The persistence of the Ebola virus, detected in some organs and bodily fluids (i.e. semen, breast milk, etc.), among some survivors more than a year after their recovery (see ECDC On Ebola Persistence & Rapid Risk Assessment) has been an ongoing and evolving story.
In May of 2016, in Virus Evolution: Rapid Sequencing Reveals Rare Ebola Transmission Via Breast milk And Semen, we looked at a study that used genetic sequencing to identify the lineage of Ebola infections during the tail end of the outbreak in Sierra Leone, and which indicated sexual or breast milk transmission was likely in a handful of cases.The persistence of symptoms (see EID Journal Post-Ebola Syndrome, Sierra Leone), and Scottish Nurse Pauline Cafferkey's high profile relapse 9 months after her initial recovery, led the WHO to issue guidance, and the following assessment:
Today, there are over 10 000 survivors of Ebola virus disease. A number of medical problems have been reported in survivors, including mental health issues. Ebola virus may persist in some body fluids, including semen. Ebola survivors need comprehensive support for the medical and psychosocial challenges they face and also to minimize the risk of continued Ebola virus transmission.Despite these reports, cases of post-recovery transmission of Ebola have been hard to document. Yesterday the CDC's EID Journal published a synopsis of 13 suspected cases of viral persistence–derived Ebola transmission.
Due to its length I've only posted an excerpt. Follow the link to read it in its entirety.
Volume 25, Number 2—February 2019
Ebola virus (EBOV) can persist in immunologically protected body sites in survivors of Ebola virus disease, creating the potential to initiate new chains of transmission. From the outbreak in West Africa during 2014–2016, we identified 13 possible events of viral persistence–derived transmission of EBOV (VPDTe) and applied predefined criteria to classify transmission events based on the strength of evidence for VPDTe and source and route of transmission.
For 8 events, a recipient case was identified; possible source cases were identified for 5 of these 8. For 5 events, a recipient case or chain of transmission could not be confidently determined. Five events met our criteria for sexual transmission (male-to-female). One VPDTe event led to at least 4 generations of cases; transmission was limited after the other events. VPDTe has increased the importance of Ebola survivor services and sustained surveillance and response capacity in regions with previously widespread transmission.
The 2014–2016 outbreak of Ebola virus disease (EVD) in West Africa was the largest since the discovery of the Ebola virus (EBOV) in 1976 (1). More than 28,000 cases and 11,000 deaths were reported from the 3 most affected countries (Guinea, Liberia, and Sierra Leone) (2). An unprecedented number of persons survived; >4,500 of the estimated total of >10,000 survivors have been registered in the 3 countries (3).
EVD survivors often have substantial long-term medical sequelae (4), and viable EBOV can persist in immunologically protected body sites, such as the male gonads and the chambers of the eye (5,6). Viral persistence in body fluids, such as semen, creates the potential for transmission and initiation of new chains of transmission weeks or months after continuous community transmission has ended (7). On January 14, 2016, the World Health Organization (WHO) declared that human-to-human transmission had been stopped in West Africa.
However, WHO and its partners indicated that the 3 affected countries remained at high risk for additional EVD outbreaks because of virus persistence in survivors and emphasized the need for strong surveillance and response systems (8). A new EVD case was confirmed in Sierra Leone the following day (9), and another outbreak comprising cases in both Guinea and Liberia was recognized in March 2016 (2,10).
Infectious virus has been isolated from semen of Ebola survivors 82 days after symptom onset (11), and EBOV RNA has been detected by reverse transcription PCR (RT-PCR) in semen 531 days after symptom onset (10). Other body fluids, such as vaginal fluids, breast milk, urine, feces, sweat, and saliva, also have been shown to be RT-PCR–positive for short periods after recovery of the patient (11). Some evidence indicates that transmission could occur through breast milk (12), but confirmed transmission from viral persistence in the other body fluids has not been described (13). Before the West Africa EVD outbreak, 1 case of Marburg disease (14) and 1 possible case of EVD (15) attributed to sexual transmission had been reported. From the EVD outbreak in West Africa, several incidents of possible sexual transmission of EBOV from EVD survivors have been described in detail (10,16–19), as have viral persistence–derived transmission of EBOV (VPDTe) events for which the mode of transmission was unknown (12,20,21,22).
We describe a series of EBOV transmission events with evidence of transmission related to viral persistence in EVD survivors. Our findings are relevant for response planning, especially related to surveillance and response capacity, and for the development of policies and guidelines regarding survivor counselling, care, and management.(SNIP)
Our report has several key implications. EVD cases and clusters might occur after initial control of an EVD outbreak. Although previously available science supported the possibility of viral persistence, the West Africa outbreak clearly illustrated the potential consequences of EBOV persistence in terms of program needs, stigmatization of survivors, and risk that transmission from a survivor with persistent virus will trigger a new cluster. With this new reality, it is critical that the responses to EVD clusters include sustained vigilance, maintenance of response capacity, and continued efforts to reduce the risks that survivors in whom EBOV persists will transmit infection.
Dr. Den Boon is an epidemiologist and health economist currently working as a freelance consultant. Her primary research interests include priority setting of health interventions and implementation research to improve access to medicines.
While events like these appear to be exceedingly rare, with the DRC's current outbreak now the second largest Ebola epidemic on record, the potential for seeing a belated transmission from a recovered patient needs to be considered.
For more on the persistence of Ebola, you may wish to revisit:
Lancet Global Health: Traces Of Ebola Can Remain In Semen For Longer Than 1 Year
WHO: Study Shows Ebola Virus Fragments May Be Detectable In Semen For > 9 Months