Global Epidemiology of Ebola Disease: A Review of the West African Outbreak

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 bush meat, 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
compares 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 approved cure for
EDV, only supportive and experimental treatment and a currently FDA approved vaccine from Merck
& Co’s. There are ongoing trials on the following vaccinations: ZMapp, TKM-Ebola, Favipiravir, cAd3,
rVSVΔG-ZEBOVGP12, REGN-EB3 and mAb-114. This review article will attempt to summarize the
current state of understanding on EVD and explore the most recent and accepted information
including the epidemiology of the disease, etiology and pathophysiology, transmission, prevention and
control, history, recent outbreaks in West Africa, clinical manifestations, screening and diagnosis, and
treatment and clinical trials.