Global Epidemiology of EBOLA Disease: A Review

Abstract

EVD is a disease of humans and other non-human primates caused by Ebola viruses, which was first discovered in 1976. Between 1976 and 2013 there had been 24 outbreaks of the disease. The recent outbreak is the 26th and has seen more deaths than all other outbreaks from the disease combined. This outbreak in West Africa occurred in five countries: Guinea, Liberia, Nigeria, Senegal and Sierra Leone. In the present research article, the authors reviewed various studies and current research on EVD. EVD was initially restricted to West Africa when the outbreak was first identified, but later was reported in several countries around the world, including the USA. Researchers have begun to use mathematical analysis from previous outbreaks to construct the Atangana's Beta Ebola System of Equations (ABESE), which is being used to predict the spread of future outbreaks.  The pathophysiology and transmission factors, including the basic and effective reproduction numbers, R0 and Re are discussed in detail. Prevention and control measures, such as proper hygiene techniques (both preventative and post-exposure), education (including educating communities on proper burial techniques), reduction in the consumption and exposure to bushmeat, and controlled prevention of the spread of the disease (proper personal protective equipment and protocol upon exposure or in high-risk environments), are outlined. The history and current outbreak are reviewed in detail, which compare the differences in previous outbreaks compared to the current. Earlier (and less deadly) outbreaks have also been traced to the ZEBOV strain, and researchers suggest that the evolutionary rate of gene mutations was accelerated in this current outbreak. Death occurs in approximately 40% of affected individuals within 7-12 days after the onset of initial symptoms and is most often associated with multi-organ failure. Researchers outline the WHO’s criteria for screening and diagnosis, including primary, secondary and entry screening.  There is currently no cure for EDV, only supportive treatment. There are current drug trials on the following vaccinations: ZMapp, TKM-Ebola, Favipiravir, cAd3 and VSVΔ-EBOVGP12. This review article will attempt to summarize the current state of understanding on EVD and explore the most recent and accepted information including epidemiology of the disease, etiology and pathophysiology, transmission, prevention and control, history, recent outbreaks, clinical manifestations, screening and diagnosis, and treatment and clinical trials.