Ebola disease: For health professionals and humanitarian aid workers
On this page
- What health professionals and humanitarian aid workers need to know about Ebola disease
- History and context
- Causative agents
- Risk groups
- Clinical features
What health professionals and humanitarian aid workers need to know about Ebola disease
Health professionals in Canada are advised to be vigilant in the recognition, reporting and prompt investigation of patients with a history of potential exposure to a source of an ebolavirus (such as travel to an outbreak affected area) and symptoms of:
- Ebola disease (EBOD)
- similar diseases that can cause viral hemorrhagic fevers (VHFs)
Consult the Ebola disease outbreak case definition.
Ebola disease is a severe disease with an estimated case fatality rate of around 50%. The incubation period ranges from 2 to 21 days and individuals don’t spread the disease prior to the onset of symptoms. Manifestations of Ebola disease may be non-specific (such as fever, fatigue, muscle pain, headache, sore throat, vomiting, diarrhea, rash), which may make it more challenging to diagnose early.
Supportive care is the mainstay of treatment for EBOD. Early initiation of supportive care has been found to significantly reduce the number of deaths.
For details on preventive measures and the monitoring and surveillance of returning travellers, review the Committee to Advise on Tropical Medicine and Travel's (CATMAT) statement on Ebola Virus Disease Prevention, Monitoring and Surveillance Recommendations. Note that this document refers to EBOD caused by Ebola virus specifically, although many sections can still be used for information on EBOD in general. Also refer to the Related links section for links to additional documents.
At this time, no cases of this disease have been reported in Canada.
New nomenclature was recently adopted by the World Health Organization and is being used on this webpage. For more information refer to the following article: New filovirus disease classification and nomenclature.
Note that the information below is focused on Ebola virus disease, and it is currently under review.
History and context
Ebola disease (EBOD) (the generic term for all diseases caused by the members of the genus Ebolavirus formerly known as Ebola Hemorrhagic Fever) is a rare, severe, acute viral illness first identified over 40 years ago. These viruses can cause disease in human and non-human primates (such as monkeys, gorillas, chimpanzees) and can infect other animals (such as fruit bats, forest antelope, pigs).
Ebola disease is generally limited geographically, occurring primarily in outbreak-prone areas of sub-Saharan Africa. Historically, between 1976 and 2012, sporadic cases and outbreaks of Ebola disease were reported in several African countries (Côte d'Ivoire, DRC, Gabon, Republic of Congo, South Africa, South Sudan and Uganda), averaging fewer than 150 cases per outbreak, and having case fatality rates around 50% (range: 25 to 90%)Footnote 1Footnote 2.
The largest recorded outbreak of Ebola disease to date began in late 2013, with initial cases reported in Guinea, followed by spread to other countries in West Africa - Liberia, Sierra Leone, Senegal, Mali, and Nigeria. The Makona strain of Ebola virus (EBOV), belonging to the Zaire ebolavirus species, was identified as the causative agent of the outbreakFootnote 3. Overall, the 2014-16 West Africa outbreak resulted in over 28,500 cases and 11,300 deathsFootnote 4.
During the 2014-16 West Africa Ebola disease outbreak, imported cases were identified in other countries in Africa, as well as locations in Europe and North AmericaFootnote 5Footnote 6Footnote 7Footnote 8Footnote 9. The occurrence of secondary transmission outside of the affected areas in Africa was also documented, although it was very limitedFootnote 8.
In September 2022, an outbreak of Sudan virus disease (SVD) was announced by Uganda health authorities. This was the first outbreak of SVD in Uganda since 2012. No confirmed cases related to this outbreak were reported outside of Uganda and it was declared over in January 2023.
To date, no cases of Ebola disease have ever been identified in Canada.
Ebola disease (EBOD) is caused by ribonucleic acid (RNA) viruses that are members of the genus Ebolavirus, a member of the Filoviridae family. To date, there are 6 recognized ebolavirusesFootnote 10Footnote 11Footnote 12.
- Ebola virus (species Zaire ebolavirus) or EBOV
- Sudan virus (species Sudan ebolavirus) or SUDV
- Bundibugyo virus (species Bundibugyo ebolavirus) or BDBV
- Taï Forest virus (species Taï Forest ebolavirus) or TAFV
- Reston virus (species Reston ebolavirus) or RESTV
- Bombali virus (species Bombali ebolavirus) or BOMV
Among the 6 viruses identified to date, only 4 are known to cause illness in people: EBOV, SUDV, TAFV, and BDBV. While these 4 viruses are all pathogenic to humans, EBOV and SUDV are considered especially virulent, and are associated with higher case fatality ratesFootnote 13. In contrast, RESTV is known to cause illness in non-human primates and pigs, but appears to be non-pathogenic in humans.
In 2018 a potential new virus called the Bombali virus (BOMV), belonging to the tentatively named Bombali ebolavirus species, was identified in insectivorous bats roosting inside people's homes in Sierra Leone. Very little is known about BOMV at this time; investigations are ongoing.
Viruses causing Ebola disease are believed to persist within forest-dwelling fruit bats (although live virus has never been found in any fruit bat species) in AfricaFootnote 14Footnote 15. Other animals, in particular non-human primates, have been identified as incidental hosts (not reservoirs).
Additional information is available from the Ebolaviruses: Infectious substances Pathogen Safety Data Sheet.
Outbreaks in humans can occur through initial exposure to either the reservoir population or an intermediate infected host (generally, non-human primates such as monkeys or gorillas), with subsequent person-to-person transmission.
Person-to-person transmission can occur though:
- direct contact with blood and/or other body fluids (such as feces, urine, emesis, saliva, sweat, breast milk, semen) from an infected symptomatic person or dead body
- indirect contact with surfaces and fomites (such as needles) that are contaminated with these fluids
Infected persons are not considered to be infectious before the onset of symptoms. The risk of transmission is highest when the viral load is greatest, usually when a person is acutely unwell. Cases remain communicable as long as blood and body fluids contain the virusFootnote 16, including the post-mortem periodFootnote 2Footnote 17.
During clinical recovery, ebolaviruses can also persist for weeks to months in some body fluids (such as semen, urine and breast milk)Footnote 16Footnote 18Footnote 19Footnote 20Footnote 21Footnote 22Footnote 23. For example, the virus has been detected in semen for as long as 18 months laterFootnote 24Footnote 25. The virus can also persist in certain areas of the body (such as the eyes, central nervous system), even after the patient recovers from illnessFootnote 19. With the exception of the potential for sexual transmission of the virus during recovery, ebolaviruses cannot be spread to others by an asymptomatic person.
Viruses causing Ebola disease are not transmitted between humans through airborne transmission or casual interactions. Examples of casual interactions include sharing a seating area on public transportation or sitting in the same waiting room, but with no direct or indirect contactFootnote 26.
While not normally transmissible by the airborne route, certain medical procedures, such as intubation, may generate virus-carrying particles.
Ebola disease has an incubation period ranging between 2 and 21 days, with most cases experiencing onset of symptoms 4 to 10 days after exposureFootnote 27.
Activities associated with a higher risk of exposure to the virus include:
- provision of care to Ebola disease cases who are ill, without proper and consistent use of appropriate personal protective equipment
- unprotected sexual contact with an Ebola disease case who is acutely ill, or during their recovery
- pregnancy (from mother to child)
- participation in unsafe burial practices, including the preparation of the deceased for burial
- handling and/or consumption of wild animals hunted or gathered for food (bushmeat) in affected areas
For the purposes of implementing public health measures contacts of Ebola disease cases are classified according to their risk of exposure.
A high-risk of exposure includes any of the following:
- Direct physical contact, without adhering to recommended infection, prevention and control (IPC) precautions or due to a breach in IPC precautions, with:
- the body surface, mucous membranes or body fluids of a symptomatic Ebola disease case, or their dead body
- any other known source of ebolaviruses (such as contaminated medical instruments, objects or environmental surfaces)
- Unprotected sexual contact with an acute or convalescent cases of Ebola disease.
A low-risk of exposure includes any of the following:
- Physical contact, while adhering to recommended IPC precautions and no known breach in IPC precautions, with:
- the body surface, mucous membranes or body fluids of a symptomatic Ebola disease case, or their dead body
- any other known source of ebolaviruses (such as contaminated medical instruments or environmental surfaces)
- Having only casual interactions and no direct (unprotected body surface to body surface) physical contact with an Ebola disease case or their body fluids. Examples of casual interactions include sharing a seating area on public transportation or sitting in the same waiting room.
Humanitarian aid workers
Humanitarian aid workers returning from an outbreak affected area should follow the guidance provided by their organization, including:
- calling the appropriate public health authority during the first business day following arrival in Canada to self-identify, even if they have no exposures or a low risk of exposure
- self-identifying to a Canada Border Services Agent on arrival in Canada, if they have a high risk of exposure or have Ebola disease compatible symptoms
Risk in Canada
The Public Health Agency of Canada (PHAC) works closely with its national and international partners to track and monitor Ebola disease activity around the world, and assesses the risks of Ebola disease to Canadians on an ongoing basis. Information on current outbreaks of Ebola disease can be found on the World Health Organization website.
Although the risk of exposure to ebolaviruses in Canada is considered to be low, it is possible that the introduction of a case connected to an outbreak in an Ebola disease-affected area could occurFootnote 28. If this were to occur, public health authorities at all levels of government would be involved in managing the response.
Symptoms usually begin with a sudden onset of flu-like symptoms, such as fever, myalgia, severe headache and malaise, typically followed by worsening gastrointestinal symptoms (such as anorexia, nausea, abdominal discomfort, vomiting and diarrhea). Other symptoms include pharyngitis and conjunctival injection. A nonpruritic, erythematous, maculopapular rash that involves neck, trunk, and arms, may develop in 25% to 52% of patients by days 5 to 7Footnote 29Footnote 30Footnote 31.
Diarrhea and vomiting can be profuse in later stages of the illness. The disease can progress to severe volume depletion, electrolyte abnormalities, wasting, and shock. In fewer than half of cases, hemorrhage may occur as a late manifestation, usually from venipuncture sites through the gastrointestinal tract or other mucosa (such as gums, nose). Secondary bacterial infections may also occur. Case fatality in humans can range from 25 to 90%.
Non-fatal cases have fever for several days and typically begin improving around day 6 to 11Footnote 27. Full recovery occurs over a long period of time, and this disease may be associated with long-term sequelae such as myelitis, recurrent hepatitis, psychosis, or uveitisFootnote 18.
Clinicians should remain vigilant and obtain a detailed travel history from patients presenting with a clinical picture suggestive of Ebola disease. Clinical evaluation, laboratory testing and epidemiological investigation are recommended to properly diagnose Ebola disease cases and ensure management of contacts and the immediate environment.
Laboratory methods for confirming a case of Ebola disease are based on isolation of the virus, detection of its RNA or components, and/or demonstration of antibodies against it. While the gold standard for confirmatory testing is a PCR positive result by 2 molecular targets, all sufficient methods and specimens for confirming a case are defined in detail in the Ebola disease outbreak case definition.
Laboratories receiving specimens from patients under Ebola investigation should know that mishandled specimens are a serious risk to laboratory personnel. Before testing occurs, consult the Biosafety Guidelines for Laboratories Handling Specimens from Patients Under Investigation for Ebola Disease.
The decision for specimen collection and testing should be predicated on:
- the clinical status of the patient
- the risk of exposure to a source of an ebolavirus
Virus cultures for ebolaviruses should not be attempted outside of the biosafety level 4 containment laboratories at the National Microbiology Laboratory (NML).
For diagnostic or confirmatory services for Ebola disease, liaise with the provincial public health laboratory of your jurisdiction. The provincial public health laboratory should coordinate with the NML Operations Centre Director at 1-866-262-8433. This number is staffed at all times.
Access the NML requisition and fact sheet for molecular testing of Ebolaviruses.
The NML Operations Centre Director will:
- work with the requesting provincial or territorial jurisdiction to activate the Emergency Response Assistance Plan
- connect you with the appropriate subject matter expert if you require assistance with:
- the shipping process
- sample requirements
- sample packaging
- sample shipping conditions
Alongside laboratory service requests for Ebola disease or other VHFs, provinces and territories should report a patient's clinical history of illness to the Health Portfolio Operations Centre. Contact the centre at 1-800-545-7661.
Clarification or further information may be requested from the patient's clinician to optimize delivery of requested laboratory services.
Diagnostic testing and possible impacts of vaccination
Diagnostic testing for Ebola virus using the molecular testing approaches of the NML would not be impacted by recent vaccination with the rVSV-ZEBOV vaccine. The molecular targets for this test (the Ebola virus NP and L genes) are not found in the rVSV-ZEBOV vaccine, which is based on the Ebola virus glycoprotein or GP gene. Testing in other countries may use the GeneXpert platform which uses the NP and GP genes as targets. As such, it is conceivable that a recent vaccine recipient would be NP negative but GP positive. If the history of vaccination was not readily available, this could cause uncertainty. The gold standard for diagnosis remains being positive by 2 molecular targets, but a diagnostic result positive only by the GP gene would warrant repeat testing and other investigations. This would include re-testing and confirmation at the NML. To note, serologic testing cannot currently distinguish between vaccinations and naturally acquired infections.
Patients under investigation for Ebola disease should be reported immediately to local public health authorities. This is a requirement as per jurisdictional protocols in the respective Canadian province or territory. The national Ebola virus disease case report form is available online, including instructions for reporting.
A patient's clinical history of illness should be reported to PHAC’s Health Portfolio Operations Centre. Provinces and territories can contact the centre at 1-800-545-7661. They should also fill out the case report form at the time of the initial report.
Canadian monitoring, surveillance and reporting
Canadian public health authorities monitor and respond, as appropriate, to all Ebola disease-related events and adjust recommended practices in Canada as required.
Viral hemorrhagic fevers, including Ebola disease, have been nationally notifiable in Canada since 2002 (in addition to a brief period from 1979 to 1982). A specific Ebola disease outbreak case definition was developed during the 2014-16 West Africa outbreak and has been updated to facilitate reporting as part of public health response activities in Canada.
PHAC, on behalf of the Government of Canada, would also report confirmed cases to the World Health Organization, as part of Canada's commitments under the International Health Regulations (2005).
Cases should receive care in highly specialized centres, in order to ensure appropriate supportive care (maintaining blood pressure, electrolyte balance and organ systems function) under strict infection prevention control management. Provincial and territorial public health authorities can provide information regarding whether a treatment facility has been designated for this purpose in their jurisdiction. Consult the Ebola Clinical Care Guidelines: A Guide for Clinicians in Canada (PDF) for more information.
There is currently no Health Canada approved treatment for Ebola disease. A number of investigational therapeutics, namely antivirals and monoclonal antibodies, are currently under development.
Although clinical trials for some of these investigational therapies have shown positive results, none have yet reached the point of application for approved use in Canada. These include the monoclonal antibody cocktails (such as ZMapp, REGN3470-3471-3479, mAb 114), as well as antiviral medications (such as Favipiravir, GS-5734).
If a confirmed case of Ebola disease occurs in Canada the PHAC, in coordination with the province or territory, will provide guidance to the treating physician regarding access to investigational products, including monoclonal antibodies and vaccine, through the appropriate regulatory mechanism.
In outbreak situations, investigational monoclonal antibody preparations have been used under an ethical framework developed by the World Health Organization called the Monitored Emergency Use of Unregistered and Investigational Interventions. The framework is not designed to evaluate the drugs but to provide treatment on compassionate grounds.
Clinical trials to test the effectiveness of some new, investigational monoclonal antibody preparations are occurring in outbreak settings. The results of clinical trials will inform future licensing and recommendations for use of these products.
There is currently no approved vaccine for Ebola disease in Canada. An investigational vaccine (rVSV-ZEBOV-GP, Merck) for Ebola virus (species Zaire ebolavirus) has completed early stage investigational trials, and has been available on compassionate grounds in recent outbreaks (West Africa 2014 to 2016, DRC 2018). The vaccine may also be offered to front-line health care and humanitarian workers in areas affected by Ebola disease caused by Ebola virus as part of an outbreak management strategy.
The vaccine isn't approved or marketed in Canada. In the event of a Canadian case, the vaccine may be deemed helpful for outbreak control purposes. Under these circumstances, access to this product will be facilitated by PHAC through the appropriate regulatory mechanism.
The following links provide information on topics such as infection prevention and control, border and travel health, Ebola vaccines, and public health management. You will note that many links use the term “Ebola virus disease” or discuss Ebola virus specifically. The majority of the information available in these documents can still be useful in the context of Ebola disease in general.
Infection prevention and control
Border and travel health
- Committee to Advise on Tropical Medicine and Travel (CATMAT) statement: Ebola Virus Disease Prevention, Monitoring and Surveillance Recommendations
- Environmental sanitation practices to control the spread of communicable disease in passenger conveyances and terminals
- Guidance for Airline Cabin Crews, Cleaning Personnel and Cargo Personnel: How to Protect Yourself and Others from Ebola Virus Disease
Public health management
- World Health Organization: Ebola virus disease
- U.S. Centers for Disease Control and Prevention: Ebola
- European Centre for Disease Prevention and Control: Ebola virus disease
- Canadian Association of Emergency Physicians
- Association of Medical Microbiology and Infectious Disease Canada
- Canadian Critical Care Society
- Footnote 1
40 Years of Ebola Virus Disease around the World [Internet]. [updated June 20, 2018; ]. Available from: https://www.cdc.gov/vhf/ebola/history/chronology.html.
- Footnote 2
Ebola virus disease - Fact Sheet [Internet]. [updated 12 February 2018; ]. Available from: http://www.who.int/news-room/fact-sheets/detail/ebola-virus-disease.
- Footnote 3
Baize S, Pannetier D, Oestereich L, Rieger T, Koivogui L, Magassouba N, et al. Emergence of Zaire Ebola virus disease in Guinea. N Engl J Med. 2014 Oct 9;371(15):1418-25.
- Footnote 4
Situation Report. Ebola Virus Disease (10 June 2016) [Internet].; 2016 . Available from: http://apps.who.int/iris/bitstream/handle/10665/208883/ebolasitrep_10Jun2016_eng.pdf?sequence=1
- Footnote 5
Centers for Disease Control and Prevention. Lack of secondary transmission of ebola virus from healthcare worker to 238 contacts, United Kingdom, December 2014. EID. 2017;23(12).
- Footnote 6
Disease outbreak news. Ebola virus disease - Italy [Internet].; 2015 . Available from: http://www.who.int/csr/don/13-may-2015-ebola/en/.
- Footnote 7
Chevalier MS, Chung W, Smith J, Weil LM, Hughes SM, Joyner SN, et al. Ebola virus disease cluster in the United States--Dallas County, Texas, 2014. MMWR Morb Mortal Wkly Rep. 2014 Nov 21;63(46):1087-8.
- Footnote 8
Disease Outbreak news. Ebola virus disease - Spain. [Internet].; 2014 [updated 9 October 2014; ]. Available from: http://www.who.int/csr/don/09-october-2014-ebola/en/.
- Footnote 9
Disease outbreak news. Ebola virus disease - United Kingdom [Internet].; 2014 [updated 30 December 2014; ]. Available from: http://www.who.int/csr/don/30-december-2014-ebola/en/.
- Footnote 10
Virus Taxonomy. Ebolavirus. [Internet].; 2013 . Available from: http://www.ictvonline.org/virusTaxonomy.asp.
- Footnote 11
Sanchez A. Filoviridae: Marburg and Ebola Viruses. In: Knipe D, Howley P, editors. Fields virology. 4th ed. Philadelphia, PA.: Lippencott-Ravenpp; 2001. p. 1279-304.
- Footnote 12
Takada A, Kawaoka Y. The pathogenesis of Ebola hemorrhagic fever. Trends Microbiol. 2001 Oct;9(10):506-11.
- Footnote 13
Lefebvre A, Fiet C, Belpois-Duchamp C, Tiv M, Astruc K, Aho Glele LS. Case fatality rates of Ebola virus diseases: a meta-analysis of World Health Organization data. Med Mal Infect. 2014 Sep;44(9):412-6.
- Footnote 14
Leroy EM, Kumulungui B, Pourrut X, Rouquet P, Hassanin A, Yaba P, et al. Fruit bats as reservoirs of Ebola virus. Nature. 2005 Dec 1;438(7068):575-6.
- Footnote 15
Leroy EM, Epelboin A, Mondonge V, Pourrut X, Gonzalez JP, Muyembe-Tamfum JJ, et al. Human Ebola outbreak resulting from direct exposure to fruit bats in Luebo, Democratic Republic of Congo, 2007. Vector Borne Zoonotic Dis. 2009 Dec;9(6):723-8.
- Footnote 16
Expert Working Group for the Canadian Guidelines on Sexual Transmitted Infections. EWG Statement on Sexual Transmission of Ebola Virus. Unpublished. August 2014.
- Footnote 17
Chertow DS, Kleine C, Edwards JK, Scaini R, Giuliani R, Sprecher A. Ebola virus disease in West Africa--clinical manifestations and management. N Engl J Med. 2014 Nov 27;371(22):2054-7.
- Footnote 18
Moreau M, Spencer C, Gozalbes JG, Colebunders R, Lefevre A, Gryseels S, et al. Lactating mothers infected with Ebola virus: EBOV RT-PCR of blood only may be insufficient. Euro Surveill. 2015 Jan 22;20(3).
- Footnote 19
Interim guidance for management of survivors of Ebola virus disease in U.S. healthcare settings [Internet].; 2018 . Available from: https://www.cdc.gov/vhf/ebola/clinicians/evaluating-patients/guidance-for-management-of-survivors-ebola.html.
- Footnote 20
Kreuels B, Wichmann D, Emmerich P, Schmidt-Chanasit J, de Heer G, Kluge S, et al. A case of severe Ebola virus infection complicated by gram-negative septicemia. N Engl J Med. 2014 Dec 18;371(25):2394-401.
- Footnote 21
Bausch DG, Towner JS, Dowell SF, Kaducu F, Lukwiya M, Sanchez A, et al. Assessment of the risk of Ebola virus transmission from bodily fluids and fomites. J Infect Dis. 2007 Nov 15;196 Suppl 2:S142-7.
- Footnote 22
Rowe AK, Bertolli J, Khan AS, Mukunu R, Muyembe-Tamfum JJ, Bressler D, et al. Clinical, virologic, and immunologic follow-up of convalescent Ebola hemorrhagic fever patients and their household contacts, Kikwit, Democratic Republic of the Congo. Commission de Lutte contre les Epidemies a Kikwit. J Infect Dis. 1999 Feb;179 Suppl 1:S28-35.
- Footnote 23
Thorson A, Formenty P, Lofthouse C, et al. Systematic review of the literature on viral persistence and sexual transmission from recovered Ebola survivors: evidence and recommendations. BMJ Open 2016;6:e008859. doi:10.1136
- Footnote 24
Subissi L, Keita M, Mesfin S, Rezza G, Diallo B, Van Gucht S, et al. Ebola Virus Transmission Caused by Persistently Infected Survivors of the 2014-2016 Outbreak in West Africa. J Infect Dis. 2018 Jun 18.
- Footnote 25
Subtil F, Delaunay C, Keita AK, Sow MS, Toure A, Leroy S, et al. Dynamics of Ebola RNA Persistence in Semen: A Report From the Postebogui Cohort in Guinea. Clin Infect Dis. 2017 Jun 15;64(12):1788-90.
- Footnote 26
Ebola situation assessment. What we know about transmission of the Ebola virus among humans [Internet].; 2014 [updated 6 October 2014; ]. Available from: http://www.who.int/mediacentre/news/ebola/06-october-2014/en/.
- Footnote 27
Feldmann H, Geisbert TW. Ebola haemorrhagic fever. Lancet. 2011 Mar 5;377(9768):849-62.
- Footnote 28
Undurraga EA, Carias C, Meltzer MI, Kahn EB. Potential for broad-scale transmission of Ebola virus disease during the West Africa crisis: lessons for the Global Health security agenda. Infect Dis Poverty. 2017 Dec 1;6(1):159,017-0373-4.
- Footnote 29
Kortepeter MG, Bausch DG, Bray M. Basic clinical and laboratory features of filoviral hemorrhagic fever. J Infect Dis. 2011;204(Suppl 3):S810-6.
- Footnote 30
Bwaka MA, Bonnet MJ, Calain P, Colebunders R, De Roo A, Guimard Y, et al. Ebola hemorrhagic fever in Kikwit, Democratic Republic of the Congo: Clinical observations in 103 patients. J Infect Dis. 1999;179(Suppl 1):S1-7.
- Footnote 31
Formenty P, Hatz C, Le Guenno B, Stoll A, Rogenmoser P, Widmer A. Human infection due to Ebola virus, subtype Côte d'Ivoire: Clinical and biologic presentation. J Infect Dis. 1999;179(Suppl 1):S48-53.
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