Docstoc

The Ebola Virus virus is an ultramicrosco

Document Sample
The Ebola Virus virus is an ultramicrosco Powered By Docstoc
					The Ebola Virus                     A virus is an ultramicroscopic infectious organism that, having n
o independent metabolic activity, can replicate only within a cell of another host organism. A viru
s consists of a core of nucleic acid, either RNA or DNA, surrounded by a coating of antigenic protei
n and sometimes a lipid layer surrounds it as well. The virus provides the genetic code for replica
tion, and the host cell provides the necessary energy and raw materials. There are more than 200 vi
ruses 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 l
ethal symptoms.                     The Ebola virus is a member of a family of RNA viruses known as 'Fi
loviriade' 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). Ma
rburg is a relative of the Ebola virus. The four strains of Ebola are Ebola Zaire, Ebola Sudan, Ebo
la 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 grou
p 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 an
d 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 Ebo
la virus infection. This virus does in ten days what it takes AIDS ten years to do. It also requir
es biosaftey level four containment, the highest and most dangerous level. HIV the virus that caus
es AIDS requires only a biosaftey level of two. In reported outbreaks, 50%-90% of cases have been f
atal (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 f
ew days, before the cells die. The several cycles of replication occur in a primate before the onse
t of the fever and other clinical manifestations (Ornstein, Matthews and Johnson 7). In most outbre
aks, transmission from patient to patient within hospitals has been associated within the reuse of u
nsterile 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 t
he 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 r
ecovered 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 i
s rarely attained. The disease, for humans, is not airborne, capable to be passed on through air tr
avel, but for nonhuman primates it has been a possibility in a few cases.                    Ebola Zai
re was identified in 1976 in Northern Zaire and was the first documented appearance of the virus. T
his strain of the virus effects humans and nonhuman primates. Close contact and dirty needles sprea
d the Ebola virus. The center of the epidemic in Zaire involved a missionary hospital where they re
used needles and syringes without sterilization. Most of the staff of the hospital got sick and die
d. 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 rec
orded was the infamous breakout in Kikwit, Zaire. This breakout had the world in an uproar about th
e possibility of this virus spreading out globally. This outbreak appeared to have started with a p
atient who had surgery in Kikwit on April 10, 1995. Members of the surgical team then developed sym
ptoms similar to those of a viral hemorrhagic fever disease (Ebola Info. from the CDC 2). From ther
e, the disease spread to more than 300 others. The most frequent symptoms at the onset were fever (
94%), diarrhea (80%), and server weakness (74%); other symptoms included dysphagia (41%) and hiccups
 (15%). Clinical signs of bleeding occurred in 38% of cases (JAMA 274: 373). The World Heath Organ
ization declared on August 24, 1995 that the outbreak of Ebola Zaire in Kikwit was officially over a
fter killing 244 of its 315 known victims ('Ebola Outbreak Officially Over' 1). This outbreak had a
 rate of death over 75%.                     Ebola Sudan also occurred in 1976 about the same time as E
bola Zaire. The number of cases was 284 with a death rate of 53% (Le Guenno et al 1271). The outbr
eak occurred in a hospital setting. In 1979 a small epidemic was acknowledged in the same town of
Sudan. Of the thirty-four recorded cases there were twenty-two fatalities (Ebola Info. from the CDC
 1). Again the setting for the small epidemic was a hospital setting with inadequate supplies and u
nsanitary conditions.                    Ebola Reston was isolated in 1989 during an outbreak of cynom
olgus monkeys in a quarantine in Reston, Virginia (Le Guenno et al 1271). These monkeys were import
ed to the U.S. from the Philippines. This was the only outbreak of the virus to go outside the conti
nent of Africa. This Reston strain of Ebola appears to be highly pathogenic for some monkey specie
s but not for man (Le Guenno et al 1271). No humans fell victim or even contracted the virus. This
 also is the only known strain to be able to be transferred through the air.
                         Ebola Tai, which was named after the forest in which it was found, is the
newest stain of the Ebola family. A Swiss female zoologist, who performed an autopsy on a chimpanz
ee infected with the same virus in the wild, contracted it. This occurred in the Ivory Coast, West
Africa in mid November of 1994. This is the only know case of Ebola Tai and is the first recorded ca
se that infection of a human has been linked to naturally infected monkeys anywhere on the African c
ontinent. It is also not clear how the chimpanzee may have contracted the disease.
  The usual hosts for these types of hemorrhagic causing viruses are rodents, ticks or mosquitos. T
he natural reservoir for Ebola viruses has not been identified and ... because of the high mortality
  rate seen in apes they are unlikely to be the reservoir (Le Guenno et al 1271). Thousands of anima
ls captured near outbreak areas, are tested for the virus, but efforts have always been unsuccessful
.                   The Ebola might never pose a problem to the world community but, the virus itself
  is armed with several advantages. It has the ability to mutate into new strains as we have seen ov
er time. The fact that there are no know hosts, which means that there is no way to create a vaccine
, coupled with the fact that poor sanitary conditions and lack of medical supplies worsen the spread
ing of the disease, meaning that there could be a slight chance that the virus could probably become
  an international problem.                    Even if an international crisis were to occur, the virus
  has to many downfalls that would over shadow the mass spread of the diseases. First the virus is e
asily destroyed by disinfectants (Ebola Info. from the CDC 3). Also, under ultraviolet light the vi
rus falls apart. This ultraviolet light smashes their genetic material making them unable to replic
ate. Ebola's virulence may also serve to limit its speed: its victims die so quickly that they do n
ot have a chance to spread the infection very far. In order for the virus to become airborne it wou
ld have to mutate in such a way that its outer protective coating of proteins, the capsid, could res
ist the forces to which they are subjected in air, like dryness and heat. It would also probably ne
ed to change structure to allow infection through the respiratory system. There are no exact measur
es of the rate of Ebola mutation, but the probability of the required mutations happening is very lo
w (Ornstein, Matthews and Johnson 4).                          There is no cure or vaccine and it is still u
nclear if blood from survivors that contain antibodies can be used to synthesize a serum to treat th
e disease with. Some patients have had symptoms subside with the transfusion of survivors blood but
  not connection to the antibodies and the relief of the illness was proven. There is a good chance
that a vaccine may never be synthesized. The kind of research needed to develop a modified live vir
us vaccine simply could not be done, given the scope of the problem. That is, only a few people wou
ld be working in labs who would need to be vaccinated, and a vaccine might want to stockpile in the
event of an epidemic. Nevertheless, these are not the scale of circumstances under which the develo
pment of a vaccine could be afforded (Dr. F.A. Murphy 3).
ebola virus virus ultramicroscopic infectious organism that having independent metabolic activity re
plicate only within cell another host organism virus consists core nucleic acid either surrounded co
ating antigenic protein sometimes lipid layer surrounds well provides genetic code replication host
cell provides necessary energy materials there more than viruses that know cause disease humans ebol
a which dates back four strains each from different geographic area give their victims same painful
often lethal symptoms ebola member family viruses known filoviriade falling under genus filovirus ma
rburg known members filovirus family journal american medical association marburg relative four stra
ins zaire sudan reston each named after geographical location which discovered these filoviruses cau
se hemorrhagic fever which actually what kill victims hemorrhagic fever defined mosby medical nursin
g allied health dictionary group viral aerosol infections characterized fever chills headache malais
e respiratory symptoms followed capillary hemorrhages severe infection oliguria kidney failure hypot
ension possibly death incubation period hemorrhagic ranges from days jama blood fails clot patients
bleed from injections sites into gastrointestinal tract skin internal organs info tropism liver cell
s macrophages macrophages cells that engulf bacteria help body defend against disease massive destru
ction liver hallmark feature infection this does days what takes aids years also requires biosaftey
level four containment highest most dangerous level causes aids requires only biosaftey level report
ed outbreaks cases have been fatal jama spread number ways replication occurs alarming rate replicat
ion infected cells takes about eight hours hundreds thousands particles then released during periods
  hours days before several cycles occur primate before onset other clinical manifestations ornstein
matthews johnson most outbreaks transmission patient patient within hospitals been associated within
  reuse unsterile needles syringes high rates transmission outbreaks have occurred patients heath car
e workers family members provide nursing care without appropriate precautions prevent exposure blood
  other body fluids vomitus urine stool risk transmitting infection appears highest during later stag
es illness often characterized vomiting diarrhea shock frequently hemorrhaging jama even person reco
vered symptoms illness have present genital secretions brief period after this makes possible spread
  sexual contact complete recovery reached only when particles left body fluids this however rarely a
ttained disease humans airborne capable passed through travel nonhuman primates been possibility cas
es zaire identified northern zaire first documented appearance strain effects humans nonhuman primat
es close contact dirty needles spread center epidemic involved missionary hospital where they reused
  needles syringes without sterilization most staff hospital sick died outbreak infected with death r
ate guenno another fatal case reported year later nothing major ever became recent case recorded inf
amous breakout kikwit breakout world uproar about possibility spreading globally outbreak appeared s
tarted with patient surgery kikwit april members surgical team then developed similar those viral in
fo there more than others frequent onset were diarrhea server weakness other included dysphagia hicc
ups clinical signs bleeding occurred cases world heath organization declared august outbreak kikwit
officially over after killing known victims officially over rate death over sudan also occurred abou
t same time number with guenno hospital setting small epidemic acknowledged same town sudan thirty r
ecorded there were twenty fatalities info again setting small epidemic setting inadequate supplies u
nsanitary conditions reston isolated during cynomolgus monkeys quarantine reston virginia guenno the
se monkeys were imported philippines outside continent africa strain appears highly pathogenic some
monkey species fell victim even contracted also strain able transferred through named forest found n
ewest stain swiss female zoologist performed autopsy chimpanzee infected wild contracted ivory coast
 west africa november know case first recorded human linked naturally monkeys anywhere african conti
nent clear chimpanzee contracted usual hosts these types causing viruses rodents ticks mosquitos nat
ural reservoir identified because high mortality seen apes they unlikely reservoir thousands animals
 captured near areas tested efforts always unsuccessful might never pose problem world community its
elf armed several advantages ability mutate into strains seen time fact know hosts means create vacc
ine coupled fact poor sanitary conditions lack medical supplies worsen spreading meaning could sligh
t chance could probably become international problem even international crisis occur many downfalls
would shadow mass diseases first easily destroyed disinfectants under ultraviolet light falls apart
ultraviolet light smashes their genetic material making them unable replicate virulence serve limit
speed quickly they chance very order become airborne would mutate such outer protective coating prot
eins capsid could resist forces subjected like dryness heat would probably need change structure all
ow through respiratory system exact measures mutation probability required mutations happening very
ornstein matthews johnson cure vaccine still unclear blood survivors contain antibodies used synthes
ize serum treat some patients subside transfusion survivors connection antibodies relief illness pro
ven good chance vaccine never synthesized kind research needed develop modified live simply done giv
en scope problem people working labs need vaccinated might want stockpile event nevertheless scale c
ircumstances under development afforded murphyEssay, essays, termpaper, term paper, termpapers, term
 papers, book reports, study, college, thesis, dessertation, test answers, free research, book resea
rch, study help, download essay, download term papers

				
DOCUMENT INFO
Shared By:
Categories:
Tags:
Stats:
views:6
posted:12/28/2011
language:English
pages:3