Live Ebola virus can persist in the semen of some survivors for at least nine months, according to preliminary results of a study published on Wednesday, 14 October.

Previously, Ebola has been detected in the semen of men after their recovery but little information is available about the duration of its persistence in that body fluid, according to Xinhua.

In the new study, 93 men over the age of 18 from Freetown, Sierra Leone, provided semen samples that were tested to detect the presence of Ebola virus genetic material.

For men who were tested in the first three months after their illness began, all were positive, said the study, which was published in the US New England Journal of Medicine.

More than half of men who were tested between four to six months after their illness began were positive, while one quarter of those tested between seven to nine months after their illness began also tested positive.

Why some study participants had cleared the fragments of Ebola virus from semen earlier than others remains unclear. The US Centre for Disease Control and Prevention said it is conducting further tests of the samples to determine if the virus is live and potentially infectious.

"These results come at a critically important time, reminding us that while Ebola case numbers continue to plummet, Ebola survivors and their families continue to struggle with the effects of the disease," Bruce Aylward, WHO director general's special representative on the Ebola response, said in a statement.

"This study provides further evidence that survivors need continued, substantial support for the next six to 12 months to meet these challenges and to ensure their partners are not exposed to potential virus."

According to the study, until a male Ebola survivor's semen has twice tested negative, he should abstain from all types of sex or use condoms when engaging in sexual activity.

The study was jointly conducted by the Sierra Leone ministry of health and sanitation, Sierra Leone ministry of defence, the World Health Organisation and the US Centres for Disease Control and Prevention.