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==Overview==
==Overview==
'''Ebola''' is the common term for a group of [[virus]]es belonging to genus ''[[Ebola]]'', family ''[[Filoviridae]]'', and for the disease which they cause, ''Ebola [[viral haemorrhagic fever|hemorrhagic fever]]''. The viruses are characterised by a long, filamentous morphology surrounded by a protein/lipid [[viral envelope]]. Ebola viruses are morphologically similar to the [[Marburg virus]], also in the family ''Filoviridae'', and share similar disease symptoms. Ebola has caused a number of serious and highly publicized outbreaks since its discovery.<ref name="CDCEbola">{{cite web | url = http://www.cdc.gov/ncidod/dvrd/spb/mnpages/dispages/ebotabl.htm | title = Ebola Cases and Outbreaks - CDC Special Pathogens Branch | accessdate = 2007-12-08 | author = | authorlink = | coauthors = | date = | format = | work = | publisher = Centers for Disease Control and Prevention}}</ref>
Ebola virus disease (EVD) is one of numerous viral hemorrhagic fevers (VHF). It is a severe, often fatal disease in human and nonhuman primates. Ebola virus is spread by direct contact with the blood or body fluids (such as urine, saliva, feces, vomit and semen) of an infected person or by being exposed to objects that have been contaminated with infected blood or body fluids. The incubation period is usually 8–10 days (rarely ranging from 2 to 21 days). Patients can transmit the virus once symptoms appear and through the later stages of disease, as well as postmortem. Ebola has caused a number of serious and highly publicized outbreaks since its discovery.<ref name="CDCEbola">{{cite web | url = http://www.cdc.gov/ncidod/dvrd/spb/mnpages/dispages/ebotabl.htm | title = Ebola Cases and Outbreaks - CDC Special Pathogens Branch | accessdate = 2007-12-08 | author = | authorlink = | coauthors = | date = | format = | work = | publisher = Centers for Disease Control and Prevention}}</ref>
 
==Historical Perspective==
==Historical Perspective==
The Ebola virus was named after the Ebola River Valley in the Democratic Republic of the Congo (formerly Zaïre), near the site of a 1976 [[outbreak]] at a mission run by Flemish nuns.<ref>{{cite journal |last=Bardi |first=Jason Socrates |authorlink= |coauthors= |year=2002 |month=|title=Death Called a River |journal=Scribbs Research Institute |volume=2 |issue=1 |pages= |id= |url=http://www.scripps.edu/newsandviews/e_20020114/ebola1.html|accessdate=2006-12-08 |quote= }}</ref> Since the initial discovery of the [[virus]], five subtypes have subsequently been identified.
The Ebola virus was named after the Ebola River Valley in the Democratic Republic of the Congo (formerly Zaïre), near the site of a 1976 [[outbreak]] at a mission run by Flemish nuns.<ref>{{cite journal |last=Bardi |first=Jason Socrates |authorlink= |coauthors= |year=2002 |month=|title=Death Called a River |journal=Scribbs Research Institute |volume=2 |issue=1 |pages= |id= |url=http://www.scripps.edu/newsandviews/e_20020114/ebola1.html|accessdate=2006-12-08 |quote= }}</ref> Since the initial discovery of the [[virus]], five subtypes have subsequently been identified.
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==Pathophysiology==
==Pathophysiology==
The Ebola virus infects the [[mononuclear]] phagocyte system, but also other [[cells]] such as [[hepatocytes]], [[spongiocytes]], [[fibroblasts]] and [[endothelial]] cells, inducing tissue [[necrosis]] and disrupting the [[hematological]] and [[coagulation]] systems. The Ebola virus is transmitted by direct contact with infected patients or animals. The natural reservoir has not been identified.<ref name="pmid8678836">{{cite journal| author=Ryabchikova E, Kolesnikova L, Smolina M, Tkachev V, Pereboeva L, Baranova S et al.| title=Ebola virus infection in guinea pigs: presumable role of granulomatous inflammation in pathogenesis. | journal=Arch Virol | year= 1996 | volume= 141 | issue= 5 | pages= 909-21 | pmid=8678836 | doi= | pmc= | url=http://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=8678836  }} </ref><ref name="pmid9728532">{{cite journal| author=Bray M, Davis K, Geisbert T, Schmaljohn C, Huggins J| title=A mouse model for evaluation of prophylaxis and therapy of Ebola hemorrhagic fever. | journal=J Infect Dis | year= 1998 | volume= 178 | issue= 3 | pages= 651-61 | pmid=9728532 | doi= | pmc= | url=http://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=9728532  }} </ref><ref name="pmid9988186">{{cite journal| author=Connolly BM, Steele KE, Davis KJ, Geisbert TW, Kell WM, Jaax NK et al.| title=Pathogenesis of experimental Ebola virus infection in guinea pigs. | journal=J Infect Dis | year= 1999 | volume= 179 Suppl 1 | issue=  | pages= S203-17 | pmid=9988186 | doi=10.1086/514305 | pmc= | url=http://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=9988186  }} </ref><ref name="pmid11798241">{{cite journal| author=Bray M, Hatfill S, Hensley L, Huggins JW| title=Haematological, biochemical and coagulation changes in mice, guinea-pigs and monkeys infected with a mouse-adapted variant of Ebola Zaire virus. | journal=J Comp Pathol | year= 2001 | volume= 125 | issue= 4 | pages= 243-53 | pmid=11798241 | doi=10.1053/jcpa.2001.0503 | pmc= | url=http://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=11798241  }} </ref>
The Ebola virus infects the [[mononuclear]] phagocyte system, but also other [[cells]] such as [[hepatocytes]], [[spongiocytes]], [[fibroblasts]] and [[endothelial]] cells, inducing tissue [[necrosis]] and disrupting the [[hematological]] and [[coagulation]] systems. The Ebola virus is transmitted by direct contact with [[infected]] patients or animals. The [[natural reservoir]] has not been identified.<ref name="pmid8678836">{{cite journal| author=Ryabchikova E, Kolesnikova L, Smolina M, Tkachev V, Pereboeva L, Baranova S et al.| title=Ebola virus infection in guinea pigs: presumable role of granulomatous inflammation in pathogenesis. | journal=Arch Virol | year= 1996 | volume= 141 | issue= 5 | pages= 909-21 | pmid=8678836 | doi= | pmc= | url=http://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=8678836  }} </ref><ref name="pmid9728532">{{cite journal| author=Bray M, Davis K, Geisbert T, Schmaljohn C, Huggins J| title=A mouse model for evaluation of prophylaxis and therapy of Ebola hemorrhagic fever. | journal=J Infect Dis | year= 1998 | volume= 178 | issue= 3 | pages= 651-61 | pmid=9728532 | doi= | pmc= | url=http://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=9728532  }} </ref><ref name="pmid9988186">{{cite journal| author=Connolly BM, Steele KE, Davis KJ, Geisbert TW, Kell WM, Jaax NK et al.| title=Pathogenesis of experimental Ebola virus infection in guinea pigs. | journal=J Infect Dis | year= 1999 | volume= 179 Suppl 1 | issue=  | pages= S203-17 | pmid=9988186 | doi=10.1086/514305 | pmc= | url=http://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=9988186  }} </ref><ref name="pmid11798241">{{cite journal| author=Bray M, Hatfill S, Hensley L, Huggins JW| title=Haematological, biochemical and coagulation changes in mice, guinea-pigs and monkeys infected with a mouse-adapted variant of Ebola Zaire virus. | journal=J Comp Pathol | year= 2001 | volume= 125 | issue= 4 | pages= 243-53 | pmid=11798241 | doi=10.1053/jcpa.2001.0503 | pmc= | url=http://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=11798241  }} </ref>


==Causes==
==Causes==
Ebola hemorrhagic fever (Ebola fever) is caused by a [[virus]] belonging to the family called [[Filoviridae]]. Three types of virus 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.
Ebola infection is caused by a [[virus]] that belongs to the family [[Filoviridae]]. Three [[viral]] subtypes 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.


==Differentiating Ebola from other Diseases==
==Differentiating Ebola from other Diseases==
There are other conditions, such as [[Marburg virus]], [[Lassa fever]], [[Typhoid fever]]  and [[Malaria]] that involve hemorrhage and/or high fever as part of their presentation, and therefore resemble Ebola virus disease. The [[clinician]] must treat the most likely cause of the fever according to local epidemiology and the appropriate treatment guidelines. If the [[fever]] continues after 3 days of recommended treatment, and if the patient has [[signs]] such as [[bleeding]] or [[shock]], the [[clinician]] must consider a viral hemorrhagic fever (VHF). It is important to review the patient’s history for any contact with someone who was ill with [[fever]] and [[bleeding]] or who died from an unexplained [[illness]] with [[fever]] and [[bleeding]]. If no other cause is found for the patient’s [[signs]] and [[symptoms]], the [[clinician]] must suspect a VHF.<ref name=CDC>{{cite web | title = Infection Control for Viral Haemorrhagic Fevers in the African Health Care Setting  | url = http://www.who.int/csr/resources/publications/ebola/whoemcesr982sec1-4.pdf }}</ref>
Ebola must be differentiated from other diseases that cause hemorrhage and/or high [[fever]] as part of their presentation such as [[Marburg virus]], [[Lassa fever]], [[Typhoid fever]]  and [[Malaria]]. The [[clinician]] must first rule out other more common causes of the [[fever]] before considering a [[viral hemorrhagic fever]] ([[VHF]]) such as Ebola, and the consideration of a [[VHF]] should be based upon epidemiology and demographics as well as sign and symptoms.<ref>{{cite web | title = WHO Infection Control for Viral Haemorrhagic Fevers in the African Health Care Setting  | url = http://www.who.int/csr/resources/publications/ebola/whoemcesr982sec1-4.pdf }}</ref> A [[VHF]] such as Ebola, should be suspected in [[febrile]] persons who, within 3 weeks before onset of [[fever]], have either: 1) traveled in the specific local area of a country where [[VHF]] has recently occurred; 2) had direct unprotected contact with blood, other body fluids, secretions, or excretions of a person or animal with VHF; 3) if the patient had any contact with someone who was ill with [[fever]] and [[bleeding]] or who died from an unexplained [[illness]] with [[fever]] and [[bleeding]]; 4) had a possible exposure when working in a laboratory that handles [[hemorrhagic fever]] viruses; 5) If a [[fever]] continues after 3 days of empiric treatment, and if the patient has [[signs]] such as [[bleeding]] or [[shock]], the [[clinician]] must consider a [[VHF]]; 6) if no other cause is found for the patient’s [[signs]] and [[symptoms]], the [[clinician]] must suspect a [[VHF]].


==Epidemiology and Demographics==
==Epidemiology and Demographics==
Outbreaks of EVD have mainly been restricted to Africa. The virus often consumes the population. Governments and individuals quickly respond to quarantine the area while the lack of roads and transportation helps to contain the outbreak. The potential for widespread EVD [[epidemics]] is considered low due to the high case-fatality rate, the rapidity of demise of patients, and the often remote areas where [[infections]] occur.
[[Outbreaks]] of Ebola have been generally restricted to Africa. Governments and individuals should quickly [[quarantine]] the area. Lack of roads and transportation help to contain the [[outbreak]] in remote areas. The potential for widespread Ebola virus disease [[epidemics]] is considered low due to the high case-fatality rate, the rapidity of demise of patients, and the often remote areas where [[infections]] occur.


==Risk Factors==
==Risk Factors==
The main [[risk factors]] for Ebola virus disease are traveling to [[endemic]] areas, to be a health professional taking care of infected [[patients]] and researchers working with animal models of the Ebola virus disease.<ref name=CDC>{{cite web | title = Ebola Hemorrhagic Fever Information Packet  | url = http://www.cdc.gov/ncidod/dvrd/spb/mnpages/dispages/Fact_Sheets/Ebola_Fact_Booklet.pdf }}</ref>
The main [[risk factors]] for Ebola virus disease are traveling to [[endemic]] areas, to be a health professional taking care of infected [[patients]] and researchers working with animal models of the Ebola virus disease.<ref name=CDC>{{cite web | title = CDC Ebola Hemorrhagic Fever Information Packet  | url = http://www.cdc.gov/ncidod/dvrd/spb/mnpages/dispages/Fact_Sheets/Ebola_Fact_Booklet.pdf | year = April 2010 }}</ref>


==Natural History==
==Natural History==
Ebola virus disease without supportive care, progresses to eventually cause death. Ebola virus disease can be complicated by the development of [[multiorgan failure]] and [[shock]]. The [[prognosis]] of Ebola virus disease is poor, and depends of the supportive care given and the Ebola virus strain. The Zaire Ebola virus has mortality rate as high as 90%.<ref name=CDC>{{cite web | title = Ebola Hemorrhagic Fever Information Packet  | url = http://www.cdc.gov/ncidod/dvrd/spb/mnpages/dispages/Fact_Sheets/Ebola_Fact_Booklet.pdf }}</ref>
Ebola infection rapidly progresses to death in the absence of supportive care. Ebola infection can be complicated by [[multiorgan failure]] and [[shock]]. The [[prognosis]] of Ebola infection is poor, and depends upon the Ebola virus strain. The Zaire Ebola virus has mortality rate as high as 90%.<ref name=CDC>{{cite web | title = CDC Ebola Hemorrhagic Fever Information Packet  | url = http://www.cdc.gov/ncidod/dvrd/spb/mnpages/dispages/Fact_Sheets/Ebola_Fact_Booklet.pdf | year = April 2010 }}</ref>


==Diagnosis==
==Diagnosis==
===History and Symptoms===
===History and Symptoms===
Despite the existence of different [[species]] of ''Ebola virus'', a common [[syndrome|clinical syndrome]] has been described among these different [[filovirus|filoviroses]], with the difference residing essentially in the severity of the presentation and respective [[mortality rate]].  Ebola hemorrhagic fever is potentially lethal and encompasses a range of symptoms including [[fever]], [[chills]] [[vomiting]], [[diarrhea]], generalized [[pain]] or [[malaise]], and sometimes [[internal bleeding|internal]] and [[hemorrhage|external bleeding]], that follow an incubation period of 2-21 days.
Ebola causes a variety of [[symptoms]] which may include [[fever]], [[chills]] [[vomiting]], [[diarrhea]], generalized [[pain]] or [[malaise]], and sometimes [[internal bleeding|internal]] and [[hemorrhage|external bleeding]], that follow an [[incubation period]] of 2-21 days.  These [[symptoms]] are common to all [[species]] of ''[[Ebola virus]]'', but the different [[species]] may present with differences in the severity of [[symptoms]].


===Physical Examination===
===Physical Examination===
''Ebola hemorrhagic fever'' usually begins with an acute onset of high [[fever]], [[chills]] and [[hemorrhage]] observed on [[physical examination]]. Other pertinent findings may include swollen [[joints]], [[weakness]], [[rash]] and [[red eyes]]. Also, the high [[fever]] present in this condition may lead to the development of relative [[bradycardia]], similarly to [[typhoid fever]]. <ref name="FeldmannGeisbert2011">{{cite journal|last1=Feldmann|first1=Heinz|last2=Geisbert|first2=Thomas W|title=Ebola haemorrhagic fever|journal=The Lancet|volume=377|issue=9768|year=2011|pages=849–862|issn=01406736|doi=10.1016/S0140-6736(10)60667-8}}</ref><ref name="FormentyHatz1999">{{cite journal|last1=Formenty|first1=Pierre|last2=Hatz|first2=Christophe|last3=Le Guenno|first3=Bernard|last4=Stoll|first4=Agnés|last5=Rogenmoser|first5=Philipp|last6=Widmer|first6=Andreas|title=Human Infection Due to Ebola Virus, Subtype Côte d'Ivoire: Clinical and Biologic Presentation|journal=The Journal of Infectious Diseases|volume=179|issue=s1|year=1999|pages=S48–S53|issn=0022-1899|doi=10.1086/514285}}</ref><ref name="pmid10667555">{{cite journal| author=Gradon J| title=An outbreak of Ebola virus: lessons for everyday activities in the intensive care unit. | journal=Crit Care Med | year= 2000 | volume= 28 | issue= 1 | pages= 284-5 | pmid=10667555 | doi= | pmc= | url=http://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=10667555  }} </ref>
Ebola is commonly associated with the acute onset of high [[fever]], [[chills]] and [[hemorrhage]] as well as swollen [[joints]], [[weakness]], [[rash]] and [[red eyes]].<ref name="FeldmannGeisbert2011">{{cite journal|last1=Feldmann|first1=Heinz|last2=Geisbert|first2=Thomas W|title=Ebola haemorrhagic fever|journal=The Lancet|volume=377|issue=9768|year=2011|pages=849–862|issn=01406736|doi=10.1016/S0140-6736(10)60667-8}}</ref><ref name="FormentyHatz1999">{{cite journal|last1=Formenty|first1=Pierre|last2=Hatz|first2=Christophe|last3=Le Guenno|first3=Bernard|last4=Stoll|first4=Agnés|last5=Rogenmoser|first5=Philipp|last6=Widmer|first6=Andreas|title=Human Infection Due to Ebola Virus, Subtype Côte d'Ivoire: Clinical and Biologic Presentation|journal=The Journal of Infectious Diseases|volume=179|issue=s1|year=1999|pages=S48–S53|issn=0022-1899|doi=10.1086/514285}}</ref><ref name="pmid10667555">{{cite journal| author=Gradon J| title=An outbreak of Ebola virus: lessons for everyday activities in the intensive care unit. | journal=Crit Care Med | year= 2000 | volume= 28 | issue= 1 | pages= 284-5 | pmid=10667555 | doi= | pmc= | url=http://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=10667555  }} </ref>


===Laboratory Findings===
===Laboratory Findings===
There are no specific laboratory findings of Ebola virus disease. Some nonspecific findings include alterations in the [[white blood cells]] count, blood chemistry tests and liver function tests.
[[Ebola]] infection is associated with nonspecific laboratory abnormalities including alterations in the [[white blood cell]] count, [[blood chemistry tests]] and [[liver function tests]], all of which may contribute to a disruption in the [[thrombosis|clotting]] process and [[bleeding]].


===Other Diagnostic Studies===
===Other Diagnostic Studies===
Antigen-capture enzyme-linked immunosorbent assay ([[ELISA]]) testing, [[IgM]] [[ELISA]], [[polymerase chain reaction]] ([[PCR]]), and [[virus]] isolation can be used to diagnose a case of Ebola within a few days of the onset of [[symptoms]]. Persons tested later in the course of the disease or after recovery can be tested for [[IgM]] and [[IgG]] [[antibodies]]; the disease can also be diagnosed retrospectively in deceased patients by using [[immunohistochemistry]] testing, [[virus]] isolation, or [[PCR]].<ref name=CDC>{{cite web | title = Ebola Hemorrhagic Fever Information Packet  | url = http://www.cdc.gov/ncidod/dvrd/spb/mnpages/dispages/Fact_Sheets/Ebola_Fact_Booklet.pdf }}</ref>
While the diagnosis of Ebola may be suspected based on clinical findings, the diagnosis of [[Ebola]] can be confirmed by [[antigen]]-capture [[enzyme-linked immunosorbent assay]] ([[ELISA]]) testing, [[IgM]] [[ELISA]], [[polymerase chain reaction]] ([[PCR]]), and [[virus]] isolation, within few days of the onset of [[symptoms]]. Persons tested later in the course of the disease, or after recovery, can be tested for [[IgM]] and [[IgG]] [[antibodies]]. The disease can also be diagnosed in deceased patients by using [[immunohistochemistry]] testing, [[virus]] isolation, or [[PCR]].<ref name=CDC>{{cite web | title = Ebola Hemorrhagic Fever Information Packet  | url = http://www.cdc.gov/ncidod/dvrd/spb/mnpages/dispages/Fact_Sheets/Ebola_Fact_Booklet.pdf }}</ref>


==Treatment==
==Treatment==
===Medical Therapy===
===Medical Therapy===
Ebola is potentially lethal and since no approved [[vaccine]] or treatment is available. Treatment is primarily supportive and includes maintaining [[fluids]] and [[electrolytes]] [[homeostasis]], adequate [[oxygen]] levels and [[blood pressure]] and treating any complicating infections.<ref name=CDC>{{cite web | title = Ebola Hemorrhagic Fever Information Packet | url = http://www.cdc.gov/ncidod/dvrd/spb/mnpages/dispages/Fact_Sheets/Ebola_Fact_Booklet.pdf }}</ref> All patients with a confirmed or suspected viral hemorrhagic fever should be put in isolation and adequate contact precautions.<ref name="pmid21084112">{{cite journal| author=Feldmann H, Geisbert TW| title=Ebola haemorrhagic fever. | journal=Lancet | year= 2011 | volume= 377 | issue= 9768 | pages= 849-62 | pmid=21084112 | doi=10.1016/S0140-6736(10)60667-8 | pmc=PMC3406178 | url=http://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=21084112  }} </ref>
The treatment of Ebola infection is primarily supportive and includes maintaining [[fluids]] and [[electrolytes]], [[homeostasis]], adequate [[oxygen]] levels and [[blood pressure]] and treating any complicating superimposed [[infections]].<ref name=CDC>{{cite web | title = CDC Ebola Hemorrhagic Fever Information Packet | url = http://www.cdc.gov/ncidod/dvrd/spb/mnpages/dispages/Fact_Sheets/Ebola_Fact_Booklet.pdf | year = April 2010 }}</ref> All patients with a confirmed or suspected [[viral hemorrhagic fever]] should be put in isolation with adequate contact precautions.<ref name="pmid21084112">{{cite journal| author=Feldmann H, Geisbert TW| title=Ebola haemorrhagic fever. | journal=Lancet | year= 2011 | volume= 377 | issue= 9768 | pages= 849-62 | pmid=21084112 | doi=10.1016/S0140-6736(10)60667-8 | pmc=PMC3406178 | url=http://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=21084112  }} </ref> No vaccine is currently available.


===Primary Prevention===
===Primary Prevention===
[[Transmission]] of [[ebola virus disease]] has only been documented to occur during the [[symptomatic phase]] but not during the [[incubation period]]. If [[transmission]] of [[ebola]] occurs, steps need to be taken to prevent further [[infection]] as well as [[transmission]] to other people. It is important to be able to prevent subsequent [[transmission]] of [[ebola]]. [[Transmission]] of [[ebola]] can be prevented by isolation of [[patient]], wearing a [[HEPA]] or other biosafety mask and by limiting the movement of the [[patient]] from the room to other areas.
The [[transmission]] of Ebola can be limited by implementing preventive measures in both [[endemic]] and nonendemic areas which include isolation of infected patients; using gloves/masks/gowns and other standard barrier precautions; routine hand-washing; careful handling, disposal and/or maintenance of sharp objects; proper waste management and proper handling of human remains after death.


===Future or Investigational Therapies===
===Future or Investigational Therapies===
There are promising results for antisense prevention therapies in monkey studies. Administration of an inhibitor of coagulation (rNAPc2) has demonstrated some benefit in monkey studies. There are non-conclusive results in human survivors from post-exposure [[vaccination]], [[passive immunization]] with blood or serum or with recombinant human [[monoclonal antibodies]].
Although there is no effective human [[vaccine]] against Ebola currently available, there are promising results for [[antisense]] [[prevention]] therapies targeting the Ebola virus in monkey studies. Administration of an inhibitor of [[coagulation]] (rNAPc2) has demonstrated some benefit in monkey studies. There are non-conclusive results in human survivors from post-exposure [[vaccination]], [[passive immunization]] with [[blood]] or [[serum]] or with recombinant human [[monoclonal antibodies]].
 


==References==
==References==
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[[Category:Hemorrhagic fevers]]
[[Category:Hemorrhagic fevers]]
[[Category:Disease]]
[[Category:Disease]]
[[Category:Infectious disease]]

Latest revision as of 17:38, 18 September 2017

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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Guillermo Rodriguez Nava, M.D. [2] Alejandro Lemor, M.D. [3]

Overview

Ebola virus disease (EVD) is one of numerous viral hemorrhagic fevers (VHF). It is a severe, often fatal disease in human and nonhuman primates. Ebola virus is spread by direct contact with the blood or body fluids (such as urine, saliva, feces, vomit and semen) of an infected person or by being exposed to objects that have been contaminated with infected blood or body fluids. The incubation period is usually 8–10 days (rarely ranging from 2 to 21 days). Patients can transmit the virus once symptoms appear and through the later stages of disease, as well as postmortem. Ebola has caused a number of serious and highly publicized outbreaks since its discovery.[1]

Historical Perspective

The Ebola virus was named after the Ebola River Valley in the Democratic Republic of the Congo (formerly Zaïre), near the site of a 1976 outbreak at a mission run by Flemish nuns.[2] Since the initial discovery of the virus, five subtypes have subsequently been identified.

Classification

Ebola virus can be classified into 5 subtypes: Zaïre, Sudan, Reston, Tai (Ivory Coast) and Bundibugyo, according to the place of discovery.

Pathophysiology

The Ebola virus infects the mononuclear phagocyte system, but also other cells such as hepatocytes, spongiocytes, fibroblasts and endothelial cells, inducing tissue necrosis and disrupting the hematological and coagulation systems. The Ebola virus is transmitted by direct contact with infected patients or animals. The natural reservoir has not been identified.[3][4][5][6]

Causes

Ebola infection is caused by a virus that belongs to the family Filoviridae. Three viral subtypes 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.

Differentiating Ebola from other Diseases

Ebola must be differentiated from other diseases that cause hemorrhage and/or high fever as part of their presentation such as Marburg virus, Lassa fever, Typhoid fever and Malaria. The clinician must first rule out other more common causes of the fever before considering a viral hemorrhagic fever (VHF) such as Ebola, and the consideration of a VHF should be based upon epidemiology and demographics as well as sign and symptoms.[7] A VHF such as Ebola, should be suspected in febrile persons who, within 3 weeks before onset of fever, have either: 1) traveled in the specific local area of a country where VHF has recently occurred; 2) had direct unprotected contact with blood, other body fluids, secretions, or excretions of a person or animal with VHF; 3) if the patient had any contact with someone who was ill with fever and bleeding or who died from an unexplained illness with fever and bleeding; 4) had a possible exposure when working in a laboratory that handles hemorrhagic fever viruses; 5) If a fever continues after 3 days of empiric treatment, and if the patient has signs such as bleeding or shock, the clinician must consider a VHF; 6) if no other cause is found for the patient’s signs and symptoms, the clinician must suspect a VHF.

Epidemiology and Demographics

Outbreaks of Ebola have been generally restricted to Africa. Governments and individuals should quickly quarantine the area. Lack of roads and transportation help to contain the outbreak in remote areas. The potential for widespread Ebola virus disease epidemics is considered low due to the high case-fatality rate, the rapidity of demise of patients, and the often remote areas where infections occur.

Risk Factors

The main risk factors for Ebola virus disease are traveling to endemic areas, to be a health professional taking care of infected patients and researchers working with animal models of the Ebola virus disease.[8]

Natural History

Ebola infection rapidly progresses to death in the absence of supportive care. Ebola infection can be complicated by multiorgan failure and shock. The prognosis of Ebola infection is poor, and depends upon the Ebola virus strain. The Zaire Ebola virus has mortality rate as high as 90%.[8]

Diagnosis

History and Symptoms

Ebola causes a variety of symptoms which may include fever, chills vomiting, diarrhea, generalized pain or malaise, and sometimes internal and external bleeding, that follow an incubation period of 2-21 days. These symptoms are common to all species of Ebola virus, but the different species may present with differences in the severity of symptoms.

Physical Examination

Ebola is commonly associated with the acute onset of high fever, chills and hemorrhage as well as swollen joints, weakness, rash and red eyes.[9][10][11]

Laboratory Findings

Ebola infection is associated with nonspecific laboratory abnormalities including alterations in the white blood cell count, blood chemistry tests and liver function tests, all of which may contribute to a disruption in the clotting process and bleeding.

Other Diagnostic Studies

While the diagnosis of Ebola may be suspected based on clinical findings, the diagnosis of Ebola can be confirmed by antigen-capture enzyme-linked immunosorbent assay (ELISA) testing, IgM ELISA, polymerase chain reaction (PCR), and virus isolation, within few days of the onset of symptoms. Persons tested later in the course of the disease, or after recovery, can be tested for IgM and IgG antibodies. The disease can also be diagnosed in deceased patients by using immunohistochemistry testing, virus isolation, or PCR.[8]

Treatment

Medical Therapy

The treatment of Ebola infection is primarily supportive and includes maintaining fluids and electrolytes, homeostasis, adequate oxygen levels and blood pressure and treating any complicating superimposed infections.[8] All patients with a confirmed or suspected viral hemorrhagic fever should be put in isolation with adequate contact precautions.[12] No vaccine is currently available.

Primary Prevention

The transmission of Ebola can be limited by implementing preventive measures in both endemic and nonendemic areas which include isolation of infected patients; using gloves/masks/gowns and other standard barrier precautions; routine hand-washing; careful handling, disposal and/or maintenance of sharp objects; proper waste management and proper handling of human remains after death.

Future or Investigational Therapies

Although there is no effective human vaccine against Ebola currently available, there are promising results for antisense prevention therapies targeting the Ebola virus in monkey studies. Administration of an inhibitor of coagulation (rNAPc2) has demonstrated some benefit in monkey studies. There are non-conclusive results in human survivors from post-exposure vaccination, passive immunization with blood or serum or with recombinant human monoclonal antibodies.

References

  1. "Ebola Cases and Outbreaks - CDC Special Pathogens Branch". Centers for Disease Control and Prevention. Retrieved 2007-12-08.
  2. Bardi, Jason Socrates (2002). "Death Called a River". Scribbs Research Institute. 2 (1). Retrieved 2006-12-08.
  3. Ryabchikova E, Kolesnikova L, Smolina M, Tkachev V, Pereboeva L, Baranova S; et al. (1996). "Ebola virus infection in guinea pigs: presumable role of granulomatous inflammation in pathogenesis". Arch Virol. 141 (5): 909–21. PMID 8678836.
  4. Bray M, Davis K, Geisbert T, Schmaljohn C, Huggins J (1998). "A mouse model for evaluation of prophylaxis and therapy of Ebola hemorrhagic fever". J Infect Dis. 178 (3): 651–61. PMID 9728532.
  5. Connolly BM, Steele KE, Davis KJ, Geisbert TW, Kell WM, Jaax NK; et al. (1999). "Pathogenesis of experimental Ebola virus infection in guinea pigs". J Infect Dis. 179 Suppl 1: S203–17. doi:10.1086/514305. PMID 9988186.
  6. Bray M, Hatfill S, Hensley L, Huggins JW (2001). "Haematological, biochemical and coagulation changes in mice, guinea-pigs and monkeys infected with a mouse-adapted variant of Ebola Zaire virus". J Comp Pathol. 125 (4): 243–53. doi:10.1053/jcpa.2001.0503. PMID 11798241.
  7. "WHO Infection Control for Viral Haemorrhagic Fevers in the African Health Care Setting" (PDF).
  8. 8.0 8.1 8.2 8.3 "CDC Ebola Hemorrhagic Fever Information Packet" (PDF). April 2010.
  9. Feldmann, Heinz; Geisbert, Thomas W (2011). "Ebola haemorrhagic fever". The Lancet. 377 (9768): 849–862. doi:10.1016/S0140-6736(10)60667-8. ISSN 0140-6736.
  10. Formenty, Pierre; Hatz, Christophe; Le Guenno, Bernard; Stoll, Agnés; Rogenmoser, Philipp; Widmer, Andreas (1999). "Human Infection Due to Ebola Virus, Subtype Côte d'Ivoire: Clinical and Biologic Presentation". The Journal of Infectious Diseases. 179 (s1): S48–S53. doi:10.1086/514285. ISSN 0022-1899.
  11. Gradon J (2000). "An outbreak of Ebola virus: lessons for everyday activities in the intensive care unit". Crit Care Med. 28 (1): 284–5. PMID 10667555.
  12. Feldmann H, Geisbert TW (2011). "Ebola haemorrhagic fever". Lancet. 377 (9768): 849–62. doi:10.1016/S0140-6736(10)60667-8. PMC 3406178. PMID 21084112.


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