 6 months after last possible exposure (updated guidance).

“The amount of time to use a condom to protect against transmission of Zika virus infection or not have sex for men with possible Zika exposure but without symptoms has increased from at least 8 weeks to at least 6 months after last possible exposure.”