Ebola causes: Difference between revisions
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==Overview== | ==Overview== | ||
Ebola hemorrhagic fever (Ebola fever) is caused by a virus belonging to the family called [[Filoviridae]]. Three have been reported to cause [[disease]] in humans: Ebola-Zaire virus, Ebola-Sudan virus, and Ebola-Ivory Coast virus. The human disease has so far been limited to parts of Africa. A very small number of people in the United States who were infected with the fourth type of the virus, known as Ebola Reston, did not develop any signs of disease. | |||
==Causes== | |||
Ebola hemorrhagic fever (Ebola fever) is caused by a virus belonging to the family called [[Filoviridae]]. Scientists have identified four types of the Ebola virus. Three have been reported to cause [[disease]] in humans: Ebola-Zaire virus, Ebola-Sudan virus, and Ebola-Ivory Coast virus. The human disease has so far been limited to parts of Africa. | Ebola hemorrhagic fever (Ebola fever) is caused by a virus belonging to the family called [[Filoviridae]]. Scientists have identified four types of the Ebola virus. Three have been reported to cause [[disease]] in humans: Ebola-Zaire virus, Ebola-Sudan virus, and Ebola-Ivory Coast virus. The human disease has so far been limited to parts of Africa. | ||
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The disease can be passed to humans from infected animals and animal materials. Ebola can also be spread between humans by close contact with infected bodily fluids or through infected [[needles]] in the hospital. | The disease can be passed to humans from infected animals and animal materials. Ebola can also be spread between humans by close contact with infected bodily fluids or through infected [[needles]] in the hospital. | ||
=== | ===Subtypes=== | ||
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Microbiologists have defined several subtypes of Ebola. The following list is not exclusive. A new strain of Ebola has been identified in Uganda during an outbreak. It does not match any of the four Ebola subtypes previously identified by scientists.<ref>{{cite news |first= |last= |authorlink= |coauthors= |title=New subtype of Ebola suspected in Uganda |url=http://www.usatoday.com/news/world/2007-11-30-uganda-ebola_N.htm |work=[[USA Today]] |publisher= |date=2007-11-30 |accessdate=2008-02-25 }}</ref> | |||
=== ''Zaïre ebola virus'' === | |||
[[Image:Ebola-zaire chart.jpg|thumb|300px|right|Known human cases and deaths during outbreaks of ''Zaïre Ebolavirus'' between 1976 and 2003]] | |||
The ''Zaïre Ebola virus'' has the highest mortality rate, up to 90% in some epidemics, with an average of approximately 83% mortality over 27 years. The case-fatality rates were 88% in 1976, 100% in 1977, 59% in 1994, 81% in 1995, 73% in 1996, 80% in 2001-2002 and 90% in 2003. There have been more outbreaks of ''Zaïre Ebola virus'' than any other strain. | |||
The first outbreak took place on [[August 26]] [[1976]] in [[Yambuku]], a town in the north of [[Zaire|Zaïre]]. The first recorded case was Mabalo Lokela, a 44-year-old schoolteacher returning from a trip around the north of the state. His high fever was diagnosed as possible [[malaria]] and he was subsequently given a [[quinine]] shot. Lokela returned to the hospital every day. A week later, his symptoms included uncontrolled [[vomiting]], bloody diarrhea, [[headache]], [[dizziness]], and trouble breathing. Later, he began bleeding from his nose, mouth, and anus. Lokela died on [[September 8]] [[1976]], roughly 14 days after the onset of symptoms. | |||
Soon after, more patients arrived with varying but similar symptoms including fever, headache, muscle and joint aches, fatigue, nausea, and dizziness. These often progressed to bloody diarrhea, severe vomiting, and bleeding from the nose, mouth, and anus. The initial transmission was believed to be due to reuse of the needle for Lokela’s injection without sterilization. Subsequent transmission was also due to care of the sick patients without [[Universal precautions|barrier nursing]] and the traditional burial preparation method, which involved washing and [[gastrointestinal tract]] cleansing. | |||
Two nuns working in Yambuku as nurses also died in the same outbreak.<ref>{{cite paper |last=Isaacson |first=Margaretha |author= |authorlink= |coauthors=''et al.'' |title=Two Belgian nurses died of Ebola |version= |publisher= |date= |url=http://www.itg.be/ebola/ebola-12.htm |format= |id= |accessdate= }}</ref> | |||
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=== ''Sudan ebolavirus'' === | |||
[[Image:Ebola-sudan chart.jpg|thumb|300px|right|Known human cases and deaths during outbreaks of Sudan Ebolavirus between 1976 and 2003]] | |||
Sudan Ebolavirus was the second strand of Ebola reported in 1976. It apparently originated amongst cotton factory workers in Nzara, Sudan. The first case reported was a worker exposed to a potential natural reservoir at the cotton factory. Scientists tested all animals and insects in response to this, however none tested positive for the virus. The carrier is still unknown. | |||
A second case involved a nightclub owner in Nzara, [[Sudan]]. The local hospital, Maridi, tested and attempted to treat the patient; however, nothing was successful, and he died. The hospital did not advocate safe and practical procedures in sterilizing and disinfecting the medical tools used on the nightclub owner, likely facilitating the spread of the virus in the hospital. | |||
The most recent outbreak of ''Sudan Ebolavirus'' occurred in [[May]] [[2004]]. As of [[May]] [[2004]], 20 cases of ''Sudan Ebolavirus'' were reported in [[Yambio|Yambio County]], [[Sudan]], with 5 deaths resulting. The [[Centers for Disease Control and Prevention]] confirmed the virus a few days later. The neighbouring countries of [[Uganda]] and the [[Democratic Republic of Congo]] have increased surveillance in bordering areas, and other similar measures have been taken to control the outbreak. The average fatality rates for ''Sudan Ebolavirus'' were 54% in 1976, 68% in 1979, and 53% in 2000/2001. The average case-fatality rate is 54%. | |||
<!-- The correct term is "ebolavirus" without any spaces --> | |||
===''Reston ebolavirus''=== | |||
{{main|Ebola Reston}} | |||
First discovered in [[November]] [[1989]] in a group of 100 [[Crab-eating Macaque|Crab-eating macaques]] (''{{lang|la|Macaca fascicularis}}'') imported from the [[Philippines]] to [[Reston, Virginia|Reston]], [[Virginia]]. A parallel infected shipment was also sent to [[Philadelphia]]. This strain was highly lethal in monkeys, but did not cause any fatalities in humans. Six of the Reston primate handlers tested positive for the virus, two due to previous exposure. The bio-thriller ''[[The Hot Zone]]'' was based on this incident. | |||
Further ''Reston Ebolavirus'' infected monkeys were shipped again to Reston, and [[Alice, Texas|Alice]], [[Texas]], in February of 1990. More ''Reston Ebolavirus'' infected monkeys were discovered in 1992 in [[Siena]], [[Italy]] and in Texas again in March 1996. A high rate of co-infection with [[Simian hemorrhagic fever virus|Simian hemorragic fever]] (SHF) was present in all infected monkeys. No human illness has resulted from these two outbreaks. | |||
===''Tai (Ivory Coast) ebolavirus''=== | |||
This subtype of Ebola was first discovered amongst [[chimpanzee]]s of the Tai Forest in [[Côte d'Ivoire|Côte d’Ivoire]], [[Africa]]. On [[November 1]] [[1994]], the corpses of two chimpanzees were found in the forest. [[Necropsy|Necropsies]] showed blood within the heart to be liquid and brown, no obvious marks seen on the organs, and one presented lungs filled with liquid blood. Studies of tissues taken from the chimps showed results similar to human cases during the 1976 Ebola outbreaks in Zaïre and Sudan. Later in 1994, more dead chimpanzees were discovered, with many testing positive to Ebola using molecular techniques. The source of contamination was believed to be the meat of infected [[Western Red Colobus]] monkeys, upon which the chimpanzees preyed.<ref>[http://virus.stanford.edu/filo/eboci.html Ebola Cote d'Ivoire Outbreaks<!-- Bot generated title -->]</ref> | |||
One of the scientists performing the necropsies on the infected chimpanzees contracted Ebola. She developed symptoms similar to [[dengue fever]] approximately a week after the necropsy and was transported to Switzerland for treatment. After two weeks she was discharged from hospital, and was fully recovered six weeks after the infection. | |||
===''Bundibugyo ebolavirus''=== | |||
On [[November 24]] [[2007]], the Uganda Ministry of Health confirmed an outbreak of Ebola in the [[Bundibugyo District]]. After confirmation of samples tested by the United States National Reference Laboratories and the [[Centers for Disease Control]], the World Health Organization has confirmed the presence of a new species of the Ebola virus. On [[February 20]] [[2008]], the Uganda Ministry officially announced the end of the epidemic in Bundibugyo with the last infected person discharged on [[January 8]] [[2008]].<ref>{{cite press release |title=End of Ebola outbreak in Uganda |publisher=[[World Health Organization]] |date=2008-02-20 |url=http://www.who.int/csr/don/2007_02_20b/en/index.html |format= |language= |accessdate= |quote= }}</ref> Ugandan officials confirmed a total of 149 cases of this new Ebola species, with 37 deaths attributed to the strain.<ref>{{cite news |first=Tim |last= Cocks|authorlink= |coauthors= |title=Uganda confirms 113 suspected Ebola cases |url=http://africa.reuters.com/top/news/usnBAN126612.html |work= |publisher=[[Reuters]] |date=2007-12-11 |accessdate=2008-02-25 }}</ref> | |||
==References== | |||
{{Reflist|2}} | |||
[[Category:Ebola| ]] | |||
[[Category:Mononegavirales]] | |||
[[Category:Viral diseases]] | |||
[[Category:Biological weapons]] | |||
[[Category:Zoonoses]] | |||
[[Category:Hemorrhagic fevers]] | |||
[[Category:Mature chapter]] | |||
[[Category:Overview complete]] | |||
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Revision as of 21:31, 7 December 2012
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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]
Overview
Ebola hemorrhagic fever (Ebola fever) is caused by a virus belonging to the family called Filoviridae. Three have been reported to cause disease in humans: Ebola-Zaire virus, Ebola-Sudan virus, and Ebola-Ivory Coast virus. The human disease has so far been limited to parts of Africa. A very small number of people in the United States who were infected with the fourth type of the virus, known as Ebola Reston, did not develop any signs of disease.
Causes
Ebola hemorrhagic fever (Ebola fever) is caused by a virus belonging to the family called Filoviridae. Scientists have identified four types of the Ebola virus. Three have been reported to cause disease in humans: Ebola-Zaire virus, Ebola-Sudan virus, and Ebola-Ivory Coast virus. The human disease has so far been limited to parts of Africa.
A very small number of people in the United States who were infected with the fourth type of the virus, known as Ebola Reston, did not develop any signs of disease.
The disease can be passed to humans from infected animals and animal materials. Ebola can also be spread between humans by close contact with infected bodily fluids or through infected needles in the hospital.
Subtypes
Microbiologists have defined several subtypes of Ebola. The following list is not exclusive. A new strain of Ebola has been identified in Uganda during an outbreak. It does not match any of the four Ebola subtypes previously identified by scientists.[1]
Zaïre ebola virus
The Zaïre Ebola virus has the highest mortality rate, up to 90% in some epidemics, with an average of approximately 83% mortality over 27 years. The case-fatality rates were 88% in 1976, 100% in 1977, 59% in 1994, 81% in 1995, 73% in 1996, 80% in 2001-2002 and 90% in 2003. There have been more outbreaks of Zaïre Ebola virus than any other strain. The first outbreak took place on August 26 1976 in Yambuku, a town in the north of Zaïre. The first recorded case was Mabalo Lokela, a 44-year-old schoolteacher returning from a trip around the north of the state. His high fever was diagnosed as possible malaria and he was subsequently given a quinine shot. Lokela returned to the hospital every day. A week later, his symptoms included uncontrolled vomiting, bloody diarrhea, headache, dizziness, and trouble breathing. Later, he began bleeding from his nose, mouth, and anus. Lokela died on September 8 1976, roughly 14 days after the onset of symptoms. Soon after, more patients arrived with varying but similar symptoms including fever, headache, muscle and joint aches, fatigue, nausea, and dizziness. These often progressed to bloody diarrhea, severe vomiting, and bleeding from the nose, mouth, and anus. The initial transmission was believed to be due to reuse of the needle for Lokela’s injection without sterilization. Subsequent transmission was also due to care of the sick patients without barrier nursing and the traditional burial preparation method, which involved washing and gastrointestinal tract cleansing. Two nuns working in Yambuku as nurses also died in the same outbreak.[2]
Sudan ebolavirus
Sudan Ebolavirus was the second strand of Ebola reported in 1976. It apparently originated amongst cotton factory workers in Nzara, Sudan. The first case reported was a worker exposed to a potential natural reservoir at the cotton factory. Scientists tested all animals and insects in response to this, however none tested positive for the virus. The carrier is still unknown. A second case involved a nightclub owner in Nzara, Sudan. The local hospital, Maridi, tested and attempted to treat the patient; however, nothing was successful, and he died. The hospital did not advocate safe and practical procedures in sterilizing and disinfecting the medical tools used on the nightclub owner, likely facilitating the spread of the virus in the hospital. The most recent outbreak of Sudan Ebolavirus occurred in May 2004. As of May 2004, 20 cases of Sudan Ebolavirus were reported in Yambio County, Sudan, with 5 deaths resulting. The Centers for Disease Control and Prevention confirmed the virus a few days later. The neighbouring countries of Uganda and the Democratic Republic of Congo have increased surveillance in bordering areas, and other similar measures have been taken to control the outbreak. The average fatality rates for Sudan Ebolavirus were 54% in 1976, 68% in 1979, and 53% in 2000/2001. The average case-fatality rate is 54%.
Reston ebolavirus
First discovered in November 1989 in a group of 100 Crab-eating macaques (Macaca fascicularis) imported from the Philippines to Reston, Virginia. A parallel infected shipment was also sent to Philadelphia. This strain was highly lethal in monkeys, but did not cause any fatalities in humans. Six of the Reston primate handlers tested positive for the virus, two due to previous exposure. The bio-thriller The Hot Zone was based on this incident. Further Reston Ebolavirus infected monkeys were shipped again to Reston, and Alice, Texas, in February of 1990. More Reston Ebolavirus infected monkeys were discovered in 1992 in Siena, Italy and in Texas again in March 1996. A high rate of co-infection with Simian hemorragic fever (SHF) was present in all infected monkeys. No human illness has resulted from these two outbreaks.
Tai (Ivory Coast) ebolavirus
This subtype of Ebola was first discovered amongst chimpanzees of the Tai Forest in Côte d’Ivoire, Africa. On November 1 1994, the corpses of two chimpanzees were found in the forest. Necropsies showed blood within the heart to be liquid and brown, no obvious marks seen on the organs, and one presented lungs filled with liquid blood. Studies of tissues taken from the chimps showed results similar to human cases during the 1976 Ebola outbreaks in Zaïre and Sudan. Later in 1994, more dead chimpanzees were discovered, with many testing positive to Ebola using molecular techniques. The source of contamination was believed to be the meat of infected Western Red Colobus monkeys, upon which the chimpanzees preyed.[3] One of the scientists performing the necropsies on the infected chimpanzees contracted Ebola. She developed symptoms similar to dengue fever approximately a week after the necropsy and was transported to Switzerland for treatment. After two weeks she was discharged from hospital, and was fully recovered six weeks after the infection.
Bundibugyo ebolavirus
On November 24 2007, the Uganda Ministry of Health confirmed an outbreak of Ebola in the Bundibugyo District. After confirmation of samples tested by the United States National Reference Laboratories and the Centers for Disease Control, the World Health Organization has confirmed the presence of a new species of the Ebola virus. On February 20 2008, the Uganda Ministry officially announced the end of the epidemic in Bundibugyo with the last infected person discharged on January 8 2008.[4] Ugandan officials confirmed a total of 149 cases of this new Ebola species, with 37 deaths attributed to the strain.[5]
References
- ↑ "New subtype of Ebola suspected in Uganda". USA Today. 2007-11-30. Retrieved 2008-02-25.
- ↑ Template:Cite paper
- ↑ Ebola Cote d'Ivoire Outbreaks
- ↑ "End of Ebola outbreak in Uganda" (Press release). World Health Organization. 2008-02-20.
- ↑ Cocks, Tim (2007-12-11). "Uganda confirms 113 suspected Ebola cases". Reuters. Retrieved 2008-02-25.