The Deadly Ebola Virus :: Ebola Hemorrhagic Fever (Ebola HF)

The Ebola Virus is the common name for several strains of virus, threeof which argon known to cause hemorrhagic fever in humans, which ischaracterized by massive bleeding and destruction of internal tissues.Named for the Ebola River in Zaire, Africa, where the virus was firstidentified, the Ebola virus be keen-sighteds to the family Filoviridae. common chordstrains of Ebola virus that are often fatal to humans have beenidentified. Named for the areas in which the first recognized outbreakstook place, these strains are referred to as Ebola/Zaire (EBOZ),Ebola/Sudan (EBOS), and Ebola/Tai Forest (EBOT). A fourth Ebola strain,called Ebola/Reston(EBOR), has not been found to cause disease inhumans. As outbreaks of Ebola hemorrhagic fever continue to occur,other strains may be identified. The viruses are long rods, 800 to1000 nanometers (nm) long (1 nm equals one-billionth of a meter, or 4 x10-8 in), but particles as long as 14,000 nm have been seen. each virusconsists of a coiled strand of ribonucleic acid (RNA) contained in anenvelope derived from the boniface cell membrane that is covered with 7 nmspikes placed 10 nm apart visible on the surface of the virion (Figure1). When magnified several thousand times by an electron microscope,these viruses have the appearance of long filaments or threads but theparticles are pleomorphic, meaning they can exist in many shapes. Theirbasic structure is long and filamentious, essentially bacilliform, butthe viruses often takes on a U shape (Figure 2). They contain aunique single-stranded molecule of noninfectious (negative sense ) RNA.The virus is composed of 7 polypeptides, a nucleoprotein, aglycoprotein, a polymerase and 4 other undesignated proteins. Proteinsare produced from polyadenylated monocistronic mRNA a speciestranscribed from vi genomes. As the infection progresses the cytoplasm of the infected cell develops prominent inclusion bodies which contains the viralnucelocapsid, which will become highly structured. The virus thenassembles, and buds off the host cell, attaining its lipoprotein coatfrom the infected cells outer membrane. The replication in anddestruction of the host cell is rapid and produces a large number ofviruses budding from the cell membrane. Symptoms Cases of Ebola haveoccurred in isolated instances and in outbreaks in sub-Saharan Africa.A important problem in diagnosing the disease is that the virusesoften strike in remote areas of developing countries, where access tolaboratories for specimen analysis is limited. Of all the Ebolastrains, Ebola/Zaire is the virtually dramatic and deadly. The Ebola viruscauses hemorrhagic fever, which is characterized by such symptoms assevere headache, weakness, and muscle aches, followed by vomiting,