The Ebola virus, a filovirus, a virus whose structure when seen under a microscope resembles that of a worm, is incredibly communicable and can be spread through the air or by contact with contaminated blood. Travel has always been a way of spreading disease around the world and has always been a concern (World Health Organization, 1998). A specific example dealing with the Ebola virus would be the incident in Reston, Virginia. In 1989, scientists looking for a vaccine for the Ebola virus were studying monkeys, imported from the Philippines, isolated in a primate house in a U.S. government testing facility in Reston, Virginia. The monkeys were first injected with Ebola and then with a potential vaccine, however, healthy monkeys not infected with the virus started to exhibit symptoms of the disease. Over seventy percent of the monkeys died. Fearing that the virus had mutated so that it could become airborne, the army was called in to quarantine the site. It was decided that the surviving monkeys would be killed to prevent any further transmission of the disease. Wearing protective airtight suits, a team of scientists entered the monkey house and began killing the remaining monkeys. However, when two of the team members began to exhibit early warning symptoms of Ebola the scientists began to panic and wondered if this was a new type of Ebola that could become airborne and penetrate protective clothing. As it turned out, neither of the team members suffered further illnesses and eventually became well. This new strain of Ebola, called Ebola Reston, can be transmitted through the air, but luckily this strain was deadly only to the monkeys (Preston, 1994). Scientists now know that Ebola has the ability to mutate and is now considered even more dangerous.
Although a virus can neither be considered alive nor dead, it is considered a “life form” and so can be analogous to a species. Ebola has been known to mutate into new strains with new characteristics and abilities such as the Ebola Reston strain (Preston, 1994). Ebola invading the human population in Reston could be analogous to one of an exotic “species”. It would be an example of a “species” addition into an environment in which it was not previously found. When an exotic species is introduced into a new environment there are a number of possible outcomes, but in the case of Ebola the population interaction is one of exploitation. It’s a symbiotic interaction where the virus is considered a parasite and benefits at the expense of the host. Had Ebola been able to leak out into the Reston community it could have entered the human species, mutated so that it could effect human cells, amplified itself, and spread rapidly through the population killing over eighty percent of those it infected. Species additions and their interactions with local organisms can upset the balance in the environment and have long lasting negative effects. By importing animals for studies, like the monkeys in the Reston incident, there is the possibility of introducing a foreign pathogen and altering the balance of environments that have not had exposure to the pathogen. By deforesting the African rainforests, humans are inadvertently introducing Ebola, an exotic “species,” into the human environment which can have unexpected results. Stricter preventive measures should be taken to make sure dangerous pathogens do not travel outside their natural boundaries. Performing tests for these pathogens before possible hosts leave their natural areas would greatly reduce the risk of introducing an unwanted pathogen like the Ebola virus.
In contrast, technologically advanced humans can also be considered an exotic species to the African rainforests, which have been virtual undisturbed for thousands of years. Besides the local pygmy groups that have lived and probably coevolved with other organisms in the depths of the rainforests for hundreds of generations, technologically advanced humans have had no prior exposure to the rainforest biospheres. With the evolution of our modern culture came many technological discoveries such as vaccinations, which have protected us from many diseases once proven lethal to the human race. Also, we have evolved many sanitation practices, which have provided a barrier to germs and illnesses. With these cultural advantages our bodies may have weakened in fighting off germs and viruses it was able to defeat before and in a way may have lost evolutionary adaptations to certain diseases. Therefore pygmy populations of the rainforest, which have had more experience with the Ebola virus, could possibly have evolved ways of fighting of the virus. Interestingly enough, a study performed in 1999 decided to test the “frequency and distribution of filovirus seroprevalence” in pygmy and non-pygmy populations in the Central African Republic (Gonzales et al., 2000). Blood samples taken from both populations were tested for Ebola antibodies. Antibodies were discovered in both groups; however, it was discovered that the pygmy populations had double the amount of antibodies than that of non-pygmies (2000). This brings up a number of interesting possibilities. Pygmy populations that have been living in the same environment in which the Ebola virus is thought to have its reservoir might have evolved a mechanism in which they could coexist with the virus because in order to have antibodies to a virus a population must have experienced the virus in the past. Higher levels of antibodies might mean more contact with the virus and so further research into the histories of these pygmy populations might reveal some interesting discoveries. Further destruction of the rainforests might be diminishing our chances for finding a way of stopping the Ebola virus. Rainforests are believed to hold many undiscovered scientific breakthroughs, especially in the field of medicine, and so by destroying these diverse biological environments, humans are destroying any chance for a possibility of overcoming Ebola.
Although there is no known cure for the Ebola virus, many scientists believe the answer to this problem might be in antibody research. United States Army researchers have recently reported that mice protected by newly developed antibodies did not die when exposed to the Ebola virus (Henderson, 2000). Researchers reported that the antibodies were able to protect the mice when “administered before or after a viral challenge” (2000). However, it was not clear how the antibodies protected the mice from the virus. The antibodies attached to different sites on the virus and according to scientists could have either prevented virus-infected cells from binding to healthy cells or initiated some sort of response from the immune system to fight of the virus. Scientists are also trying to devise a vaccine for the Ebola virus but Yoshihiro Kawaoka, a virologist at the University of Wisconsin-Madison, says “antibodies might mount a more practical defense sine Ebola outbreaks are sporadic” (Seppa, 2000). However, by creating synthetic antibodies are humans altering the course of evolution originally determined by the earth’s environments? The human population might already be too large for the earth to sustain and so the earth might have created a virus such as Ebola to put an end to the human destruction of its environments and resources. Could the human race be the true virus? Are we the parasites that the earth is desperately trying to destroy?
Today, scientists are still searching for a way to control the Ebola virus. They believe that with the discovery of the “reservoir species” new insights could be made into antibody and vaccine research (Kahn, 1996). However, if the rainforest had stayed undisturbed it is very possible that the human species would never had contact with Ebola and that the virus would have continued its life cycles deep within the rainforest as a natural part of the ecosystem. Evidence does show that outbreaks have occurred near factories and developmental areas near newly exposed areas of the rainforests. Alarmingly, Ebola outbreaks have occurred more frequently in the nineties than in the past. The enormous human population has created an imbalance in the environment and so the earth will respond. Humans, with their evolutionary weakened immune systems, would be the ideal hosts for the viruses that the environments of earth have created. Our actions as a species have a direct impact on the balance of nature and if we are not careful enough to keep the environmental balance that the earth took billions of years to establish, we could lead our species to its own demise.
References
Gonzalez, Jean Paul. 2000. Ebola and Marburg virus antibody prevalence in selected populations of the Central African Republic. Microbes and Infection 2: 39-44.
Henderson, C.W. 2000. New monoclonal antibodies combat virus in mice. World Disease Weekly: 2.
Khan, A., Ksiazek, T.G., Mahy, B., Nichol, S.T., Peters, C.J., Rollin, P.E., and Sanchez, A. “Reemergence of Ebola virus in Africa.” Emerging infectious diseases. (July-September 1995).
Oldstone, Michael B. A., 1998. Viruses, plagues, & history. Oxford University Press, New York.
Preston, Richard. 1994. The hot zone. Doubleday, New York.
Seppa, Nathan. 2000. Antibodies fight Ebola virus in mouse test. Science News 157: 150.
Wickelgren, Ingrid. 1998. A method in Ebola’s madness. Science 279: 983-984.
World Health Organization. “Emerging and re-emerging infectious diseases.” WHO information.
