Ebola is spread through direct contact with an infected person's blood, including urine, saliva, sweat, feces, vomit, breast milk and semen, says the U.S. Centers for Disease Control and Prevention (CDC).
"Men who have recovered from Ebola virus disease should be aware that seminal fluid may be infectious for as long as three months after onset of symptoms," the World Health Organization said in a statement Friday.
"Because of the potential to transmit the virus sexually during this time, they should maintain good personal hygiene after masturbation, and either abstain from sex (including oral sex) for three months after onset of symptoms, or use condoms if abstinence is not possible."
Sexual transmission of Ebola virus disease has never been documented, the UN public health agency notes. Evidence is inconclusive on whether semen that tests positive for Ebola virus is infectious.
More than 15, 300 cases of Ebola have been reported up to the end of November 18, WHO says.
Almost all the cases and deaths have been in Guinea, Sierra Leone and Liberia — the three hardest-hit countries, which reported 600 new cases in the past week, the WHO said in its latest update.
Ebola is not spread through the air, by water or in general, by food, the CDC says.