The Ebola Virus


INTRODUCTION

The most deadly killers on this earth are too small to see with the
naked eye. These microscopic predators are viruses. In my report, I will
answer many basic questions concerning one of the fastest killing viruses, the
Ebola virus. Questions such as "How does it infect its victims?", "How are
Ebola victims treated?", "How are Ebola outbreaks controlled?" and many others
related to this deadly virus.

GENERAL INFORMATION

The Ebola virus is a member of the negative stranded RNA viruses known
as filoviruses. There are four different strains of the Ebola virus - Zaire
(EBOZ), Sudan (EBOS), Tai (EBOT) and Reston (EBOR). They are very similar
except for small serological differences and gene sequence differences. The
Reston Strain is the only one which does not affect humans. The Ebola virus
was named after the Ebola river in Zaire, Africa after its first outbreak in
1976.

STRUCTURE

When magnified by an electron microscope, the ebola virus resembles long
filaments and are threadlike in shape. It usually is found in the form of a "U-
shape". There are many 7nm spikes which are 10nm apart from each other visible
on the surface of the virus. The average length and diameter of the virus is
920nm and 80nm. The virons are highly variable in length (polymorphic), some
attaining lengths as long as 14000nm. The Ebola virus consists of a helical
nucleocapsid, which is a protein coat and the nucleic acid it encloses, and a
host cell membrane, which is a lipoprotein unit that surrounds the virus and
derived form the host cell\'s membrane. The virus is composed of 7 polypeptides,
a nucleoprotein, a glycoprotein, a polymerase and 4 other undesignated proteins.
These proteins are synthesized by mRNA that are transcribed by the RNA of the
virus. The genome consists of a single strand of negative RNA, which is
noninfectious itself. The order of it is as follows: 3\' untranslated region,
nucleoprotein, viral structured protein, VP35, VP40 glycoprotein, VP30, VP24,
polymerase(L), 5\' untranslated region. HOW IT INFECTS

Once the virus enters the body, it travels through the blood stream and
is replicated in many organs. The mechanism used to penetrate the membranes of
cells and enter the cell is still unknown. Once the virus is inside a cell, the
RNA is transcribed and replicated. The RNA is transcribed, producing mRNA which
are used to produce the virus\' proteins. The RNA is replicated in the cytoplasm
and is mediated by the synthesis of an antisense positive RNA strand which
serves as a template for producing additional Ebola genomes. As the infection
progresses, the cytoplasm develops "prominent inclusion bodies" which means that
it will contain the viral nucleocapsid that will become highly ordered. The
virus then assembles and buds off from the host cell, while obtaining its
lipoprotein coat from the outer membrane. This destruction of the host cell
occurs rapidly, while producing large numbers of viruses budding from it.

WHAT IT INFECTS

The Ebola virus mainly attacks cells of the lymphatic organs, liver,
kidney, ovaries, testes, and the cells of the reticuloendothelial system. The
massive destruction of the liver is the trademark of Ebola. The victim looses
vast amounts of blood especially in mucosa, abdomen, pericardium and the vagina.
Capillary leakage and bleeding leads to a massive loss in intravascular volume.
In fatal cases, shock and acute respiratory disorder can also be seen along with
the bleeding. Numerous victims are delirious due to high fevers and many die of
intractable shock. SYMPTOMS

During the onset of Ebola, the host will experience weakness, fever,
muscle pain, headache and sore throat. As the infection progresses, vomiting
(usually black), limited kidney and liver function, chest and abdominal pain,
rash and diarrhoea begin. External bleeding from skin and injection sites and
internal bleeding from organs occur due to failure of blood to clot.

TRANSMISSION

How "patient zero" (first to be infected) acquires natural infection is
still a mystery. After the first person is infected, further spread of Ebola to
other humans (secondary transmission) is due to direct contact with bodily
fluids such as blood, secretions and excretions. It is also spread through
contact with the patients skin which carries the virus. Spread can be
accomplish either by person to person transmission, needle transmission or
through sexual contact. Person to person transmission occurs when people have
direct contact with Ebola patients and do not have suitable protection. Family
members and doctors who contract the virus usually obtain it from this type of
transmission. Needle transmission occurs when needles, which have been used on
Ebola patients, are reused. This happens frequently in developing countries
such as Zaire and Sudan because the heath care is underfinanced. A lucky person
who has