Ebola Virus Genetic Material Can Remain in Semen for 18 Months, New Study Shows

— -- Genetic material from the deadly Ebola virus was found in survivors more than a year and a half after being infected, according to a report published today in the medical journal The Lancet.

RNA from the Ebola virus persisted in 9 percent of the patients studied, according to researchers from the Liberia Ministry of Health and U.S. Centers of Disease Control and Prevention who collaborated on the report.

The new findings could change the recommendations for male survivors for both the CDC and the World Health Organization. Currently the WHO recommends an Ebola survivor use barrier contraception or abstain from sex for 12 months if they have not had their semen tested for the virus.

“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,” CDC Director Dr. Tom Frieden said in a statement today. “It also shows how investments in public health capacity can save lives.”

More than 450 men from Liberia were screened in the months after they contracted the disease and officials found that 24 men had evidence of Ebola in their semen 12 months after they had recovered from the virus, according to the new report. One of the patients had virus particles in his semen 565 days after his illness. Previously, the longest time Ebola was documented to be present in semen was 6 months.

Researchers found that older men over the age of 40 were more likely to have viral genetic materials found in semen 90 days after they left treatment centers.

In at least one case, a woman likely contracted Ebola through unprotected sexual contact with an Ebola survivor, according to a CDC report published in May 2015. In that case, the male Ebola survivor had finished treatment for Ebola in October 2014 and then had sexual intercourse with the patient in March of the following year.

"It is not known how long Ebola might be found in the semen of male Ebola survivors," according to the CDC website. "The time it takes for Ebola to leave the semen is different for each man. Based on the results from limited studies conducted to date, it appears that the amount of virus decreases over time and eventually leaves the semen."

Dr. Kathryn Horton, a resident in the ABC News Medical Unit, contributed to this report.