The World Health Organisation (WHO) has urged Ebola survivors to practise safe sex following the discovery of traces of the virus in the semen of an Ebola survivors almost 6 months after his revocery.

BBC reports that this is some 90 days later than previously documented and while it's unclear whether Ebola can still be spread at this point, officials have launched further investigations to evaluate the risks.

Although there's been no proven cases of Ebola being transmitted through sexual contact with survivors during this or previous outbreaks, the body says this recent case prompts experts to strengthen their advice.

According to Dr Nathalie Broutet, a medical officer at the World Health Organization:

"The patient is the first we have seen where there is a trace of virus present in semen beyond three months. This made us change our recommendations to go beyond three months."

Thus, the new advice is:

"For greater security and prevention of other sexually transmitted infections, Ebola survivors should consider correct and consistent use of condoms for all sexual acts beyond three months until more information is available."

Thisbuilds on previous guidance suggesting abstinence or safe sex up to 90 days after symptoms first develop.

Scientists are reportedly planning to send the sample to the Centres for Disease Control in the United States to see if the traces of Ebola they found are active and capable of being spread while studies in Sierra Leone and Guinea  will be done to offer male survivors further checks.

According to the WHO, there is no current evidence to suggest that active Ebola virus is present in vaginal fluids once someone has recovered.

Meanwhile, experts have emphasised that people who have recovered from Ebola do not pose any risks to the general public and should not be isolated.