Introduction to the Ebola evidence collection

The outbreak of the Ebola-virus epidemic is a human catastrophe, taking place in some of the world’s poorest countries. Evidence Aid is working with partners to compile evidence-based resources that might help with the response and improve communication and information provision. You can read more about the need to avoid inaccurate and contradictory information here. Our resources will be updated as the situation changes and have been divided into a number of main categories.

Introduction

The Ebola Outbreak in West Africa 2013-2016 was a unique and extraordinary event in the modern history of public health and international affair. A total of 28,610 people were known to have been infected with Ebola, of whom 11,308 died, although in reality the actual numbers are likely to be significantly higher, since many cases went unreported. Communities, particularly in Sierra Leone, Liberia and Guinea, were devastated by the disease, as well as from secondary impacts on health care, education, and the economy. The disease also spread into five other countries – the USA, the UK, Spain, Mali and Nigeria – with cases treated in many others.

Ebola Virus Disease is a viral haemorrhagic fever that was first identified in 1976 in the Democratic Republic of the Congo. By 2014, a total of twenty-four outbreaks had been recorded, but these had been confined to a limited geographic region in East and Central Africa. The deadliest of these had been the 1976 one, in which 280 people died – 88% of those infected – although six of the other outbreaks had killed fewer than ten people or none at all.[i]  Outbreaks of EVD continue to sporadically occur, including a significant outbreak in the northern part of the DRC in 2018 that led to at least 66 cases and saw transmission within the city of Mbandaka, with a population of over 1 million inhabitants, showing that EVD continues to post a major public health threat.

Prior to the West Africa outbreak, little was known about EVD and the best approaches to its treatment or control. A critical lesson was that the range of issues and academic disciplines that underpin the causes of these outbreaks and the enablers of an effective response is much broader than just biomedical science. A technical understanding of virus transmission and effective laboratory diagnosis and clinical care are essential, but so too are an understanding of field epidemiology, anthropology, public communication and health policy. These proved essential for winning public trust in the response and developing strategies to maintain essential public services in a health crisis.

From the biomedical perspective, there was a significant research response on trials of novel therapeutic agents. Many of these were implemented at a late period in the outbreak, when cases numbers were dwindling and the likelihood of recruiting enough patients to reach a primary endpoint diminished. As such there remains uncertainty about the likely effectiveness of many novel drugs and compounds trialed – the monoclonal antibody complex ZMappTM and the antiviral agent Favipriravir show some promise, and the small interfering RNA molecule TKM-Ebola was shown to be ineffective.  Innovative methods of vaccine delivery were a clear success, with a ring-fence vaccination trial of a recombinant vesicular stomatitis virus–Zaire Ebola virus vaccine proving highly successful at preventing EVD in both close contacts of EVD cases, and their wider communities. This involved a multinational collaboration between academia, non-governmental organizations, and national and international agencies, and involved distributing the vaccine among new communities affected by disease rather than pre-determining where it would be delivered.

There was significant progress on laboratory diagnostics, both in the widespread use of molecular techniques such as real-time polymerase chain reaction (RT-PCR), and the more limited trials of near patient rapid diagnostic tests (RDTs). More field validation of the later is required, along with the overcoming the commercial challenges of making them available to those in need in future outbreaks. There has also been greater clarity on clinical presentation, and the factors that affect mortality.

Reductions in healthcare utilisation, alongside the increased mortality from other infectious diseases, maternal complications, and lack of general medical and surgical care have been detailed.  Community engagement, the use of traditional communications and social media in spreading preventative messaging, and novel methods of disease surveillance have been well documented.

However, despite the unprecedented numbers of patients treated in West Africa in 2013-2016, many important research questions remain, from the most basic clinical questions such as routine use of broad spectrum antimicrobial agents and anti-malarials, whether to use anti-diarrhoeal agents to stop electrolyte losses, or which corrective intravenous fluids bets replace bodily losses, to the more complex challenges of the best delivery of a multi-faceted public health response.

Future responses to EVD and other diseases must learn from the lessons and evidence that have been collected, which is set out in this collection, as well as identifying the unmet challenges that need to be urgently addressed. Only through evidence to action can future EVD, and other emerging infection outbreaks, be best combated.

Authors: Dr Oliver Johnson, Visiting Lecturer, King’s Centre for Global Health & Health Partnerships, School of Population Health & Environmental Sciences, King’s College London; Dr Colin Brown, Department of Infection, Royal Free London NHS Foundation Trust, London, UK *and* National Infection Service, PHE Colindale, Public Health England, London, UK.

[i] Centers for Disease Control (n.d.) Outbreaks Chronology: Ebola Virus Disease [online]. Available from: https://www.cdc.gov/vhf/ebola/outbreaks/history/chronology.html (Accessed 24 August 2017).

Systematic reviews and resources

If you would like to use an appraisal framework when considering the relevance and quality of the full reviews that Evidence Aid links to, a few useful tools are: AMSTAR, CASP and ROBIS. Guidance is also available on reporting reviews: PRISMA.