Emerging Infectious Diseases: Ebola
History of Emergence of Ebola
Ebola Virus Disease (EVD) is a viral disease that first emerged in 1976 in Nzara, Sudan and Yambuku, Zaire (Lever & Whitty, 2016). During the initial outbreak, over 600 people were suspected to be or had been confirmed infectious and the death rate had nearly reached 90% (Lever & Whitty, 2016). In just 22 weeks the outbreak had been fully contained in these areas (Lever & Whitty, 2016). In 1977, there was one case of EVD in Tandala, Zaire with no further spread (Lever & Whitty, 2016). 1979 brought 34 positive cases back to Nzara, Sudan where the disease had initially emerged (Lever & Whitty, 2016). Throughout the 1980’s and the early 1990’s, news of an EVD outbreak seemed to lie dormant until 1994 when 31 people died from the disease in Gabon (Lever & Whitty, 2016). Since then, outbreaks have been reported every one to four years throughout Central Africa with a total of 22 reported epidemics since 1976 (Lever & Whitty, 2016). In 2014, the first case of EVD was confirmed in the United States in a patient who had traveled from West Africa to Dallas, Texas (“Ebola,” 2017). The two healthcare workers who had cared for the patient were exposed to EVD but recovered later (“Ebola,” 2017). Since 2014, there have been seven people in the United States who had been exposed to EVD while working in West Africa (“Ebola,” 2017). Six of those patients successfully recovered and one died (“Ebola,” 2017).
Description of Ebola
Ebola is a viral disease that may present in different ways in humans. Common clinical manifestations of EVD include hemorrhagic fever, headache, severe fatigue, muscle aches, and gastrointestinal symptoms such as diarrhea and vomiting (“Ebola Virus,” n.d.). More fatal symptoms may include damage to the vasculature and hemorrhage (“Ebola Virus,” n.d.). There are five types of the Ebola virus, four of which are infectious to humans (“Ebola Virus,” n.d.). When a virus enters the body, it requires a receptor cell to act as its transportation into the host (“Ebola Virus,” n.d.). Dr. Richard Sutton in the Department of Molecular Virology and Microbiology at Baylor College of Medicine began researching past evidence that may suggest that a group of receptor cells called the Tyro3 family granted access to Ebola into the human body (“Ebola Virus,” n.d.). After analyzing the results of a reduced number of Tyro3 family receptors, Dr. Richard Sutton found that there was not a decrease of EVD infection in the experimental cells (“Ebola Virus,” n.d.). These results allowed the doctor to conclude that the Tyro3 family cells were not specific receptors to EVD (“Ebola Virus,” n.d.). According to Baylor College of Medicine, the average mortality rate for EVD is 50% but has been recorded as high as 90% in some epidemics. The morbidity rate is unknown.
Transmission of Ebola
According to Baylor College of Medicine, research shows that EVD did not initially emerge from humans, but from reservoirs of fruit bats. There are three species of fruit bats that are prominent carriers of the Ebola virus: the hammer-headed fruit bat, the little collared fruit bat and the straw-colored fruit bat (Alexander, et al., 2015). Transmission from wildlife to human populations is called pathogen spillover (Alexander, et al., 2015). Spillover is thought to occur due to the ingestion of fruit that has been contaminated with the saliva, blood or feces of infected fruit bats (Alexander, et al., 2015). Human-to-human transmission of EVD occurs when a person comes in direct contact with bodily fluids, blood of an infected person or any materials that has been contaminated with the bodily fluids or blood (“Ebola Virus,” n.d.). EVD may also be spread through contact with a person who has died from the infectious disease (“Ebola Virus,” n.d.). Ebola is very contagious; however, it is not spread through the air and is most contagious when the infected person is showing signs and symptoms of the disease (“Ebola Virus,” n.d.).
Distribution Patterns of Ebola
In 1976, the first EVD outbreak emerged in two West African countries simultaneously (“Ebola,” 2018). Since then there have been outbreaks in other countries in Europe, Asia, and North America (“Ebola,” 2018). According to the Center for Disease Control (CDC), the densest number of outbreaks has occurred in Central Africa and there is an ongoing outbreak today (“Ebola,” 2018). In 2014, the first positive case of EVD was introduced to the United States when a traveler flew from West Africa to Dallas, Texas (“Ebola,” 2017). The healthcare professionals that were caring for the traveler were exposed to the virus, but later recovered (“Ebola,” 2018). This was recorded as the first human-to-human transmission inside of the United States. Later, in 2014, 7 more people were treated for EVD in the United States and one of them died (“Ebola,” 2017). Fortunately, Oklahoma has not had any reported cases of EVD. So far, Texas and New York have been the only two states with reported EVD cases (“Ebola,” 2017).
Populations Primarily Affected by Ebola
The first population that had the highest rates of infection were younger, forest dwelling individuals in West Africa who were very likely to encounter and ingest forest fruits that had been infected with the feces or saliva of infected fruit bats (Lever & Whitty, 2016). As the number of outbreaks continued to grow, more populations were effected. Low socioeconomic status, poor healthcare systems and an enormous population expansion were all factors that contributed to climbing numbers of EVD cases in West Africa (Alexander, et al., 2015). A very large number of individuals have begun migrating to different areas of West Africa in search of better socioeconomic conditions. This migration has contributed to the regional explosion of positive EVD cases (Alexander, et al., 2015).
According to Baylor College of Medicine, there are no Food and Drug Administration (FDA) approved vaccines or drugs that are available to treat or prevent EVD. In 2016, Lever and Whitty wrote an article that stated that there were two potential vaccines that were in the Phase I trials. These vaccines, rVSV-EBOV and ChAd3-EBOV, were in Phase III trials as of 2017 (Trad, et al., 2017). According to the CDC, the FDA is expected to approve the rVSV-EBOV vaccine in 2019 (“Ebola,” 2017). The availability of these vaccines in the United States and Oklahoma are unknown. Other preventative measures may be taken to decrease the spread of EVD. These preventative measures include diligent handwashing with alcohol-based sanitizer, hot water and soap or a mild chlorine solution when water, soap or sanitizer is not available (“Ebola,” 2017). The CDC provides guidelines for healthcare workers who are caring for a patient who has a positive case of EVD. These guidelines cover an array of topics, some of which include personal protective equipment (PPE), decontamination precautions, and patient assessment precautions (“Ebola,” 2017). The World Health Organization (WHO) provides a surplus of information on their website that is very informative to a person who would like to learn more about the disease. The website provides information such as frequently asked questions, health and safety precautions, facts about Ebola and up-to-date information regarding the current outbreak in the Democratic Republic of the Congo (Ebola, 2019).
- Alexander, K. A., Sanderson, C. E., Marathe, M., Lewis, B. L., Rivers, C. M., Shaman, J., . . . Eubank, S. (2015). What Factors Might Have Led to the Emergence of Ebola in West Africa? Public Library of Science: Neglected Tropical Diseases. doi:https://doi.org/10.1371/journal.pntd.0003652
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