Ebola virus can persist for at least nine months in the semen of male survivors of the disease, WHO research has confirmed. The research, published in NEJM, was prompted by the case of a Liberian woman who contracted Ebola after the country was cleared of the virus, as described in accompanying case report. The woman’s […]
Ebola virus can persist for at least nine months in the semen of male survivors of the disease, WHO research has confirmed.
The research, published in NEJM, was prompted by the case of a Liberian woman who contracted Ebola after the country was cleared of the virus, as described in accompanying case report. The woman’s only exposure had been sexual contact with a survivor of the disease 155 days after his recovery.
The researchers examined semen from 92 survivors of Ebola virus disease using real-time PCR. Viral RNA was found in 11 of 43 samples obtained 7 to 9 months after onset of symptoms. Sixty five per cent of samples four months post-onset were positive for the virus, as were all samples collected at two months post onset.
It is not known how long Ebola virus in semen will remain infectious as cases of suspected sexual transmission of Ebola are rare, an expert said.
“It remains an extremely low likelihood event but what is concerning is the duration of viral persistence,” said Dr Susan McLellan, Clinical Associate Professor of Tropical Medicine, Tulane University, New Orleans.
“The mere suspicion of sexual transmission had already changed recommendations from WHO that male survivors should not have unprotected intercourse until they have been shown to no longer have virus in their semen,” said Professor McLellan.
Concerns have also been raised about the ability of the virus to survive in different bodily environments. Commenting on the research, Dr Ilhem Messaoudi, Associate Professor of Biomedical Sciences at the University of California, said the virus appeared more versatile than originally thought.
“The article reports no changes between the genome sequence that they found in the semen of the survivor and the patient’s blood. So it seems that it did not need to mutate in order to survive.”
“We need more molecular studies in order to understand … what the difference is between individuals who have persistent virus and those who do not,” he said.
The NEJM publications coincide with the readmission to hospital of British nurse, Pauline Cafferkey, after she had recovered from Ebola nine months ago. While Ms Cafferkey’s illness is still being investigated, experts are shocked at its severity.
“I am not aware from the scientific literature of a case where Ebola has been associated with life-threatening complications after someone has initially recovered, and certainly not so many months after,” said Jonathan Ball, professor of molecular virology at the University of Nottingham.
Professor Susan McLellan said, “Cases like [the NEJM report] and that of the London nurse, Pauline Cafferkey, are bringing up some really concerning possibilities about persistence of this virus that in some situations could lead to recurrence of outbreaks.”
With 17,000 Ebola survivors from the latest and worst-recorded outbreak of Ebola virus in West Africa this is a significant fear. UK health officials are now monitoring 58 people who have had close contact with the affected nurse and imposed restrictions on their travel.
NEJM 2015; October 14
