One year into the Ebola epidemic: a deadly, tenacious and unforgiving virus

One year after the first Ebola cases started to surface in Guinea, WHO is publishing this series of 14 papers that take an in-depth look at West Africa’s first epidemic of Ebola virus disease.

UNMEER/Martine Perret

Introduction - This assessment looks at how West Africa’s epidemic of Ebola virus disease has evolved over the past year, giving special attention to the situation in Guinea, Liberia, and Sierra Leone. The success stories in Senegal, Nigeria, and likely Mali are also described to show what has worked best to limit onward transmission of Ebola following an imported case and bring the outbreak to a rapid end. The fact that a densely populated city like Lagos was successful in containing Ebola offers encouragement that other developing countries can do the same.

An overview of how the Ebola outbreak in the Democratic Republic of Congo evolved and was brought under control underscores the many differences between the outbreaks in West Africa and in equatorial Africa, where all previous outbreaks since the first two in 1976 have occurred.

Key events in the WHO's Ebola response are outlined to show how initial control efforts were eventually overwhelmed by the wide geographical dispersion of transmission, the unprecedented operational complexity of the outbreaks, and the many factors that undermined the power of traditional containment measures to disrupt transmission chains. These factors are also described.

In efforts coordinated by WHO, scientists and the pharmaceutical industry have geared up to develop, test, license, and introduce the first Ebola vaccines, therapies, and point-of-care diagnostic tests. As a strong expression of solidarity with the people of West Africa, these groups are attempting to compress work that normally takes two to four years into a matter of months.

Finally, the assessment takes a look at the potential future evolution of the Ebola epidemic. Based on what has been learned during this first year, what critical strategies and interventions will give countries and their partners the best chance of bringing the outbreaks under control?