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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 for Virology and Biotechnology. They worked with pathogens for which there is no known cure. While working to develop a vaccine against Ebola  virus, one of the scientists accidentally stuck herself with a needle contaminated with virus. She contracted Ebola  hemorrhagic fever and died.

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.


1) Adamcek, K., Eanes, M., Shaw, S., Virology Project: Ebola  Virus. Retrieved: 11/8/07   

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

3) Pappalardo, J.  From Russia, with bugs [US subsidizing Russian Biological Warfare Lab]. Dallas Observer. Published: 6/22/2000. Retrieved: 11/14/07 

4) “Biological Warfare.” Wikipedia: The Free Encyclopedia. Retrieved: 11/12/07

5) Emerging Infectious Diseases. National Center for Infectious Diseases. Vol. 5, No.4, July-Aug 1999. Retrieved 11/8/07
6) 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

7) Leroy, E., Fruit Bats a Reservoir for Ebola  Virus. Indigo Base, IRD. November 2005. Retrieved 11/8/07

8) World Health Organization. Ebola  Haemorrhagic Fever. Retrieved 11/8/07

9) Hoenen et al. Ebola  Virus: Unravelling Pathogenesis to Combat a Deadly Disease. Trends Mol. Med. May 2006, 12(5): 206-215
10) Leroy, EM, Kimulugui, B, Pourrut, X et al. Fruit Bats as Reservoirs of Ebola  Virus. Nature. 2005. 438:575–576
11) Pourrut, X, Kumulungui, B, Wittmann, T et al. The Natural History of Ebola  Virus in Africa. Microbes and Infection. 2005. 7:1005–1014

12) Retrieved 11/11/07 _COMPARE/sci_Ebola _COMPARE_01.html#

13) World Health Organization. Smallpox. Retrieved 11/8/07

14) September 2003, p. 9733-9737, Vol. 77, No. 18
15) BMC Microbiology 2003 3:6   doi:10.1186/1471-2180-3-6

16) /Dectec3.jpg
(Courtesy of _cell.htm

17) World Health Organization
Provisional Revision: 2007

18) Leroy, Eric M., et al. Multibple Ebola  Virus Transmission Events and Rapid Decline of Central African Wildlife.  Science 303: 387 -389. 2004

19) Facts sheet: Community Health Administration .html Journal of Virology,
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