Ebola VirusCase Study
The
former Soviet Union had an active state-supported bio-weapon research and
production program from the 1970s through the mid 90’s. One branch of the
program was called VECTOR- the State
Research Center
1) What are the potential benefits of
American aid to convert VECTOR’s bioweapon facilities to peaceful research?
What are the potential hazards?
VECTOR
is a level 4 biosafety lab designed for the purpose of creating genetically
altered viruses. According to the Dallas Observer, 2000, “[In 1998], “the U.S. government approached UT Southwestern Medical
Center with the idea of forming a collaborative effort between Dallas and
Siberia [VECTOR] aimed at developing a vaccine against Ebola . The U.S. Defense Department, in fact, is not only paying
for the experiment, but now directly funds the operations of VECTOR in Russia” (3).
There are several benefits and hazards which come as a result of this venture.
Scientists are able to retain their jobs and increase scientific knowledge and
research in this field, thereby reassuring the U.S.
that their knowledge and expertise of biological weapons will not fall into the
wrong hands. The US will be at the forefront
of and be able to indulge in any breakthroughs made. U.S. Aid assists in
strengthening ties and diplomacy between US and Russia .
However, with increased trust, comes increased complacency. There are four
other weapons labs in Russia which go
unchecked and without inspection. Additionally, according to Miller, 2004, at
the time of the accident involving the female employee, VECTOR claimed that the
research was being funded by an outside party but refused to identify their
benefactor or state the nature of the research(2). It may also be difficult to
very whether or not some former soviet scientists are using the American
supported research for peaceful purposes. There seems to be an overall lack of
accountability and that may cause strain on this relatively new relationship in
the future.
2. What tissue(s) does the pathogen
damage that leads to hemorrhaging?
Infection by Ebola virus mimic nonspecific flu-like symptoms
such as fever, myalgia, and malaise(8).
Patients with progressed cell damage and infection exhibit severe
bleeding and coagulation abnormalities, including gastrointestinal
bleeding, rash, and a range of hematological irregularities, such as
lymphopenia and neutrophilia(18). When the
immune system is fighting against this viral pathogen, cytokines signal immune
cells such as T-cells and macrophages to travel to the site of Ebola virus infection (15). The immune cells are
activated by cytokines, stimulating them to produce more cytokines. The
products are then released to interact with the virus. This rapid influx of
immune cells contributes to an exaggerated inflammatory immune response which
is actually damaging to the tissues infected with virions.
Damage to the liver, combined with
massive viremia, leads to disseminated intravascular coagulopathy (14). If
the infection progresses in virulence the virus will enter microvascular
endothelial cells. Extensive damage by the infiltration of immune cells leads
to the terminal stages of Ebola virus infection, which usually include
diffuse bleeding, and hypotensive shock accounts for many Ebola virus fatalities.
3) How could you have
prevented this outbreak from spreading to other scientists at VECTOR?
To
prevent this outbreak from spreading to others in the lab, initially, the
infected individuals should be isolated to limit direct contact with others.
Then, contaminated and waste products should be disposed of properly. It’s
important to ensure that all the used equipments were disposed or sterilized,
disinfecting those that had needed to be reused by others. Communication with
the employees and staff about the nature of the situation is another key method
in order to have them take any and all precautionary measures (1).
4) How is this virus transmitted? What
precautions need to be taken when working with this deadly virus?
The
Ebola Virus is transmitted from person to person by
intimate contact with infected blood, secretions, organs, or semen (19). The
infectious virus within a host can transmit to others as long as the virus
components remain within the blood stream (19). In
the early stages, Ebola may not be highly contagious. Contact with
someone in early stages may not even transmit the disease. As the illness
progresses, bodily fluids from diarrhea, vomiting, and bleeding represent an
extreme biohazard(16).The infection of human cases with Ebola virus has been documented through the handling
of infected chimpanzees, gorillas, and forest antelopes, both dead and alive,
as was documented in Côte d'Ivoire, the Republic of Congo and Gabon(18). The
transmission of the Ebola Reston strain through the handling of
cynomolgus monkeys has also been reported (15).
Caution
must be taken even after a patient recovers from the symptoms of this virus.
The infected person can transmit the virus to others even after they have fully
recovered from illness. Although airborne transmission of Ebola virus is probable,
there is no direct evidence of this hypothesis (8).
Health care workers are commonly infected while treating Ebola patients. These workers often must be in close
contact with infected patients and infected equipment. The identification and
the isolation of virus infected patients is critical and must follow barrier
nursing procedures to prevent the rapid spread of this highly contagious
pathogen. In countries where sanitation and sterile techniques are not enforced
or are simply unattainable, transmission of the virus via basic care techniques
is common.
Burial
ceremonies where mourners have direct contact with the body of the deceased
person can play a significant role in the transmission of Ebola (17). Airborne transmission between monkeys has been observed by
an accidental outbreak in a laboratory located in Virginia ,
USA .
5) What is currently believed to be the
animal reservoir of Ebola virus?
It
has been shown that the initial Ebola infections of humans on the African continent
have occurred due to direct contact with the carcasses of gorillas,
chimpanzees, monkeys, and forest antelopes found dead in the rainforest (8).
Even though the source of infection for humans has been non-human primates, the
fact that these species had a high mortality means they are not the reservoir
for the virus (11). Other species of living organisms, such as plants, birds,
and arthropods have been considered as reservoirs as well; however, more current
evidence points at bats as the carrier for this deadly virus (10).
During
the human epidemics in 2001 and 2003, Ebola
virus was detected in the carcasses
of gorillas, chimpanzees, and duikers (7).
During these outbreaks, researchers from French Research Institute for
Development (IRD) surveyed more than 1,000 small vertebrates in areas that were
in close proximity of carcasses of infected animals (7).After analyzing their
data, IRD researchers were the first to officially identify bats as a potential
reservoir of Ebola virus. They found the genetic sequences of Ebola virus or evidence of an immune response to the
virus in three species of fruit bats: Hypsignathus monstrosus, Epomops
franqueti and Myonycteris torquata (7). More specifically, Ebola RNA sequences were detected in the liver and
spleen of these animals, and antibodies against one of the four subtypes of Ebola was detected in their serum. The bats did not show symptoms of infection
and did not develop the disease. This fact implies that these animals are a
potential reservoir for Ebola virus (7).
Evidence has also shown that the large primates had
the highest mortality rate throughout the dry season during which there is a
lot of food competition between species due to resource deficiencies (7). In
this period, species are in closer contact because of scarce food resources and
could get contaminated more easily. Furthermore, it has been known that the immune function
in bats is somehow modified during the dry season, which provides the virus
with more favorable conditions to reproduce (7).
In
this proposal, bats are more likely to pass the virus onto great apes,
including gorillas and chimpanzees, which have had a high mortality rate (7).
Also, bats could infect humans directly, especially since one of the species of
the discovered bats are often caught and eaten by people who live in
epidemic-prone regions (7, 10). Despite the discovery of these bats as the
potential reservoir for Ebola virus, extensive ecological investigations are
still underway in the Republic of Congo and Gabon to further confirm the
reservoir for this deadly virus.
6) Compare this pathogen with smallpox
as a potential bioweapon. Which could be more dangerous as a weapon of mass
destruction?
Biological
weapons (BWs) deliver toxins and microorganisms, such as viruses and bacteria,
and aim to deliberately inflict disease among people, animals, and agriculture
(6). Several viruses have been identified as dangerous pathogens that can be
used as bio-weapons during wars. Smallpox (variola virus) and Ebola virus are both among the category one, the
most dangerous, agents in the classification system by the Centers for Disease
Control and Prevention (CDC). That means they are among the agents that can be
easily transmitted, have high potential for mortality, create great public
panic, and require public preparedness (6). If a transmissible agent, such as
the smallpox or Ebola virus, infects someone at the site of its
release, that individual could travel and spread the agent to others. This
would result in secondary infections at areas other than the original location
(6). According to an article published by National Center for Infectious
Diseases, an agent must have several qualities to be used for mass destruction.
It should be lethal and producible in large quantities. It should be
communicable from person to person, and there should not be treatments or
vaccines for the developing disease (5). Even though both Ebola virus and smallpox
virus can both be turned into bio-weapons, smallpox poses a greater danger in
terms of mass destruction.
Ebola virus infection causes sudden sever onset of
symptoms, has a short incubation period, and causes death within several days
(8). Therefore, individuals infected with this virus may die before they can
transmit the disease to other individuals. This results in outbreaks that burn
out quickly (12). Smallpox, on the other hand, has a longer incubation period
between contraction and the first obvious symptoms of the disease (12-14 days).
The patient is not contagious until the first symptoms arrive, however, the
initial symptoms could usually be vague and flu-like (13). Smallpox can develop
into two major forms: variola major and variola minor, with 30% and 1% rates of
fatality, respectively. This disease could also occur in two rare forms of
hemorrahgic and malignant, which are both almost always fatal (13). It has been
shown that the Zaire subtype of Ebola virus has killed 80% of its victims (7).
There is not any
evidence that suggests transmission of Ebola
virus between humans through the
air. However, smallpox can be aerosolized, and since it’s a relatively stable
virus, it could remain infective at least several hours if there is no sunlight
or UV light exposure (5,6,13). This transmission through air makes this virus
more communicable between individuals, and adds to its contagiousness. This
virus can also be produced in a large scale (5). Smallpox virus infection can
spread in any climate or season, while that of the Ebola infection has higher
mortality rates during certain periods (5). The fact that smallpox can be
easily transmitted between individuals poses a great risk. The natural host for
variola virus is humans, unlike that for Ebola
virus, which seems to be animals
(fruit bats) (13).
At this time,
there is no vaccine or treatment available for the disease developing from Ebola virus infection (1), and this could make this
a dangerous pathogen as a bio-weapon. However, it should be noted that the
vaccine that was developed against smallpox in 1967 has not been routinely
provided since 1972 in the U.S., due to the fact that the risk for this disease
became minimal (5). Moreover, there is no effective treatment for smallpox.
This virus was finally eradicated in 1979 from the world. At this point, the
survey by World Health Organization (WHO) reveals the availability of
approximately 90 million doses of stored smallpox vaccine worldwide; however,
the viability and storage conditions and are not known (13). It’s been
determined that the vaccine will work it it’s administered up to 4 days after
the viral exposure (13). This period is short since most serious symptoms will
not show by this time. This extreme limit on smallpox vaccine makes this virus
a dangerous pathogen.
Another important
point with smallpox patients is that they would not die quickly. Therefore,
their need for isolated rooms in the hospital, disposable equipments,
medications, and healthcare providers is a long-term requisite (5). During an
outbreak, managing these tasks could be quite a difficult task, which not only
poses financial cost, but can also increase the risk of transmission of
infection to other healthy individuals during hospitalization.
References
1)
Adamcek, K., Eanes, M., Shaw, S., Virology
Project: Ebola Virus. Retrieved: 11/8/07
http://www.biosci.ohiou.edu/virology/Ebola
2) Miller, J. Russian
Scientist Dies in Ebola Accident at Former Weapons Lab. The New York Times. Published: 5/25/2004.
Retrieved: 11/12/2007
http://query.nytimes.com
3) Pappalardo, J.
From Russia, with bugs [US subsidizing Russian Biological Warfare Lab]. Dallas Observer. Published: 6/22/2000.
Retrieved: 11/14/07
http://freepublic.com
4) “Biological Warfare.”
Wikipedia: The Free Encyclopedia. Retrieved: 11/12/07
www.wikipedia.org
5)
Emerging Infectious Diseases.
National Center for Infectious Diseases. Vol. 5, No.4, July-Aug 1999. Retrieved
11/8/07
http://www.cdc.gov/ncidod/eid/vol5no4/pdf/v5n4.pdf
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Tanna, J.H, Preventing “Dark Winter”-The
Public Health System’s Role in Strengthening National Security. Vol. 1,
No.4, Spring 2002. Retrieved 11/8/07 http://www.carnegie.org/reporter/04/preventing/index.html
7)
Leroy, E., Fruit Bats a Reservoir for Ebola Virus. Indigo Base, IRD. November 2005.
Retrieved 11/8/07 www.ird.fr/us/actualities/fiches/2005/fiche231.htm
8)
World Health Organization. Ebola Haemorrhagic Fever. Retrieved
11/8/07
http://www.who.int/mediacentre/factsheets/fs103/en/
9)
Hoenen et al. Ebola Virus: Unravelling Pathogenesis to Combat a
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10)
Leroy, EM, Kimulugui, B, Pourrut, X et al. Fruit Bats as Reservoirs of Ebola Virus. Nature. 2005. 438:575–576
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Pourrut, X, Kumulungui, B, Wittmann, T et al. The Natural History of Ebola Virus in Africa. Microbes and Infection.
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Retrieved 11/11/07
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World Health Organization. Smallpox. Retrieved
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www.biomedcentral.com/1471-2180/3/6/figure/F3
www.biosci.ohiou.edu/virology/Ebola /Dectec3.jpg
(Courtesy
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17)
World Health Organization
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18)
Leroy, Eric M., et al. Multibple Ebola Virus Transmission Events and Rapid Decline of
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19)
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