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expert reaction to a study on the persistence of Ebola virus RNA in the semen of survivors, and accompanying report on sexual transmission of the Ebola virus

Researchers have published in the New England Journal of Medicine their work which reports that infective Ebola virus can be found in the semen of those who survived the disease up to nine months following initial infection.

 

Dr Nathalie MacDermott, Clinical Research Fellow, Imperial College London, said:

“We have known from previous epidemics of the persistence of live virus in the semen of male survivors up to 82 days from onset of symptoms. On this basis all male survivors were advised to abstain from sexual relationships or wear condoms for 3 months following their discharge from a treatment facility during this epidemic.

“As the epidemic progressed and the number of survivors steadily increased it became apparent that viral persistence was more prevalent than once thought and that the virus might persist longer than 3 months in certain bodily fluids. The bodily fluids where virus has been detected in survivors are semen,  breast milk, vaginal secretions, inta-ocular and cerebrospinal fluid. The length of time after survival that the virus is present in these fluids is still being determined although the NEJM paper provides some further insight into this in the context of semen. The test used to detect virus looks at the virus’ genetic material – this can be present even if the virus is not actually replicating or alive. The presence of the virus in these fluids does not necessarily mean it is transmissible to those coming into contact with such fluids. However there is evidence that sexual transmission can occur as demonstrated in the NEJM paper regarding a case in Liberia.

“The first study is limited by sample size but does demonstrate concerning findings – that viral genetic material is present in semen for up to 9 months following onset of symptoms of Ebola virus infection. Of note the authors have yet to determine if live, and therefore infectious, virus is present in these samples. However given reports of potential cases of sexual transmission and one confirmed case from Liberia documented in NEJM, even if sexual transmission is a rare occurrence,  the potential risks mean we must alter advice given to Ebola survivors. Where possible and appropriate, screening of bodily fluids of survivors should occur until those fluids are determined to consistently test negative for the virus. Advice should be given to abstain from sexual intercourse or practice safe sexual relations using condoms until the time the seminal fluid tests negative for the virus or if testing is not possible, a minimum of 9 months has elapsed since symptom onset of Ebola virus disease. It cannot be over emphasised that this must be done in a culturally sensitive manner and in a way which prevents further stigmatisation of Ebola survivors. These survivors already face a myriad of problems upon returning to their communities, information of viral persistence must be dealt with sensitively and appropriately at the community level to try and prevent additional stigmatisation.”

 

Dr Jeremy Farrar, Director of the Wellcome Trust, said:

“This new research shows that Ebola virus can persist in the semen and be transmitted sexually many months after the original infection has disappeared. The fact that there has so far been only one isolated report of this type of infection suggests that this kind of transmission may be rare, but it highlights just how much we still don’t understand about the Ebola virus, infection and recovery.

“It also reminds us that the Ebola epidemic could be far from over. With more than 17,000 Ebola survivors, it’s possible that further cases of delayed transmission and late complications will occur. We must remain vigilant and continue to monitor the long-term health of survivors so that any new infections can be identified quickly and measures put in place to prevent further cases.”

 

Prof. Jonathan Ball, Professor of Molecular Virology, University of Nottingham, said:

“This confirms that ebolavirus can persist in the genital tract for a considerable length of time – months after the virus has disappeared from the blood – and worryingly shows that this long-lived reservoir is a potential source of new infections.

“Whilst the risk of someone who has recovered from initial symptoms sexually transmitting the virus appears tiny, this research clearly shows that the risk is real and, given the unprecedented number of survivors who are potentially shedding virus, there is the real possibility of seeing sporadic outbreaks because of sexual transmission from these long-lived reservoirs.

“Clearly survivors and their contacts need to be aware of this risk and take appropriate precautions to prevent exposure to virus. It also raises the important question as to whether or not the potential numbers at risk form this possible route of transmission warrant trials on experimental vaccines to see if they can protect sexual partners of survivors, especially in cases where there is a reluctance to use condoms.”

 

Dr Derek Gatherer, Lecturer, Lancaster University, said:

“Although the presence of ebolavirus in the semen of male survivors has been noted since the first outbreak in 1976, the true extent of this phenomenon is only just emerging. Hard evidence for sexual transmission, backed up by molecular sequencing data, remains confined to the case reported today, but nevertheless there are strong grounds for believing that sexual transmission from survivors may be an important factor. The first of these is the epidemiological observation that Ebola virus disease outbreaks are often followed by smaller outbreaks in the same area within the space of 18 months, which would be consistent with rare sexual transmission events from survivors of the original outbreak. The second is that, although the degree of infectiousness of viral particles in the various places they may occasionally be detected in survivors (in addition to semen, eye fluid, breast milk and some nervous tissues) remains to be established, even poorly infectious virus in semen would present a threat owing to the likelihood that potential transmission events may occur regularly within a domestic setting between partners not using barrier contraception. Ebolavirus, even of low infectivity, in semen is therefore a greater danger than similar ebolavirus in other bodily fluids.”

 

Ebola RNA persistence in semen of Ebola virus disease survivors- preliminary report’ by Deen et al. published in New England Journal of Medicine on Wednesday 14th October. 

 

‘Molecular evidence of sexual transmission of Ebola virus’ by Mate et al. published in New England Journal of Medicine on Wednesday 14th October. 

 

All our previous output on this subject can be seen at this weblink: http://www.sciencemediacentre.org/tag/ebola/

 

Declared interests

Dr Nathalie MacDermott: I am writing the paediatric Ebola survivor guidelines for the WHO and am doing a PhD at Imperial College London, looking at aspects of Ebola virus disease which is funded by the Wellcome Trust ISSF scheme and the Institute of Global Health Innovation.

Dr Jeremy Farrar: The Wellcome Trust has joint funded several pieces of research and trials into diagnostics, treatments and vaccines for Ebola.

Prof. Jonathan Ball: No conflicts of interest although I am doing Ebola research

Dr Derek Gatherer: I hold an Early Career Small Grant (ECSG) from Lancaster University to study Ebola and have been participating in the National Institute for Biological Standards and Controls (NIBSC) project on Ebola diagnostics.

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