Persistence Of Ebola Virus In Survivors & Risks Of Sexual Transmission: A Systematic Review

Allison Cheung

This thesis is restricted to Yale network users only. It will be made publicly available on 08/28/2021


Background: Longitudinal cohort studies of Ebola virus disease (EVD) survivors from the 2014-2016 West African outbreak have found evidence of Ebola virus (EBOV) and EBOV RNA persistence in the bodily fluids of survivors, particularly in semen. This new evidence has raised the possibility of sexual transmission of EBOV by EVD survivors. The current interim guidance issued by the World Health Organization (WHO) recommends safer sex practices for at least 12 months after acute disease onset (ADO). However, based on new evidence, these recommendations may require revision.

Objective: The main aim of this article is to present and evaluate evidence on the persistence of EBOV in genital fluids, as determined by RT-PCR or viral isolation. In addition to determining the length of persistence in these genital fluids, the relation of persistence to sexual transmission of EBOV is also examined.

Design: We conducted a systematic review of viral persistence in semen, vaginal, and rectal fluids, and assessed evidence of the potential transmissibility of persistent EBOV via sexual transmission from survivors.

Results: We identified 42 published original studies presenting results on EBOV persistence or reporting on suspected sexual transmission of EBOV from survivors. EBOV RNA has been detected in the seminal fluids of an EVD survivor for up to 40 months post-EVD onset. From a cohort of nearly 2,000 male survivors, we estimate an average length of EBOV RNA duration of 370 days. EBOV has also been detected by viral isolation for up to 82 days. Finally, we report that age is a potential determinant of EBOV persistence, with older age associated with a higher likelihood of EBOV RNA detection in seminal fluid.

Conclusion: On the basis of the evidence reviewed, we conclude that persistence of EBOV RNA is related to an increased risk of sexual transmission of EBOV, though the evidence remains mixed on whether detectable EBOV RNA necessarily signifies the presence of infectious virus. Due to reports of intermittent detection of EBOV RNA, especially among survivors who experience EBOV persistence for over a year, we recommend that at least two negative RT-PCR results be received before declaring the survivor’s seminal fluid to be cleared of EBOV RNA.