Ebola Virus Disease – A short Introduction

Introduction Ebola is the name of a river situated near the village Yambuku in Congo. Two simultaneous outbreaks of Ebola virus disease were reported in this region in 1976; hence the name Ebola (Kisangani and Bobb, 2009). Ebola virus belongs to the Filoviridae family, and the disease resulting from Ebola virus is considered a Viral Hemorrhagic Fever (VHF) – a label used to refer to a multisystem syndrome in which damage to vascular system occurs which causes hemorrhage that may be life-threatening (Newman, 2015). The main natural reservoirs of viruses that cause VHF are arthropods and rodents. As far as Ebola virus is concerned, bats have been considered to be a major natural reservoir of this virus; the evidence to support this notion is however contradictory (Klenk and Feldmann, 2004). Transmission and Course of Ebola Virus Disease (EVD) During an outbreak, the first individual to be infected with Ebola virus is thought to acquire the infection through direct contact with an animal that harbors the virus (Wilson, 2014). Transmission between humans takes place through direct contact with patient’s body secretions including saliva, blood and semen (Vidal, 2015). A person infected with Ebola virus does not spread the disease until s/he begins to manifest it's symptoms; moreover, spread through the air does not take place (Evans, 2013). Virus may be detected in the semen of patients even after they have recovered; they may transmit the disease 'sexually' up to 9 months after contracting EVD (Oldstone, 2009). The typical course of Ebola virus infection spans over two to three weeks. The initial symptoms of the disease include myalgia, fever and malaise which are interpreted by the patient as ‘a flu-like illness’.

As Ebola virus disease progresses, patients manifest severe bleeding along with coagulation abnormalities (Rubin and Reisner, 2009). Neutrophilia (elevated neutrophil count), lymphopenia (low lymphocyte count) along with a skin rash and gastrointestinal bleeding are commonly observed in such patients. The inflammatory response that develops is not protective and in most cases it is exaggerated. Worsening viremia (viral presence in blood) and the resulting liver damage may result in disseminated intravascular coagulopathy (DIC) – a disorder which results from over activity of proteins that control blood clotting (Ryabchikova and Price, 2004). The integrity of blood vessels is further compromised since the virus directly infects the endothelial cells of blood vessels at this stage. The ultimate outcome of this process is a hypotensive shock that results due to excessive bleeding. Diagnosis, Treatment and Prognosis Confirmation of Ebola virus disease diagnosis based on signs and symptoms is not a possibility. Therefore, tests like ELISA, Polymerase Chain Reaction (PCR), detection of IgM and IgG antibodies and Immunohistochemistry testing are used at various stages of the disease to confirm the diagnosis.

No vaccine for protection against Ebola virus disease is commercially available (Preston, 2012). Many vaccines are however under trials (Phase I-III clinical trials.

Treatment is mainly supportive, which includes administration of intravenous fluids, maintaining balance of electrolytes, oxygen support, maintenance of blood pressure and the treatment of secondary infections (Chertow et al, 2014). An antiviral drug named favipiravir was the first to demonstrate improvement in the condition of patients with low levels of Ebola virus in their blood (Goldsmith, 2016). Ebola infection is associated with an unfavorable prognosis and the mortality rate may be as high as 90%; however, early detection and diagnosis of the disease may bring forth comparatively better outcomes (Lee, 2005). References Chertow, D.S., Kleine, C., Edwards, J.K., Scaini, R., Giuliani, R. and Sprecher, A., 2014. Ebola virus disease in West Africa—clinical manifestations and management. New England Journal of Medicine, 371(22), pp.2054-2057. Evans, A.S., 2013. Viral infections of humans: epidemiology and control. Springer Science & Business Media. Goldsmith, C., 2016. The Ebola Epidemic: The Fight, the Future. Twenty-First Century Books. Kisangani, E.F. and Bobb, S.F., 2009. Historical dictionary of the Democratic Republic of the Congo (Vol. 112). Scarecrow Press. Klenk, H.D. and Feldmann, H., 2004. Ebola and Marburg viruses: molecular and cellular biology. Garland Science. Lee, A.V., 2005. Coping with disease. Nova Publishers. Newman, P., 2015. Ebola: Fears and Facts. Millbrook Press. Oldstone, M.B., 2009. Viruses, plagues, and history: past, present and future. Oxford University Press. Preston, R., 2012. The hot zone: the terrifying true story of the origins of the Ebola virus. Anchor. Rubin, E. and Reisner, H.M. eds., 2009.Essentials of Rubin's pathology. Lippincott Williams & Wilkins. Ryabchikova, E.I. and Price, B.B., 2004. Ebola and Marburg viruses: a view of infection using electron microscopy. Battelle Press. Vidal, Y., 2015. How to Prevent the Spread of Ebola: Effective Strategies to Reduce Hospital Acquired Infections. Lara Publications Inc. Wilson, F., 2014. CDC Guidance on Ebola Virus (EVD): 2014 Edition. International Publications Media Group.


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