The Ebola Virus


A virus is an ultramicroscopic infectious organism that, having no
independent metabolic activity, can replicate only within a cell of another host
organism. A virus consists of a core of nucleic acid, either RNA or DNA,
surrounded by a coating of antigenic protein and sometimes a lipid layer
surrounds it as well. The virus provides the genetic code for replication, and
the host cell provides the necessary energy and raw materials. There are more
than 200 viruses that are know to cause disease in humans. The Ebola virus,
which dates back to 1976, has four strains each from a different geographic area,
but all give their victims the same painful, often lethal symptoms.
The Ebola virus is a member of a family of RNA viruses known as ‘
Filoviriade\' and falling under one genus, ‘Filovirus\'. "The Ebola virus and
Marburg virus are the two known members of the Filovirus family" (Journal of the
American Medical Association 273: 1748). Marburg is a relative of the Ebola
virus. The four strains of Ebola are Ebola Zaire, Ebola Sudan, Ebola Reston,
and Ebola Tai. Each is named after the geographical location in which it was
discovered. These filoviruses cause hemorrhagic fever, which is actually what
kill victims of the Ebola virus. Hemorrhagic fever as defined in Mosby\'s
Medical, Nursing, and Allied Health Dictionary as, a group of viral aerosol
infections, characterized by fever, chills, headache, malaise, and respiratory
or GI symptoms, followed by capillary hemorrhages, and, in severe infection,
oliguria, kidney failure, hypotension, and, possibly, death. The incubation
period for Ebola Hemorrhagic Fever ranges from 2-21 days (JAMA 273: 1748). The
blood fails to clot and patients may bleed from injections sites and into the
gastrointestinal tract, skin and internal organs (Ebola Info. from the CDC 2).
The Ebola virus has a tropism for liver cells and macrophages, macrophages are
cells that engulf bacteria and help the body defend against disease. Massive
destruction of the liver is a hallmark feature of Ebola virus infection. This
virus does in ten days what it takes AIDS ten years to do. It also requires
biosaftey level four containment, the highest and most dangerous level. HIV the
virus that causes AIDS requires only a biosaftey level of two. In reported
outbreaks, 50%-90% of cases have been fatal (JAMA 273: 1748).
Ebola can be spread in a number of ways, and replication of the virus
occurs at an alarming rate. Ebola replication in infected cells takes about
eight hours. Hundreds to thousands of new virus particles are then released
during periods of a few hours to a few days, before the cells die. The several
cycles of replication occur in a primate before the onset of the fever and other
clinical manifestations (Ornstein, Matthews and Johnson 7). In most outbreaks,
transmission from patient to patient within hospitals has been associated within
the reuse of unsterile needles and syringes. High rates of transmission in
outbreaks have occurred from patients to heath-care workers and to family
members who provide nursing care without appropriate precautions to prevent
exposure to blood, other body fluids, vomitus, urine and stool. Risk for
transmitting the infection appears to be highest during the later stages of
illness, which are often characterized by vomiting, diarrhea, shock, and
frequently hemorrhaging (JAMA 274: 374). Even a person who has recovered from
the symptoms of the illness may have the virus present in the genital secretions
for a brief period after. This makes it possible for the virus to be spread by
sexual contact. Complete recovery is reached only when no particles of the
virus are left in the body fluids, this however is rarely attained. The disease,
for humans, is not airborne, capable to be passed on through air travel, but for
nonhuman primates it has been a possibility in a few cases.
Ebola Zaire was identified in 1976 in Northern Zaire and was the first
documented appearance of the virus. This strain of the virus effects humans and
nonhuman primates. Close contact and dirty needles spread the Ebola virus. The
center of the epidemic in Zaire involved a missionary hospital where they reused
needles and syringes without sterilization. Most of the staff of the hospital
got sick and died. This outbreak infected 318 with a death rate of 93% (Le
Guenno et al. 1271). Another fatal case was reported one year later in Zaire
but nothing major ever became of it. The most recent case recorded was the
infamous breakout in Kikwit, Zaire. This breakout had the world in an uproar
about the possibility of this virus spreading out globally. This outbreak
appeared to have started with a patient