Ebola Virus – Expert Q&A

Rowena Clark / Adventure Medic Editor

The current Ebola outbreak in West Africa has given rise to immeasurable horror both locally and, increasingly, internationally. In some upcoming features, we will try to cover points of view from various different experts: from those ‘behind the scenes’ arranging the response to volunteers in the field.

Coverage of the outbreak in the press has been extensive, but has frequently not said that much about the virus itself. So, with huge thanks to Professor Ian Jones (Professor of Virology at the University of Reading), Professor John Edmunds (Professor in Infectious Disease Modelling from the London School of Hygiene & Tropical Medicine (LSHTM)) and Dr Adam Kucharski (Research Fellow in Mathematical Epidemiology from the LSHTM) for their expert input, here is our Adventure Medic Ebola Q&A.

What is Ebola and what are its predominant symptoms?

Ebola disease is is the consequence of infection by Ebola virus, a zoonotic virus discovered in 1976 that circulates naturally in fruit bats in equatorial Africa. Infection of man is accidental and is likely to occur via consumption of bat meat or via their droppings. It is a viral haemorrhagic fever, with the leading symptoms being fever, vomiting and diarrhoea; as disease progresses, internal and external bleeding occur.

What is its pathophysiology, and does this strain differ from others that have been isolated?

There are five known strains of Ebola; this is the Zaire strain, the same as the one first isolated in 1976. The virus encodes proteins which antagonise the innate immune response allowing it to replicate and spread body-wide. When the immune system eventually wakes up to the infection it overreacts and releases a flood of cytokines. Some of these are responsible for the vasodilation that worsens the haemorrhage. Other species can also be infected and the decline of gorilla numbers in equatorial Africa is also in part due to Ebola infections.

How does Ebola differ from other viral haemorrhagic fevers, and what is the natural geographical distribution for outbreaks?

Innate immune system dysfunction and unregulated cytokine signalling underlie most viral haemorrhagic fevers, but Ebola is one of the most pathogenic. It was previously only found in rural populations in equatorial Africa, and the rise of this epidemic was partly the result of location: the first countries affected were amongst the world’s poorest, areas where long periods of civil war have battered health services and eroded public trust. Survival is directly linked to early diagnosis and treatment. Interestingly, children seem to be less affected, possibly because they are less likely to care for affected patients.

How is it diagnosed and treated?

Clinically, Ebola infection is initially characterised by sudden onset fever with a history consistent with exposure. Confirmation is via detection of viral nucleic acid by the polymerase chain reaction (RT-PCR). Treatment is essentially supportive, which ultimately comes down to fluid and plasma replacement and organ support as able. Newer treatments are being trialled (and have been tried) mostly in Western volunteers who have been infected. These uniformly aim to “slow the virus down” either by providing an immune blockade (e.g. ZMapp) or by inhibiting virus replication (e.g. Favipiravir). However the evidence base for the effectiveness of any of these is almost non-existent as very few people have had these treatments and a full assessment has yet to be made.

Why is this outbreak so bad and how does it spread?

Every Ebola outbreak to date has previously been stopped by relative prompt action and contained by contagion control, barrier nursing, contact tracing/monitoring and isolation as required. Sequence data shows that the current virus has not substantially changed – this is not a new variant with unusual transmission properties. Accordingly, this outbreak could be controlled in the same way as all previous outbreaks. The spread in West Africa is the result of social and economic factors which include a lack of trust in ‘Western-style’ medical intervention. Funerary rites are a major source of onward transmission, and there is also some denial and much understandable fear. Coupled with an inadequate infrastructure, at-risk individuals either shun the support offered or move elsewhere, spreading the infection.

Ebola spreads through direct contact with the blood, organs or other body fluids of infected people, via broken skin or mucous membranes. It is worth remembering that contact with anything contaminated (e.g. sheets, clothes) can also transmit the disease. The virus can remain in the blood and other fluids (e.g. semen, breast milk) of those who have been infected for up to seven weeks after recovery.

There is little doubt that getting a convincing public health message to the rural at-risk communities is as important as direct clinical intervention. Governments, WHO and NGOs have woken up (while some, like MSF, have been on the ball from the start). But the epidemic has been doubling every few weeks. So unless you can outstrip this (in terms of isolation beds etc) you will fall further behind, and so it gets worse. The end is not in sight, but there may be a glimmer of hope: cases seem to have dropped recently in Liberia (the worst affected country).

What is the potential for viral mutation, and what might be the impact/relevance of any mutation?

Ebola is an RNA virus and exists as a mix of genotypes: a quasispecies. Mutation is therefore part of Ebola replication. As noted, however, there is no evidence of a dominant change in the current outbreak so it is not much of an issue – no selection pressure appears to be driving Ebola evolution. In fact the virus shows no fixed change when compared to the original 1976 strain so a change of lifestyle, for example to aerosol or insect transmission, is very unlikely. However, there is a possibility that the virus could evolve to become less pathogenic, which would enable hosts to travel – and transmit – for longer.

There is much in the media at present about novel treatments, vaccines and anti-virals – are any of these likely to be introduced soon, and are they effective?

They have all been shown to be effective in animal models so they will probably be effective in man. But there are substantial logistical issues even if they become more widely available. Antivirals require rapid diagnosis and knowledge of half-life and toxicity if given prophylactically. Vaccines may offer protection to heath care workers but their more widespread use requires access to those at risk, currently one of the major reasons the outbreak continues to spread. They don’t really stop transmission (as those getting them will already be in isolation). And there is no data yet on whether protection is possible with a single immunisation or if multiple boosters are needed, again an issue for rural community vaccination. In addition, we will absolutely need a vaccine for the next time that this happens.

What is the risk to healthcare professionals working with those affected?

The risk has been huge, predominantly to local staff. For every ten cases in the community, one member of front line staff (not just healthcare workers) gets infected – however, that was using data to the middle of August that may now be out of date. It looks as though recently, as improvements have been made to protection and awareness, that the risk to staff has fallen quite significantly. Full Personal Protective Equipment (PPE) is required for contact with an Ebola patient as infection occurs by direct contact with body fluids. The incubation time for Ebola can be up to 21 days so that is the current WHO advised quarantine period.

How would a country such as the UK cope with an outbreak of Ebola? Would survival rates differ greatly from those seen in W Africa?

The risk of a large outbreak in Europe or the US remains extremely low. Any incoming case would be picked up quickly through current alert systems. A number of specialist isolation facilities are available, for example at the Royal Free Hospital in London, and any cases would be quarantined and treated at such a facility. Contact tracing and follow up would minimise spread, and in fact both Nigeria and Senegal have recently controlled imported infections using such measures. Because of this, survival rates in a country such as the UK would be much higher than those typically quoted – possibly about 30%, based on those evacuated to countries with a better medical infrastructure.

Should volunteers and health professionals from the other countries become involved?

It is clear that tackling Ebola will require a huge international response. People on the ground providing direct clinical care, those in epidemiological & public health roles, and people giving logistical & bureaucratic support are key to curtailing this outbreak; it is evident that the local infrastructure is inadequate in this regard. Facilities are being built at a great rate in Sierra Leone right now, but they will be worthless without staff going out there. Hundreds of staff have already volunteered to work with health agencies in affected countries, and it is crucial that they have sufficient resources to fight the infection. This includes protective clothing & isolation units, and diagnostic tools and laboratory testing facilities. Authorities must also engage with communities to build trust and encourage patients to reduce transmission and seek isolation. Volunteering plays an important role but should always be via an organisation that has long and direct experience in the field. If you do volunteer, be utterly professional. Whatever your sentiment, place your trust in the training and procedures established over time and follow them absolutely. And only become engaged through an established route. See below for more information on sensible places to start for anyone considering becoming involved.

What scares the experts most about this particular outbreak?

That ignorance, fear and geographic and political obstructions obscure the science. Contagious disease is understood and can be controlled but requires a willingness to engage with the required processes. Ebola is unlikely to be a pandemic but the current outbreak could smoulder for many more months yet if access to the most at risk populations does not improve. There is a risk that it could become established in the region, and clearly has the potential to become a disaster in more countries, particularly those with precarious access to rapidly available, adequate healthcare.

The WHO Director-General has declared this outbreak a ‘Public Health Emergency of International Concern’. What has the current international response to this outbreak been like following this, and can we (the public/healthcare professionals based in developed countries) do more to help?

One cannot over-react to this. The international response is getting ramped up, but is still too slow. The declaration of a PHEIC should improve the flow of resources to the region and so is to be welcomed,  but there has to be change on the ground for these measures to have an effect and at the moment that still appears limited. At home, support can occur in many forms from volunteering to fundraising. A panic-orientated media is not always helpful, so a measured scientific response to public concern is also valuable. The challenge of improving education and infrastructure in the communities affected is the longer-term goal that ultimately feeds through to better control of future outbreaks.

Interested in becoming involved?

If you are looking to volunteer, please ensure that you do so through formal, well-established means. Think it through and read up on what will be expected of you in order to avoid becoming a hindrance rather than a help.

Each country will have their own avenues for volunteer potential. Here are some useful links for those in the UK:

Photo: Ebola virus virion. Created by CDC microbiologist Cynthia Goldsmith, Public Health Image Library, #10816.

Watch this space for further articles on the UK response and from those who have been volunteering in the field.