Understanding the 2013-2015 Ebola Outbreak

Background: The 2013-2015 Ebola outbreak caused severe human suffering and a global health crisis. Ebola Virus (EBOV) is a naturally zoonotic RNA virus that has several immune-evasion mechanisms and can cause serious disease and death in humans. The massive impact of the recent epidemic is unique in the 40-year history of this pathogen. Scientists and public health officials around the world are researching the factors that may have contributed to the scale and devastating nature of the 2013-2015 outbreak. Methods: Terms searched online through the McGill library and Medline Ovid included “Ebola”, “immune evasion”, “sequencing”, “Ebola glycoprotein” and “zoonotic transmission”. Only articles published since 2014 were selected. Summary: In this review article, we will provide discussion on the principal factors contributing to the un- usually destructive nature of the 2013-2015 Ebola outbreak. Interestingly, although several nonsynony- mous mutations have been observed in the recently circulating strains, they were not the principal cause of the unusually devastating nature of the outbreak. Instead, the high rate of transmission was likely caused by sociological factors, such as population dynamics and late detection of the outbreak. However, there is evidence to suggest that once the high rate of transmission in humans was established there was selective pressure on the virus to evade the human immune system. This selective pressure may have exacerbated an already deadly outbreak. Ongoing research efforts indicate that there is still much to be discovered about the virus and the control of outbreak management.