Scientists have found Ebola stays in the semen of male survivors for up to nine months after recovery - much longer than previously thought.
Previous advice to survivors was to abstain from sex, or use a condom for three months, after which it was thought the virus would be out of the system.
Ebola was detected in the semen of almost two thirds of the latest study’s participants after six months, and in more than a quarter of those after nine months.
The research, published in the New England Journal of Medicine, shows that the virus could be passed on and result in new cases after the outbreak is over.
Around half of the 16,000 survivors of Ebola in Sierra Leone, Guinea and Liberia are male.
Researchers said: “There are thousands of survivors of EVD (Ebola virus disease) in western Africa, and many are sexually active men. Sexual transmission of the Ebola virus could possibly result in new outbreaks several weeks or months after all known chains of transmission in the region have stopped.”
They said more research needs to be done into the potential for the virus to remain in other bodily fluids, including in women.
“Even though there have been only rare cases of EVD linked to sexual transmission, research is needed to investigate whether infectious virus may be present in vaginal fluid or other body fluids after recovery, and the testing of additional body fluids in both male and female survivors is planned,” the study said.
Researchers called for programmes around semen testing and counselling to educate survivors and reduce the risk of the virus being passed on through sex.
They said: “Such programmes would help men and women understand their individual risk and take appropriate measures to protect their sexual partners, specifically in regard to condom use and disposal, and could provide links to care and counselling programmes for survivors.
“Because semen-testing programmes are not yet universally available, outreach activities are needed to provide education regarding recommendations and risks to survivor communities and sexual partners of survivors in a way that does not further stigmatise the community of survivors of EVD.”