Traces of Ebola can stay in semen for over a year and a half after a patient's recovery, a period longer than originally believed, according to a study published in Lancet Global Health. The report includes data from 429 men seen between July 2015 and May 2016 as part of the Liberian government's Men's Health Screening Program, the first national initiative to test semen for the virus.

"Before this outbreak, scientists believed that Ebola virus could be found in semen for three months after recovery," said Dr. Moses Soka, coordinator of the Ebola Virus Disease Survivor Clinical Care at Liberia's Health Ministry. "With this study, we now know that virus may persist for a year or longer."

The World Health Organization advises that male Ebola survivors get tested three months after the onset of symptoms and then follow up monthly until they know that they have no risk of passing on the virus. Sexual contact with a survivor in March resulted in the infection and eventual death of a woman from Monrovia, even after researchers had declared Liberia free of Ebola - following 42 days without a new transmission after the final known patient had recovered. Tests of the man's semen showed the presence of Ebola virus 199 days after he first became ill.

For the study, scientists tested semen samples for genetic fragments known as the viral RNA, but the tests did not determine whether that could spread the disease. However, in one case, doctors detected Ebola at least 565 days after a man had recovered from his illness.

Of the 429 participants, 38 men - or 9 percent - tested positive during the study period. Within this group, 24 men (63 percent) had semen samples that tested positive for Ebola fragments a year after they had recovered from the disease.

'Preventing flare-ups'

In Liberia, male survivors aged 15 and older can enroll for monthly tests of their semen. Participants also get counseling on safe sex and condoms at each visit.

"This program provides important insights into how long Ebola remains in semen, a key component to preventing flare-ups of the disease and protecting survivors and their loved ones," US Centers for Disease Control and Prevention Director Thomas Frieden said. The CDC has worked with the ministry along with the the World Health Organization and the Academic Consortium Combating Ebola in Liberia.

Along with Sierra Leone and Guinea, Liberia was one of the countries hit hardest by the 2014-15 mass outbreak of Ebola. More than 11,000 people died in the countries combined.

mkg/gsw (EFE, Reuters)