Sexual Transmission of Ebola

Apr 1, 2015 | Marie Killerby Colleen Nguyen | Outbreak News

Over the weekend, various news sources announced that the Liberian government recommended indefinite sexual abstinence or condom use for Ebola survivors in light of the 2014-2015 West Africa outbreak ravaging the region [1]. Recent media reports speculate that a recent Ebola case in Liberia, acquired the virus through sexual transmission – though this has not been confirmed [2]. Currently, the World Health Organization (WHO) recommends that whilst sexual transmission of Ebola virus has not yet been verified or documented, it may be possible and sexual transmission from convalescent patients cannot be ruled out [3].

Due to the potential risk of Ebola infection through sexual contact, the WHO currently recommends that condoms be worn for a minimum of three months by Ebola survivors [3]. This recommendation is based on a study in which semen samples from five men were tested for presence of Ebola virus [4]. In one semen sample, taken 82 days after recovery from illness, they discovered live Ebola virus. The virus from that sample was then grown in cells in the laboratory, suggesting the virus could still be transmissible. However, no live virus was found in the semen samples tested from the four other individuals, each sampled across one to three time points between 51 and 707 days after infection [4,5]. Other studies have shown evidence of live virus surviving for shorter times -- for example, only up to 40 days after recovery when testing one patient [6]. Studies have also found genetic fragments of virus in semen even longer after infection, e.g. up to 101 days after infection [4]. However, genetic fragments alone are not necessarily infectious, therefore given 82 days is the longest time after recovery when live virus has been found, this aided in the formation of the recommendation that condoms should be worn for a minimum of three months.

Overall, these studies have shown that it is possible to find live, infectious Ebola virus in the semen of men recovering from Ebola virus. However, given that only a small number of semen samples have ever been tested, the maximum amount of time over which live Ebola virus could be present in semen is currently unknown. Although there has been no confirmed case of sexual transmission of Ebola in past outbreaks, there has been a single described instance of sexual transmission of Marburg virus, a closely related virus from the same family, filoviridae [7]. Even less evidence is available for the possibility of sexual transmission from female Ebola survivors -- one study found detectable genetic fragments of Ebola up to 33 days after recovery, but no live virus [4].

Therefore, given the limited evidence on the amount of time for which live, transmissible Ebola virus could be present in semen, recommendations have had to be made on the small amount of evidence available. However with the current outbreak, as new evidence comes to light, recommendations may change with time as more is learnt about the virus. Therefore, the biological possibility of sexual transmission of Ebola should not generate further fear and stigma for survivors. Instead, it is important for the implications of sexual transmission to be carefully discussed, both in considering appropriate recommendations for sexual protection and ensuring that people remain vigilant to the possibility of further Ebola transmission happening later in time than expected. Further scientific research is also needed to quantify the risk of infection from Ebola survivor’s semen, as well as to determine how long this risk is present for.








4. Rodriguez, L. L., A. De Roo, Y. Guimard, S. G. Trappier, A. Sanchez, D. Bressler, A. J. Williams, et al. “Persistence and Genetic Stability of Ebola Virus during the Outbreak in Kikwit, Democratic Republic of the Congo, 1995.” The Journal of Infectious Diseases 179, no. s1 (February 1999): S170–76

5. Rowe, Alexander K., Jeanne Bertolli, Ali S. Khan, Rose Mukunu, J. J. Muyembe‐Tamfum, David Bressler, A. J. Williams, et al. “Clinical, Virologic, and Immunologic Follow‐Up of Convalescent Ebola Hemorrhagic Fever Patients and Their Household Contacts, Kikwit, Democratic Republic of the Congo.” The Journal of Infectious Diseases 179, no. s1 (February 1999): S28–35.

6. Bausch, Daniel G., Jonathan S. Towner, Scott F. Dowell, Felix Kaducu, Matthew Lukwiya, Anthony Sanchez, Stuart T. Nichol, Thomas G. Ksiazek, and Pierre E. Rollin. “Assessment of the Risk of Ebola Virus Transmission from Bodily Fluids and Fomites.” The Journal of Infectious Diseases 196, no. s2 (November 15, 2007): S142–47

7. Slenczka, Werner, and Hans Dieter Klenk. “Forty Years of Marburg Virus.” The Journal of Infectious Diseases 196, no. s2 (November 15, 2007): S131–35

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