Ebola Resource Center

Ebola Resource Center

October 14, 2015
3 min read

Ebola virus perseveres in semen at least 9 months after infection

You've successfully added to your alerts. You will receive an email when new content is published.

Click Here to Manage Email Alerts

We were unable to process your request. Please try again later. If you continue to have this issue please contact customerservice@slackinc.com.

Ebola virus RNA was detected in semen samples at least 9 months after the onset of illness, according to a preliminary report conducted by WHO, the CDC and the Sierra Leone Ministry of Health and Sanitation.

“Ebola survivors face an increasing number of recognized health complications,” CDC Director Thomas R. Frieden, MD, MPH, said in a press release. “This study provides important new information about the persistence of Ebola virus in semen and helps us make recommendations to survivors and their loved ones to help them stay healthy.”

Thomas R. Frieden

Thomas R. Frieden

Earlier recommendations advised Ebola virus disease survivors to practice abstinence or use condoms at least 3 months after recovery, researchers wrote in the New England Journal of Medicine. In March, however, an EVD survivor was found to have Ebola virus RNA in his semen 199 days after the onset of symptoms.

During an investigation by Suzanne E. Mate, PhD, from the Center for Genome Sciences, and colleagues, the researchers concluded that the survivor likely transmitted EVD to his partner through unprotected vaginal intercourse approximately 179 days after EVD onset. Genomic data of semen and vaginal-secretion samples obtained from the EVD survivor and his partner were similar, but distinct from sequences from patients in neighboring countries. The survivor’s partner had no other known contact with EVD, according to the researchers, and a nearly completed genome assembly suggested infectious particles were present in the survivor’s semen specimen.

To investigate the persistence and viability of Ebola virus in semen, Gibrilla F. Deen, MD, from the Sierra Leone Ministry of Health and Sanitation, and colleagues assessed samples of seminal fluid from 93 EVD survivors aged older than 18 years from Freetown, Sierra Leone. Samples were collected during clinic visits and sent to the CDC field laboratory for PCR testing. Those with detectable VP40 and NP gene targets after 40 cycles of replication were identified as positive specimens.

Forty-nine percent of the cohort had detectable levels of Ebola virus RNA in their semen, according to the researchers. All patients tested 3 months after the onset of illness had positive samples (n = 9). Ebola virus RNA also was detected in 65% of men who reported symptoms 4 to 6 months before providing samples and 26% of men who reported symptoms 7 to 9 months before providing samples. The longest time between the onset of illness to positive identification was 284 days. The longest time between discharge from an Ebola treatment center and positive identification was 272 days.

The median cycle-threshold values increased with time, according to the researchers. The abundance of VP40 increased from 31.1 at 2 to 3 months to 35.6 at 7 to 9 months. Likewise, the NP gene target increased from 32 to 37.

“As part of the study, we will continue to test and collect semen specimens from these individuals until they have two consecutive PCR specimens that are negative,” investigator Barbara Knust, DVM, MPH, from the CDC, told Infectious Disease News.

Barbara Knust, DVM, MPH

Barbara Knust

In addition to PCR testing, the researchers will conduct virus isolation to determine whether the virus can be grown, she said.

“That is our best indicator of whether the virus is actually alive within that semen specimen,” Knust said. “PCR detects the virus RNA fragments, but it doesn’t tell you if the RNA is from a live virus or a dead virus that is still persisting in the body.”

In a related editorial, Armand Sprecher, MD, MPH, from Doctors without Borders in Brussels, said Ebola virus in RNA does not imply the substance is infectious. He wrote there are more than 8,000 male survivors, and most are nearly 1 year into their recovery.

“If sexual transmission from survivors were an important means of disease propagation, we would have seen a number of cases by now,” Sprecher wrote.

He also expressed concern over labeling male survivors in western Africa as an ongoing “threat” and wrote that men with new cases of EVD may be driven into hiding.

“Failing to exert extreme caution in the way we communicate the risk that survivors of EVD pose to the public might have devastating effects both on the well-being of the survivors and on the effectiveness of the surveillance we need to finally end this outbreak,” he wrote.

Until more information is known, however, the CDC recommends that men who were diagnosed with Ebola undergo regular testing and abstain from sexual activity or use a condom until their semen has twice tested negative for EVD, according to the press release. – by Stephanie Viguers


Deen GF, et al. N Engl J Med.2015;doi:10.1056/NEJMoa1511410.

Mate SE, et al. N Engl J Med.2015;doi:10.1056/NEJMoa1509773.

Sprecher A. N Engl J Med.2015;doi:10.1056/NEJMe1512928.

Disclosure: The researchers report no relevant financial disclosures.