The study, published in the Lancet Global Affairs, involved 429 men seen between July 2015 and May 2016 who were part of the Liberian government's Men's Health Screening Program (MHSP), the first national semen testing program for Ebola virus.
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In one case, Ebola was detected at least 565 days after a man recovered from his illness.
As part of Liberia's monitoring program, male survivors aged 15 and older can enroll for monthly tests of their semen.
"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," Dr. Thomas Frieden, director of the U.S. Centers for Disease Control and Prevention, which is collaborating with the ministry.
Other partners include the World Health Organization, and the Academic Consortium Combating Ebola in Liberia.
Semen samples in the study were tested for genetic fragments known as the viral RNA, but the tests could not tell if the virus was capable of spreading disease.
Sexual contact with an Ebola survivor in March 2015 resulted in the infection and eventual death of a woman from Monrovia, even after Liberia had been declared free of Ebola. Tests of the man's semen showed the presence of Ebola virus 199 days after he first became ill.
The World Health Organization advises that all male Ebola survivors should be tested three months after the onset of symptoms and then monthly until they know they have no risk of passing on the virus.