Monday, October 19, 2015

ECDC On Ebola Persistence & Rapid Risk Assessment







With the dramatic decline in Ebola cases in Western Africa, the risks of seeing imported cases in Europe (or elsewhere in the world) has gone down considerably.   It isn’t zero, but it is getting close.  

Two recent cases, however, have highlighted the unpredictability of the Ebolavirus.

First, the unexpected relapse of Scottish nurse Pauline Cafferkey, nine months after her recovery from the the virus.  Ms. Cafferkey remains in critical condition, and few details have emerged as to the progression of her illness, other than the detection of the virus in her cerebrospinal fluid (CSF). 

While considered a rare complication - given the lack of long-term follow up of many Ebola survivors - it isn’t entirely clear how rare.

Last week, in WHO: Study Shows Ebola Virus Fragments May Be Detectable In Semen For > 9 Months, we saw additional evidence of the long-term presence of the Ebolavirus in male semen, and last May (see MMWR & WHO On Risks Of Sexual Transmission Of Ebola) we saw evidence of the sexual transmission of the virus.


All of which may make getting to zero cases – and staying at zero – likely more difficult than previously believed.  


While none of this greatly increases the risks to the EU, the ECDC has updated their Rapid Risk Assessment and has posted a comment on these latest developments.


New Ebola rapid risk assessment update and virus persistence comment

19 Oct 2015

Updated rapid risk assessment

ECDC’s new rapid risk assessment on the West Africa Ebola virus disease outbreak re-assesses the risk of importation of Ebola virus to the EU and the risk of onward transmission following the decline of the outbreak observed in Guinea and Sierra Leone. It also considers the risks associated with a patient in the UK showing an unusual late complication of Ebola infection.

On 9 October 2015, the UK notified an unusual late complication in an Ebola survivor. The case is a nurse who was diagnosed with EVD on 29 December 2014, after returning from Sierra Leone to Glasgow. She was declared free of Ebola on 24 January 2015. The risk of further transmission from this nurse is considered very low, given the preventive measures taken and the continued monitoring of close contacts.

Further investigations are needed to fully understand the mechanism and impact of the re-appearance of viral RNA in this patient more than eight months after recovery. Ongoing cohort studies will hopefully provide more information about EVD survivors’ complications and long-term prognosis

The risk of EVD being imported into the EU has decreased to an extremely low level. The risk of further transmission in the EU from an imported case remains very low.

The re-emergence of EVD transmission in West-Africa remains possible as a result of transmission from a recovered case through contact with infected bodily fluids (e.g. through sexual contact), unrecognised or asymptomatic cases, or from reintroduction from the animal reservoir.

Recent studies on sexual transmission of the Ebola virus

Two studies published on 14 October in the New England Journal of Medicine provide insights into sexual transmission of Ebola virus and the duration of virus persistence in semen. The first study by Mate et al supports evidence of sexual transmission from a convalescent male survivor to his partner 179 days after the onset of disease, and 155 days after the clearance of Ebola virus from his blood. The second study by Deen et al summarises the results of a longitudinal monitoring of Ebola virus genetic material (RNA) in semen among survivors, demonstrating the presence of viral RNA in semen up to nine month after disease recovery.

Both studies are providing important findings on the sexual transmission of EVD and the potential persistence of the virus into semen. They need to be taken into account during the follow-up of the EVD survivors.

ECDC’s comment on the two studies: Recent development on sexual transmission of Ebola virus
Rapid Risk Assessment: Outbreak of Ebola virus disease in West Africa, 13th update

(Note:  Link to ECDC comment not currently working)