Investigation: Oxford’s role in the fight against Ebola

The World Health Organisation (WHO) has estimated that since the outbreak of the latest Ebola epidemic in 2013, there have been 23,217 suspected cases and 9,353 deaths. Scientists from Oxford University have played an integral part in leading the effort to fight it. This has mainly consisted of setting up clinical trials to test the efficacy and safety of both possible vaccines and possible cures. The investigation this week takes a deeper look at this contribution, and interviews some of the researchers behind it. The articles featured below introduce the investigation. They give an explanation of the key things to know about Ebola, as well as a first hand account of the practical considerations researchers face when working in the field.

Other articles in this investigation:

Fever, headache, muscle pain, diarrhoea: an introduction to Ebola

Chanatjit Cheawsamoot

In October 2014, the World Health Organisation (WHO) concluded that the current Ebola epidemic is larger than all past Ebola outbreaks combined. While most people will have begun to be aware of the Ebola epidemic in the autumn of 2014, the start of the outbreak was actually much earlier – in late 2013. The epidemic began in Guinea during December 2013 and the WHO was officially notified of the rapidly evolving Ebola disease outbreak in March 2014. The three most affected countries in West Africa – Guinea, Liberia, and Sierra Leone – face an immense challenge as they try to control the spread of the Ebola virus and to provide treatment for all those infected. 

Although the current outbreak is exceptionally large, there have been previous outbreaks of Ebola before in West Africa, albeit on smaller geographic scales. The WHO speculates that the larger scale of this epidemic is due to certain characteristics of the affected populations and insufficient control efforts. For example, the populations of Guinea, Liberia, and Sierra Leone are highly interconnected, with relatively easy connections by road between rural towns and villages and between densely populated national capitals, providing a golden opportunity for the Ebola virus to spread among populations. Symptoms of Ebola include fever, severe headache, muscle pain, diarrhoea, and unexplained haemorrhage.

The natural reservoir host (the long term host of a pathogen for an infectious disease) of the Ebola virus remains unknown. However, current evidence suggests that reservoir hosts for the Ebola virus are likely to be bats, suggesting a possibility that humans became infected directly from bats in caves, as well as when they come into contact with tissue from infected apes and other species.

 

Transmission of the Ebola virus is through blood and body fluids – including but not limited to urine, saliva, sweat, faeces, vomit, breast milk,and semen of a person who is sick with Ebola. It is not spread by air, water, or food. As Ebola doesnot spread through casual contact, the risk of an outbreak outside of Africa is very low if effective hygiene control measures are implemented.

As for all diseases, epidemiologists strive to calculate the basic reproduction number (R0), which is the key to figuring out how infectious a disease is. It expresses how many people one infected person can pass the disease onto. This value for Ebola varies from population to population but they are all close to two, indicating that each infected person has the potential to pass on the disease to two other people. Compared to other epidemics in the past, the basic reproduction number of Ebola is much smaller. For example, measles had an R0 value of 18 before a vaccine was procured. This shows that even though the fatality rate is high (around 60 per cent), the Ebola virus is not very good at transmitting itself at all.

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Thus, one strategy in controlling the epidemic is reducing the basic reproductive value to below one, which means that an infected person will no longer pass the disease on to anybody, effectively preventing the spread of Ebola. This can be done via the isolation of infected patients to prevent the transmission of the virus to uninfected people.

With the prospects for a novel and successful Ebola vaccine, immunising just over half of the affected populations can halt the spread of the Ebola virus. Of course, ensuring that everyone who is at risk is immunised would be desirable but this level is the minimum that is needed to contain the Ebola virus disease.

Because the Ebola virus is spread mainly through contact with the bodily fluids of symptomatic patients, transmission can also be prevented by a combination of early diagnosis, contact tracing, patient isolation, and care and safe burial. Contact tracing involves finding everyone who has come into contact with an Ebola patient, after which they are tracked for 21 days for signs of illness. If a contact develops Ebola symptoms, they are immediately isolated and provided with treatment. This process is crucial in stopping the spread of the disease.

As vaccines against the Ebola virus are being tested for safety and effectiveness, other treatments are used to maintain the health of patients, such as providing intravenous fluids, maintaining blood pressure, and treating other infections if they occur. Until then, successful recovery from Ebola depends on the patient’s immune response and the quality of supportive care. As vaccine trials for Ebola are being carried out at The Jenner Institute in Oxford, there is yet hope that a cure will be found.

 

Pierro Olliaro, a professor of Tropical Medicine working on Ebola, discusses the practical elements of his work

Ebola is a deadly disease, but fortunately it cannot be transmitted as easily as can, for instance, flu: it needs direct contact with body fluids, and only a person with symptoms can pass the virus onto another person. The virus circulates in nature, and humans can occasionally catch it from infected wild animals, like bats and monkeys. Then, when the person starts developing symptoms – and only then – they will start infecting other people around them. Particularly dangerous are traditional burials, which can generate many more cases from one single instance.

In the past, epidemics have generally been confined to remote areas and were curbed before they reached highly-populated areas. Unfortunately, this is not what happened this time. In the countries in West Africa where Ebola has spread havoc during this last epidemic, people, governments, and international aid generally underestimated the magnitude of the problem, probably thinking that the epidemic would simply die down on its own. Ignoring the looming disaster, life carried on as usual, unsafe practices continued allowing the number of cases to pile up and the disease to spread further afield – to amount to an appalling 23,000 cases as of today.

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When I first visited West Africa in October 2014, several months into the epidemic, it had become only too obvious how real the problem was, and a number of measures had been set in place to hold off the spread of the disease.

Simple measures are very effective: do not touch anyone, touch as few things as possible, possibly avoid public transportation, and wash your hands as often as possible. Tanks of chlorinated water stand outside shops, offices, hotels with which you are required to wash your hands before entering; hand antiseptics are in high demand.

Things change completely when it comes to getting close to a suspected or confirmed case in a screening or treatment centre. Here, the risk of exposure increases with medical acts like visiting a patient or taking a blood sample.

Doctors and nurses wear personal protective equipment (PPE) clothing that covers them from head to toe. Donning the PPE, including mask, visor or goggles, hood, apron, etc. takes about ten minutes, and doffing it takes even longer – it is the most critical part of all, to prevent infected material possibly present on the outside from getting in touch with the body. In between, one would have spent one hour inside; at this point the scrub that you are wearing underneath would be completely soaked, wellies and surgical gloves (two pairs) filled with sweat that had trickled down. Scrupulous adherence to very strict procedures has proved very effective: of the hundreds of healthcare workers who have been treating thousands of Ebola patients in this epidemic, very few have become infected, mostly because of needle injuries or a breach in protocol.

If being in an Ebola-stricken country is a poignant experience, returning can be quite a journey. Your temperature is checked and you are questioned several times as to what you have been doing at the airports of embarkation, transit, and arrival.

On landing in the UK, Border Control will know where you have been, even if you’d stopped over for a few days elsewhere on your way back. You will be asked kindly to wait for a Public Health England (PHE) official to come and assess you. If you’ve been deployed to work on Ebola (one would hardly think of visiting those countries as a tourist, these days), PHE would be fully aware of your movements and whereabouts, and would provide you with instructions and have a box delivered at your home with various materials, including a tympanic thermometer.

This latter piece of equipment will become your closest pal for the next three weeks. You will have to measure your temperature twice a day and will have to report any fever or symptoms. A form of paranoia kicks in, as in winter, you could catch flu or any other seasonal bug from your kids at home or Joe Bloggs in the street.

But that’s not all. Dealing with people and perceptions back home will be a challenge. Despite scientific evidence that one can only transmit the infection if symptomatic, not all, including some close friends, would be prepared to entertain the same relationship with you as they would have done otherwise, “out of an abundance of caution”, they claim. Such should not be the case, at the level of individuals or a country. Let’s de-mystify beliefs.