Emergence of the Ebola Virus Disease in West Africa

Introduction

An emerging infectious agent is defined as a causative agent of a new or previously unrecognised infectious disease in a defined population. The Ebola virus has been implicated as a causative agent of viral haemorrhagic fever occurring in Central Africa over the last thirty-nine years (Baize et al., 2014). People living in West Africa have certainly been familiar with outbreaks of another zoonotic virus causing an acute viral illness: Lassa virus. However, the Ebola virus has not previously been recognised as an endemic virus causing outbreaks of viral illness in West Africa.

The start of what was to become the largest Ebola virus disease (EVD) outbreak in known history was first reported to the World Health Organization (WHO) on the 23^rd of March 2014 and since then it has transformed into an unprecedented and severe epidemic affecting the three countries of West Africa (Guinea, Liberia and Sierra Leone) and lasting for seventeen months (Baize et al., 2014). The name of the causative agent, Ebola, has for a long time instilled fear and anxiety, not just in the endemic areas of Africa, hardest hit by this virus, but also around the world. Since the start of the epidemic, people’s awareness of the impact of the Ebola virus infection became even more acute as it became obvious that the virus could be spread by air travel. The emergence of this lethal virus in a setting of profound poverty, a dysfunctional public-health system and a weak government infrastructure alarmed the wider world and caused dread from an uncontrollable spread. Mankind witnessed a multitude of human losses, orphaned and abandoned children, uncollected bodies lying on the roads, infected patients wandering outside medical compounds searching for food, decimated medical and nursing staff and social disruption. The emergence of the Ebola virus disease in the low-income countries of West Africa has demonstrated the limitation of the unsupported local efforts, largely reactive, to contain the epidemic. Yet, the initial world response could be summarised in one word: delay.

Unlike previous outbreaks of Ebola in Africa, this epidemic had spread along the roads, reaching villages, towns and the crowded slums of the capitals of all three countries (Baize et al., 2014). Cases of the Ebola virus disease were reported in other countries outside the affected area and with the global movement of people and workforce, there was a real possibility of global spread. During the first half of 2015, the epidemic had spread much faster than the response from the international community. Once the effective surveillance and development of containment systems were put in place, the number of new cases started to drop. Towards the end of 2015, the number of new cases became very low; however even after declaring all three countries Ebola free, sporadic cases still occurred demonstrating the unpredictability of the virus.

The WHO statistics by the 14^th of February 2016 showed that there have been 28,639 registered cases of Ebola virus disease and 11,316 deaths (WHO, 2015). The outbreak of the Ebola virus disease in West Africa has claimed more lives than all previous Ebola outbreaks combined (Centers for Disease Control and Prevention, 2014). The majority of cases were recorded in the three West African countries, Guinea, Liberia and Sierra Leone. However, a limited number of exported cases was confirmed in seven other countries worldwide including: Nigeria, Mali, Senegal, the United States of America, Italy, Spain and the United Kingdom.