| Electron microscope image of the Ebola virus (source: CDC) |
The virus comes from the filoviridae family, similar to the Marburg virus. It is named after the Ebola River in Zaire, Africa, near where the first outbreak was noted by Dr. Ngoy Mushola in 1976 after a significant outbreak in Yambuku, Zaire (now the Democratic Republic of the Congo), and Nzara, in western Sudan. Of 602 identified cases, there were 397 deaths.
The two strains identified in 1976 were named Ebola-Zaire (EBO-Z) and Ebola-Sudan (EBO-S). The outbreak in Sudan showed a lower fatality rate -- 50% -- compared to the 90% mortality rate of the Zaire strain. In 1990, a second, similar virus was identified in Reston, Virginia amongst monkeys imported from the Philippines, and was named Ebola-Reston.
Further outbreaks have occurred in Zaire/Congo (1995 and 2003), Gabon (1994, 1995 and 1996), and in Uganda (2000). A new subtype was identified from a single human case in the Côte d'Ivoire in 1994, EBO-CI.
Of around 1500 identified Ebola cases, two-thirds of the patients have died. The animal (or other) reservoir which sustains the virus between outbreaks has not been identified.
Ebola-Zaire, the first-discovered Ebola virus, is also the most deadly. At its worst, it has a ninety percent fatality rate. There have been more outbreaks of Ebola-Zaire than any other type of Ebola virus (“Ebola Hemorrhagic Fever”). The first outbreak took place in 1976 in Yambuku, Zaire (now Democratic Republic of Congo). Mabelo Lokela checked into the local hospital with a fever. One of the nurses assumed Lokela had malaria and gave him a quinine shot. When Lokela returned home from the hospital and died, the women of his family conducted a traditional African funeral for him. In preparation for this funeral, they removed all the blood and excreta from his body with their bare hands. Most of the women in his family died soon afterwards (Draper 19).
Meanwhile, the nurses at the hospital had an Ebola epidemic on their hands. The needle used for Lokela’s quinine injection was inadequately sterilized, so Ebola had spread from patient to patient as the needles were reused. They called Dr. Ngoi Mushola, the area director, for help. He taught them how to sterilize their needles and purify water. He also told the nurses to instruct patients’ families not to bury their dead inside or close to their homes as tradition dictated, since Ebola could spread from dead bodies. He also called authorities in Kinshasa, the nation’s capital, for help. Kinshasa sent a microbiologist and an epidemiologist who performed autopsies on dead patients and collected samples. Soon afterwards, the entire area was quarantined, which soon brought the disease back under control. This quarantine simply meant that the area was isolated until every ill person died. Dr. Ngwete Kikhela, the Minister of Health in Kinshasa, then contacted the United States Centers for Disease Control (CDC) for help. The CDC informed the international medical community about the epidemic (Draper 15-23).
The Ebola virus
Ebola Virus History
Ebola-Zaire
| Sources:
"Ebola Hemorrhagic Fever Table Showing Known Cases and Outbreaks, in Chronological Order." Centers for Disease Control and Prevention. 18 October 2002. http://cdc.gov/ncidod/dvrd/spb/mnpages/dispages/ebotabl.htm
"Republic of Congo: Ebola Epidemic; Emergency Appeal no. 07/03; Final Report." ReliefWeb. |
Meanwhile, another outbreak was occurring in the cities of Nzara and Maridi, Sudan. The first case that occurred in Nzara involved a worker who had been exposed to the potential natural reservoir at the local cotton factory. A natural reservoir is a carrier of the virus that is immune to its effects. Although many the creatures – ranging from spiders to insects to rats and bats -- found in the factory were tested for Ebola, none of the tests came back testing positive (Draper 30-31). The natural reservoir for Ebola is still unknown today (“Fact Sheet No. 103”).
Another case was the death of a nightclub owner in Nzara who could afford to go to the fancier hospital located in Maridi. Unfortunately, the nurses there also did not properly sterilize their needles, and the hospital, like the one in Yambuku, became a breeding ground for new Ebola cases (Draper 30-31). Several epidemics of Ebola-Zaire and Ebola-Sudan have occurred since 1976.
| Source: "Ebola Hemorrhagic Fever Table Showing Known Cases and Outbreaks, in Chronological Order." Centers for Disease Control and Prevention. 18 October 2002.http://cdc.gov/ncidod/dvrd/spb/mnpages/dispages/ebotabl.htm. |
In 1989, crab-eating macaques from the Philippines brought Ebola-Reston into quarantine facilities in Reston, Virginia, Texas, and Pennsylvania. Four people developed antibodies from exposure to the virus, but none fell ill. Ebola-Reston has re-emerged in monkeys several times since then, but no humans have contracted the virus (“Ebola Hemorrhagic Fever Table”). It is unknown why the monkeys got sick, but not the humans (Draper 40).
In 1994, a scientist became ill after conducting an autopsy on a wild chimpanzee. The scientist recovered (“Ebola Hemorrhagic Fever Table”). Not much is known about this form of Ebola since only one case of it has been discovered.
Among humans, the virus is transmitted by direct contact with infected body fluids such as blood. The cause of the index case is unknown.
The incubation period of Ebola haemorrhagic fever varies from two days to four weeks. Symptoms are variable too, but the onset is usually sudden and characterised by high fever, prostration, myalgia, arthralgia, abdominal pains and headache. These symptoms progress to vomiting, diarrhea, oropharyngeal lesions, conjunctivitis, organ damage (notably the kidney and liver) by co-localized necrosis, proteinuria, and bleeding both internal and external, commonly through the gastrointestinal tract. Death or recovery to convalescence occurs within six to ten days.
No specific treatment has been proven effective, and no vaccine currently exists. A vaccine is in the developmental stages. Ebola is known to exist in humans and a few monkey species can be infected. To develop the vaccine, monkeys are used but it can not be tested on humans except in outbreak environments so the vaccine must be tested extensively and meet strict government regulations. Also, in the development of a vaccine, accessibility and cost for people of poor nations and the transportation efficiency of it must be considered.
Although there is no specific treatment for patients with Ebola, there have been entire books written about how to prevent it from spreading from the patient to health care workers or other patients. The first step in prevention is to make advanced preparations for Ebola and other viral hemorrhagic fevers (VHFs). Selecting a VHF Coordinator to oversee preparations for VHF activities, such as the following, does this:
The next thing to do is isolate the patient from other patients who may get sick and health care workers who are not directly involved with the patient's care. The patient should be given intravenous support, as he or she is probably dehydrated from losing fluids through vomiting and diarrhea. Finally, if the patient expires, the body should be properly disposed of, preferably through cremation, so that the dead body will not spread disease to other people (CDC 26).
Ebola has sharply affected tourism in the countries where it is present, especially in the Democratic Republic of the Congo (“TED Case Study”). Other countries that have been hard hit include Uganda, where an outbreak in 2000 stifled its waning tourism industry (Busharizi). Ebola has also made countries like Uganda, Democratic Republic of the Congo, and Sudan to lose revenue through the loss of people who would have been able to work and benefit their nation's economy. For example, many health workers' lives have been lost because they became sick in hospitals due to inadequate sanitation procedures. It is unknown how much money exactly was lost through these deaths (Busharizi).
Another loss in economic revenue has been the deaths of monkeys traded throughout the world for experimental purposes. Three out of the four Japanese airlines that transport monkeys throughout the world have quit transporting monkeys because of the risk of Ebola. Not so long ago, a monkey cost $1500 to transport, but now costs three times as much, partly because of the monkey ban (“TED Case Study”).
Since Ebola is so unpredictable, it is impossible to detect very many trends that it causes. Ebola first appeared out of nowhere in 1976 and disappeared until 1989 (Draper 6). It is possible to say that since this disease can be transmitted from monkeys to humans, that Ebola will probably reappear in places where there are significant monkey populations in Asia and Africa.
It is not known at this time whether there are individual trends in the Ebola virus, either. As of this date, there is no information about a person who has caught Ebola twice and lived to tell about it, so it is impossible to say whether a person is immune to it after they survive a first episode.
Conspiracy theorists insist that Ebola is a manmade virus created by scientists in order to create biological weapons. Contaminated hepatitis, polio, and smallpox vaccines then spread the diseases, perhaps intentionally, in order to quell threats posed by “communism, black nationalism, and the Third World populations” (Horowitz, dustjacket). Actually, the book he has written contains at least one grave error: It calls the Marburg virus a form of Ebola (Horowitz 395), even though Ebola and Marburg are not even the same species. Ebola and Marburg are close cousins, but the Marburg virus is not a form of Ebola (“Filoviruses”). How Horowitz made such a grave mistake throws a harsh light on his entire argument, and it encourages one to throw out the entire book because of that one error.
Bioterrorism, or use of the Ebola virus as a biological weapon, is a common fear of people who know about the virus. There is not much information published about the bioterrorism potential of Ebola, obviously for security reasons. However, scientists do say that altering the Ebola virus for biological warfare is possible although unlikely. The difficulty in changing Ebola to a potential virus is twofold: first, the Ebola virus would have to be airborne to be effective. Although some have noted that Ebola can travel through water droplets in the air (Preston 260), it is currently not possible for Ebola to travel through the air by itself (Russell). Second, the Ebola virus would have to be transported in a way that is not fatal to the people who use it as a weapon, or would have to be carried by people who are willing to die a gruesome death. It is unknown how many people would be willing to do this.
See also:
“Breakthrough in Ebola Vaccine.” BBC News World Edition 6 August 2003. 3 September 2003 " class="external">http://news.bbc.co.uk/go/pr/fr/-/2/hi/health/3126365.stm.
Busharizi, Paul. “Ebola Hits Uganda’s Tourism Revival Effort.” Planet Ark. 27 December 2000. 3 November 2003 " class="external">http://www.planetark.org/dailynewsstory.cfm?newsid=0385.
Centers for Disease Control and Prevention and World Health Organization. Infection for Health Control of Viral Hemorrhagic Fevers in the African Health Care Setting. Atlanta, Center for Disease Control and Prevention, 1998. 3 September 2003 " class="external">http://www.cdc.gov/ncidod/dvrd/spb/mnpages/vhfmanual/entire.pdf.
Draper, Allison Stark. Ebola. New York: The Rosen Publishing Group, Inc., 2002.
“Ebola.” Wikipedia. 14 August 2003. 8 September 2003 " class="external">http://en.wikipedia.org/wiki/Ebola.
“Ebola Hemorrhagic Fever.” Centers for Disease Control Special Pathogens Branch. 8 September 2003 " class="external">http://www.cdc.gov/ncidod/dvrd/spb/mnpages/dispages/ebola.htm.
"Ebola Hemorrhagic Fever Table Showing Known Cases and Outbreaks, in Chronological Order." Centers for Disease Control and Prevention. 18 October 2002. 3 September 2003 " class="external">http://cdc.gov/ncidod/dvrd/spb/mnpages/dispages/ebotabl.htm.
“Fact Sheet Number 103 Ebola Hemorrhagic Fever.” World Health Organization. December 2000. 3 September 2003 " class="external">http://www.who.int/inf-fs/en/fact103.html.
“Filoviruses.” Centers for Disease Control Special Pathogens Branch. 3 September 2003 http://www.cdc.gov/ncidod/dvrd/spb/mnpages/dispages/ filoviruses.htm.
Horowitz, Leonard G. Emerging Viruses: AIDS & Ebola -- Nature, Accident, or Intentional?. Rockport, MA: Tetrahedron, Inc., 1996.
Preston, Richard. The Hot Zone. New York: Anchor Books Doubleday, 1994.
Russell, Brett. “What are the Chances?” Ebola FAQ. 3 November 2003 " class="external">http://www.brettrussell.com/personal/what_are_the_chances_.html.
“TED Case Study: Ebola and Trade.” Trade and Environment Databases. May 1997. 7 November 2003 " class="external">http://www.american.edu/projects/mandala/TED/ebola.htm.
Ebola-Reston
Ebola-Ivory Coast
Ebola haemorrhagic fever
Treatment
Prevention
The next step is maintaining a minimum standard of cleanliness in the hospital. This includes washing hands and sterilizing needles (CDC 9-18). Also, the medical staff must be informed about the different types of VHFs, including Ebola, and their symptoms. Symptoms that are common to many VHFs are severe weakness and fatigue, and a fever for more than 72 hours and less than three weeks. The patient also may have unexplained bleeding from the mucous membranes, skin, eyes, or gastrointestinal tract. The patient may also be going into shock (has a blood pressure of less than 90 mm Hg or a rapid weak pulse.) Finally, that patient may have had contact with someone in the last three weeks that had an unexplained illness with fever or bleeding or who died with an unexplained severe illness with a fever (CDC 23).Economic Impact
Trends
Conspiracy Theories
Bioterrorism
External links
Works Cited