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Scientist comment on an update from the UK Health Security Agency (UKHSA) on an evacuation of a UK humanitarian worker from the DRC.
Prof Jonathan Heeney, Professor of Comparative Pathology of Viral Infections and Head of the Lab of Viral Zoonotics, University of Cambridge, said:
“The UKHSA have taken precautionary measures and the suspected contact individual will be closely monitored in a safe and secure quarantine unit in case symptoms do develop (anywhere between 2 to 21 days). PCR diagnostic tests will probably be taken during this period, but usually only become PCR positive for the virus (about 3 days) after symptoms develop.
“There are investigational post-exposure prophylaxis (PEP) therapies that may be considered by the medical staff especially if this was a “high-risk” exposure.
“Amongst people identified as contacts with an Ebola patient, only a minority become infected (10 to 20% roughly), but this is dependant on the type of risk – i.e. close care givers have a much higher risk than casual contacts.
“The key issue is that Ebola is not highly contagious through casual proximity as it usually requires direct contact with body fluids from someone actively ill with Ebola disease.”
Dr Charlotte Hammer, Assistant Professor and infectious disease epidemiologist, University of Cambridge, said:
“It is a sad reality of Ebola outbreaks that there is a risk to those taking care of patients, both healthcare workers and family members, to be exposed and infected in the course of doing so. In this current outbreak, as far as we know, at least 119 healthcare workers have been infected (data as of the 15th of July) and 36 have died. This particular outbreak is unfolding in a very complex environment and we have seen attacks against treatment centres, which makes the work of the healthcare workers more complicated and dangerous.
“In the current case, we are seeing an application of precautionary measures for an individual who is not currently showing symptoms but has had a potential exposure. Importantly, this is not only for the benefit of public safety but also for the benefit of the individual so that they can be treated if they should develop symptoms over the span of the up-to-21-day incubation period.
“The wider situation in the DRC remains very challenging. The outbreak is continuing across a large geographic area and response efforts are taking place in a complex humanitarian setting characterised by population displacement, insecurity and limited access to healthcare in some affected communities. As of 15 July, more than 2,100 confirmed cases and more than 800 deaths had been reported in the DRC.”
Prof Paul Hunter, Professor in Medicine, UEA, said:
What could a potential healthcare related exposure be?
“Ebola is not that transmissible, and you usually have to have close contact with a case, particularly a case with severe or end stage disease, or their body fluids. This is one of the reasons why health care workers are at a particularly high risk as they care for dying patients. Actual events that could be classed as an exposure could include a needlestick injury, skin to skin contact, having blood splash on your skin, or into your mouth or eyes. One of the few cases of Ebola acquired outside of Africa was in a Spanish nurse and the view was that this happened whilst she was removing blood stained PPE.
“This is what we published about transmission risks at some ten years ago: Brainard J, Hooper L, Pond K, Edmunds K, Hunter PR. Risk Factors for Transmission of Ebola or Marburg Virus Disease: A Systematic Review and Meta-analysis. International Journal of Epidemiology 2016; 45: 102–116 https://doi.org/10.1093/ije/dyv307
What do we know from evidence about the level of risk that medics and humanitarian workers face in the DRC?
“As of last week there were 2145 confirmed infections and 830 deaths, though these figures probably substantially underestimate the actual numbers https://www.who.int/emergencies/disease-outbreak-news/item/2026-DON613. Of these cases 119 cases and 36 deaths have been in health care workers. Of the three confirmed cases previously repatriated to Europe (one France and two US citizens in Germany) two were health care workers and the other a humanitarian worker with no patient contact as far as I can tell. I do not know how many cases in local humanitarian workers may have occurred. However the risk in workers with no patient contact will be substantially lower than in health care workers with patient contact.
How and when would we know if this individual has contracted Ebola – what tests will be being carried out?
“Diagnosis is by blood test usually a PCR test and we would expect results to be available usually within a day of the sample reaching a competent testing laboratory. However, the tests only become positive around the time that symptoms develop and that can take up to three weeks.
What is the risk to the general public in the UK?
“The risk to the general public remains very low. The suspect case will be being cared for in a specialist unit with highly trained doctors and nurses who will themselves be being monitored.”
Declared interests
Prof Jonathan Heeney: “I have no conflicts of interest. I am the author of the 2015 paper in Nature paper Ebola’s “Hidden reservoirs”. This paper hypothesized that filoviruses could hide undetected by the immune system in “privileged” areas like the testes or eyes. When genomic sequencing was completed on the 2021 Guinea cluster, it confirmed this hypothesis and caused global agencies to rewrite their protocols for long term followup.
Dr Charlotte Hammer: “I do not have any interests to declare.”
Prof Paul Hunter: “My CoI is I am in receipt of three grants from NIHR, one is on Outbreak Related Behaviours led by colleagues in King’s and another is in approaches for helping health facilities in low-income countries cope with extreme weather events. In the later grant one of our study areas in in North West Uganda close to the border with DRC where the main focus of the epidemic is. Some years ago we also published a series of studies around transmission risks of Ebola and I was on a joint international agency (WHO, UNICEF, MSF, etc.) advising on infection prevention during the West African epidemic in 2015.”