FREE ESSAY ON THE EBOLA VIRUS

THE EBOLA VIRUS

The Ebola virus is one of the most deadly viruses that man kind has
ever seen. 
In clinical cases it has a mortality rate of 50%-90%. The Viruses has
many different strains including Marburg, Ebola Zaire, Reston and Sudan,
each named after the location of their first clinical case. They each cause
different symptoms and different mortality rates. Non the less, the
collection of Ebola viruses at the present, pose a serious health threat to
people in undeveloped countries and potentially in developed ones as
well. 
The first documented clinical case of the Ebola virus was in 1967.
Marburg, a strain of the virus was seen in laboratory workers in Marburg,
Germany. The workers had been exposed to tissue and blood from
African green monkeys imported from Uganda. They were to be used as
tests subjects. 25 of the workers were exposed to the virus, 7 died. The
same virus had confirmed cases in Uganda at approximately the same
time. Sporadic instances of the Marburg strain have been reported in
several other African countries since then. The first major outbreak of the
ebola virus was in 1976, in Zaire and in Sudan. "Over 500 cases were
reported, with mortality rates of 88% in Zaire and 53% in Sudan"1 The
cause of these outbreaks still remain unknown. No association with
monkeys could be attributed to either of the outbreaks. The only other
case besides in Marburg that Ebola seemed to be associated with
monkeys was a filovirus (family of viruses containing Ebola) isolated from 
cynomolgus monkeys from the Philippines. This Virus caused no serious
symptoms in humans. Scattered outbreaks of Ebola have been reported
in Central Africa for several years. 
The Ebola virus is a member a family of RNA viruses known as
filoviruses. Ebola is a negative stranded RNA virus. The virus partial has
the shape of a long stand with loops on the end, like worms. There are
variations on this shape, depending on the specific virus. Each virus in the
filovirus family contain a nucleocapsid consisting of a dark central space
surrounded by a helical capsid, the outer protein coat of a cell. A channel
exists in the nucleocapsid. This is where the Nucleic acid (DNA) is
stored. "The viral partical is surrounded by a lipoprotein unit membrane
envelope derived from the host cell plasma membrane. Spikes of
approximately 7nm, spaced at approx 10nm intervals are visible on the
viron surface."- Properties of Viron, Excerpt from virology Cd. 
Once the Virus partical enters the cell it uses the host cells DNA as
material to construct replica ebola virus particals. This is known as a lytic
cycle. The new particals form "inclution bodies": small sites where the
individual particals grow. As the inclusion bodies grow and become more
structured, the cell bursts and the viruses quickly find new cells to infect.
This process is extremely rapid. Ebola is known for it's short incubation
period of 2 to 21 days. 
The method of primary infection with the ebola virus in a natural is
still unknown, 
however secondary transmission occurs through sexual contact and
infected blood samples. Transmission usually occurs between an infected
patient and hospital workers or family members that care for the patient.
The virus has also been transmitted by reusing hypodermic needles in
hospitals where supplies are limited.There is also evidence of respiratory
spread of infection. There was a documented case with the Reston virus
where the virus was spread by droplets of vomit infecting people. This
doesn't mean that the virus is air born it means that direct contact with
contaminated blood can cause infection. "Other area's the virus has been
found in is in throat washes, urine, soft tissue effusates, semen and
anterior eye fluid. It has also been regularly isolated from autoptic
material, such as spleen, lymph nodes, liver and kidney but rarely from
brain or other nervous tissues"- [ Properties of Viron, Excerpt from
virology Cd.} 
The symptoms of Ebola develop 4 to 16 days after initial infection.
"Persons develop fever, chills, headaches, muscle aches, and loss of
appetite. As the disease progresses, vomiting, diarrhoea, abdominal pain,
sore throat, and chest pain can occur. The blood fails to clot and patients
may bleed from injection sites as well as into the gastrointestinal tract,
skin, and internal organs. "- [CDC, http://www.cdc.gov/] The Ebola and
Marburg virus causes sever hemorhagic fever in humans . Between 5 and
7 days sever haemorrhages form on every orifice of the body. Between 7
and 16 days, death occurs either from shock or loss of blood. The
Reston virus causes hemorhagic fever in monkeys but has no serious
effects on humans. The most virulent strand of Ebola is the Ebola Zaire 
virus. This strand of Ebola has the highest mortality rate of the filoviruses. 
At this time there is no cure for the Ebola virus. With the use of new
technology such as recombinant DNA research, we are now able to see
and begin to understand the molecular structure of Ebola and it's
mutations. Virologist are hopeful that the details of virus replication and
virus-host interactions will be uncovered in the near future. By using less
virulent filoviruses such as reston virus, virologists can see how Ebola
works in a slower less destructive form. New tools and new ideas will
also contribute to the advancement of a cure for Ebola. 
Ebola and its closely related viruses are causing deaths all over
undeveloped countries. E bola has one of the highest mortality rates of all
viruses. New research and new ideas will contribute to a cure. Scientists
are hopeful that further outbreaks of Ebola such as Zaire and Sudan can
be avoided As long as simple safety precautions are taken. Hopefully
Ebola will soon take it's place among the defeated viruses of the world. 
Bibliography 
Centers for Disease Control, Ebola research and statistics. 
http://www.cdc.gov/ncidod/publications/brochures/ebolainf.htm 
Marburg and Ebola viruses, Excerpt from the Encyclopedia of Virology
CD-ROM 
http://www.bocklabs.wisc.edu/eov-ebola.html 
World Health Orginization, Emerging and Other Communicable Diseases
(EMC) 
http://www.who.ch/programmes/emc/ebola/ebfact.htm