Ebola: Background
Ebola (Zaire ebolavirus) is a new and emerging zoonotic disease that originated in the African continent (“Ebola”). Previously known as hemorrhagic fever, it is a mutation of a animal disease; more than 70% of all pathogens start as a zoonotic disease. This virus is highly contagious and very deadly. It spreads through human to human contact; bodily fluid is its means of transmission. Those who become infected suffer from vomiting, diarrhea, and bleeding from orifices. These symptoms place any caretakers at risk of becoming infected even with the proper protective equipment. The individuals most vulnerable to contracting the disease are those in remote regions on the world where Ebola is found in animals. Ebola is a virus, so it survives by transmitting from host to host mutating as much as possible to try and survive (Spillover). There have been several outbreaks in the past forty years; this is largely to due with an increasingly globalized world. Many wonder where Ebola genetically came from and how it progressed to be the deadly from that it currently is in. Current research has been able to answer some of these questions however, there is still much to learn about the virus.
Ebola was first discovered in 1976 in the Democratic Republic of the Congo near the Ebola river. There are 5 species of Ebola virus, 4 of which have caused disease in humans: Zaïre ebolavirus (EBOV), Sudan ebolavirus (SUDV), Tai Forest (TAFV) (formerly known as Ebola Ivory Coast), Bundibugyo ebolavirus (BDBV), and the fifth species, Reston ebolavirus (RESTV). After exposure to the virus, the incubation period can last from 2 – 21 days. Symptoms start as a quick onset of illness: fever, body aches, weakness, vomiting, and diarrhea. It can be difficult to diagnose in early stages due to generic symptoms. The difficult diagnosis usually is how outbreaks begin; many health care providers come in contact with the patient not knowing how contagious they are. Treatment efforts are futile due to the nature of the virus; oral rehydration, electrolytes, and maintaining oxygen levels are the most effective on restoring a patient’s health. These primitive treatments can help a patient but are not full proof and do not have high rates of success. The mortality rate can range from 50- 90% of those who become ill. The best means of prevention is avoiding exposure, however many of the patient zeros in outbreaks know nothing of the illness. If health care providers are in contact with the infected they must be dressed and donned in full personal protective equipment (PPE) (Overview).
Ebola: Genetic Origins
It is believed by many that the virus jumped from a non human primate source which suggests that monkeys are the original animal reservoir. However, there is evidence that fruit bats have been able to easily transmit the disease to humans, as well as primates. Studies shave shown that primates are not the initial animal reservoir of the disease, they are an just an unintended carrier for the virus. Which now brings into focus if the different type of fruit bats are the source. In regions of the original outbreaks, bushmeat is commonly eaten and fruit bats are a delicacy to the culture. Both of which animals sources are carrier for the Ebola virus. In the past if a small village was infected with Ebola from animal contact it would die off since the villages were very isolated. Access to bigger cities and more people now puts the infected bushmeat in a powder keg. The virus can be cooked if exposed to a high enough temperature and smoke inhalation however, this method should be relied upon to fully purify the meat. This is the reason outbreaks occur so frequently in many parts of the African Continent (Keneally).
It has been difficult for scientist with the CDC, WHO, and other health organizations to identify the origins of the virus due to the several strains of that have been discovered. Among the stains there are various zoonotic carriers. The genome of the disease replicates so quickly in a host that there can become up to 50 mutations within one outbreak. This makes it near impossible to take samples from a host and find the original strain (Genetics). As stated by the article on evolution, “Ebola’s high mutation rate and rapid rate of replication combine to allow it to evolve quickly. High mutation rates generate lots of genetic variation for evolutionary processes to work on. And short generation times mean that processes like natural selection and genetic drift can sort through that variation and cause evolutionary change on timescales that are short in human terms” (Ebola and Evolution). In more recent outbreaks in 2014, researches from Harvard studied the genome of the virus in patients. The article stated, “The researchers sequenced 99 Ebola virus genomes collected from 78 Ebola patients in Sierra Leone during the first 24 days of the outbreak. (Some patients contributed samples more than once, allowing researchers a clearer view into how the virus can change in a single individual over the course of infection.) The team found more than 300 genetic changes that make the 2014 Ebola virus genomes distinct from the viral genomes tied to previous outbreaks. They also found sequence variations indicating that the present outbreak started from a single introduction into humans, subsequently spreading from person to person over many months” (Mason). There are far too many mutations for researchers to begin to piece together where this virus comes from. Even with the extensive research from countless sources, there has been no conclusive evidence to point to a particular animal reservoir as the source of the virus.
Ebola: Mutation Threat
There has been a effort to try to share as much genetic information gathered by the many researches as an attempt to try to understand this virus. So far, all attempts have been futile because there are too many mutations that occur with every outbreak. Since the virus has the ability to mutate so rapidly and so diversely, there is concern by some that it could mutate to a more deadly form of itself. For example, there has been thoughts that if the virus could mutate itself to be transmissible through airborne particles while maintaining its current mortality rate, the results would be worse than that of the Black Death. There would effectively be no way to stop the spread especially since the incubation period of the disease can last up to 21 days. But many scientist assure the public this can’t happen. As Harvard University researches stated, “For Ebola to become airborne, it would first have to infect the respiratory system – cells in the throat or lungs [8]. This change alone would likely require a number of mutations. Mutations occur in individuals in a population, and if one individual or a small subset of individuals is better at surviving under some condition than the others, the mutation will become more prevalent. Thus, even if one of the many copies of Ebola in an infected individual were to gain mutations that, in theory, made it airborne, that mutant would have to be at an advantage compared to un-mutated Ebola in order for it to become dominant. Since Ebola virus is spread efficiently as is, the selective pressure for it to become airborne is likely minimal” (Understanding Ebola Fears & Viral Mutations). The disease is transmitting itself to new hosts easily enough for a mutation of such as a airborne transmissible strain not to occur. While some scientist say that the threat of transmission by air particles is not something to be concerned over there is an argument for any standpoint because there is no way to tell what it could mutate to. Since there is no conclusive evidence to support that it will mutate into an airborne related disease, this threat is not relevant at this time.
Ebola: Conclusion
The search for the genetic origin of Ebola has turned up inconclusive thus far. Ebola has affected the lives of many around the world and will continue to do so until a means of combating the disease is found. While the genetic origins of the virus continue to be a mystery It is clear that this will be a daunting task to find the zoonotic reservoir due to the nature of the virus and how quickly and extensively it mutates. They are on the right track keeping different primates and fruit bats under further investigation to see if the disease came from either one of those two species. If researchers can pinpoint the original animal reservoir, there will be a turning point in truly understanding the virus and figuring out if it can be cured or vaccinated against. Until then, many more will suffer and die from this horrible disease. Medical officials can only hope that the virus does not mutate into something more deadly. Researches will not stop until Ebola does; the sheer amount of research being conducted on the disease is proof of it. We can only hope they are successful so we can make the world a safer place.
Works Cited
“Ebola (Ebola Virus Disease).” Centers for Disease Control and Prevention. Centers for Disease
Control and Prevention, 18 Feb. 2016. Web. 25 July 2017.
“Ebola: Overview, History, Origins and Transmission.” GOV.UK. N.p., n.d. Web. 25 July 2017.
Ebola and Evolution. N.p., Oct. 2014. Web. 26 July 2017.
“Genetics of the 2014 Ebola Outbreak.” National Institutes of Health. U.S. Department of Health and Human Services, 15 May 2015. Web. 25 July 2017.
Keneally, Meghan. “How Ebola Emerged Out of the Jungle.” ABC News. ABC News Network, 28 July 2014. Web. 25 July 2017.
Mason Harvard Correspondent, Edward, Liz Mineo, Harvard Staff Writer, Alvin Powell, Harvard
Staff Writer, Christina Pazzanese, Harvard Staff Writer, and Amy Roeder, Harvard Chan School Communications. “Ebola Genomes Sequenced.” Harvard Gazette. N.p., 28 Aug. 2014. Web. 27 July 2017.
Spillover – Zika, Ebola & Beyond. PBS, 2 Aug. 2016. Web. 20 July 2017.
“Understanding Ebola Fears & Viral Mutations.” Science in the News. N.p., 07 Jan. 2015. Web. 27 July 2017.