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Ebola disease: For health professionals and humanitarian aid workers

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Ebola disease and Marburg virus

Ebola and Marburg viruses are negative-stranded ribonucleic acid (RNA) filoviruses in the viral family Filoviridae. The family Filoviridae consists of three genera:

Marburg virus disease and Ebola disease, caused by orthomarburgvirus and orthoebolavirus respectively, spread from person to person by the same mechanisms. These include through direct contact with the blood or other body fluids of a person infected with the virus, from objects or surfaces contaminated with bodily fluids from a person infected with the virus or during preparation of a body for burial. The viruses may also be transmitted in the semen of persons who have recovered from the viruses.

The incubation period and presentation of the illness in humans is similar in both Marburg virus disease and Ebola disease.

There is currently no specified treatment for persons infected with Marburg virus disease or Ebola disease. Early, supportive therapy in appropriate treatment centres is critical for more positive outcomes.

There is no approved vaccine for orthomarburgviruses, although there is a vaccine being used for humanitarian efforts in outbreak situations. However, there is a Health Canada approved vaccine for Ebola virus. For more information regarding the approved vaccine see the section below: Vaccines

The current risk in Canada for Marburg disease is low, while the risk for Ebola disease is very low.

There is limited research on orthomarburgviruses due to the infrequency and size of outbreaks as compared with orthoebolaviruses. Although, the current available evidence suggests that the orthomarburgviruses and orthoebolaviruses have similar characteristics. As such, in the event of a Marburg virus disease outbreak, guidance, tools and resources developed for Ebola disease are appropriate to utilize, including infection prevention and control measures.

Most of the currently available scientific evidence related to Ebola disease comes from experience with Ebola virus disease specifically. What we know from other orthoebolaviruses (Sudan virus, Bundibugyo virus, Taï Forest virus) is based on limited evidence. However, all orthoebolaviruses causing disease in humans likely behave similarly.

Key information

Health professionals in Canada are advised to be vigilant in the recognition, prompt investigation and reporting of patients with:

How to classify cases of Ebola disease

Ebola disease is a severe disease with outbreak case fatality rates estimated to be around 50% (typically ranging between 25 to 90%). Fatal cases tend to have more severe early clinical signs and symptoms. They progress to multi-organ failure and death typically around day 6 to 16.

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:

This may make it more challenging to diagnose early.

Supportive care is the mainstay of treatment for Ebola disease. Early initiation of supportive care has been found to significantly reduce the number of deaths.

Ebola disease is generally limited geographically. The foci of epidemic Ebola disease occur in parts of Sub-Saharan Africa. At this time, no cases of this disease have been reported in Canada.

Statement from Committee to Advise on Tropical Medicine and Travel (CATMAT) Ebola disease prevention, monitoring and surveillance recommendations

Causative agents

Ebola disease is caused by ribonucleic acid viruses of the genus Orthoebolavirus, in the Filoviridae family. To date, there are 6 recognized orthoebolaviruses, but only 4 of them are known to cause Ebola disease in humans:

Ebola virus and Sudan virus have been responsible for the majority of Ebola disease outbreaks to date and they are associated with higher case fatality rates. Bundibugyo virus has caused 2 outbreaks of Ebola disease since its emergence in 2007. It is associated with a lower case fatality rate than Sudan virus and Ebola virus. Taï Forest virus has only been identified as the causative agent for 1 case of Ebola disease, and the individual survived.

Reston virus can cause illness in pigs and non-human primates and the Bombali virus has been identified in insectivorous bats. Neither virus has been associated with disease in humans.

Orthoebolaviruses are zoonotic viruses, and while their reservoir is not currently known, it is thought that fruit bats could be the natural host. Other animals, in particular non-human primates, have been identified as incidental hosts.

Ebolaviruses: Infectious substances pathogen safety data sheet

Classification and nomenclature

New nomenclature was adopted by the World Health Organization in 2019. Further changes were also introduced by the International Committee on Taxonomy of Viruses in 2023. This page uses the updated taxonomy. For more information, refer to:

Genus name: Orthoebolavirus

There are 6 viruses (orthoebolaviruses) belonging to the Orthoebolavirus genus:

Diseases include:

Transmission

Ebola disease outbreaks in humans are typically thought to occur through the introduction of a human case infected through contact with the tissues or body fluids of an infected animal. The virus can then subsequently be spread via person-to-person transmission, leading to an outbreak.

Reactivation of dormant virus from a previously-infected human case has been implicated in some outbreaks.

Person-to-person transmission can occur through:

Orthoebolaviruses are not transmitted between humans through airborne transmission. However, certain medical procedures, such as intubation, may generate small particle aerosols that have the potential to transmit the virus   Orthoebolavirus may remain viable on surfaces and in liquids for several days, dependent on other environmental factors.

For more information: How Ebola disease spreads

Period of communicability

A case becomes infectious at the time of onset of the first symptoms. Infected persons are not thought to be infectious before the onset of symptoms.

The risk of transmission from a case is lower in the early stages of disease when the viral load is lower. The risk of transmission is highest when viral load is greatest, such as when a person is acutely symptomatic with diarrhea, vomiting and/or bleeding.

Cases remain contagious as long as blood and body fluids contain the virus, and this includes the post-mortem period. Direct contact with the body of a deceased Ebola disease case during burial ceremonies has been known to contribute to the transmission of the disease in past outbreaks.

In survivors, orthoebolaviruses can persist for weeks to months in some body fluids and tissues, such as:

For example, the Ebola virus ribonucleic acid has been detected in semen for as long as 18 months after clinical recovery. It is unknown if infectious virus was present in these cases. Potential for transmission after the acute phase of illness is limited to sexual transmission and transmission via breastfeeding.

For more information regarding specimen testing to determine infectiousness of bodily fluids, refer to: Public Health Management of Cases and Contacts of Ebola Disease in the Community Setting in Canada (2024)

Risk factors

Any contact with blood or other body fluids of an infected person or animal and fomites can lead to transmission. Factors associated with a higher risk of exposure to the virus include:

Contacts should be managed according to their risk level, and measures should be implemented for cases and contacts to prevent the spread of Ebola disease.

Note that clinical judgement remains essential for risk assessment and may result in decisions that differ from available recommendations.

Learn more:

Humanitarian aid workers

Humanitarian aid workers returning from an outbreak affected area should follow the guidance provided by their organization.

Under the Quarantine Act, travellers must self-identify to a Canada Border Services Agent on arrival in Canada if they have:

It is also recommended that travellers with a low risk of exposure call the appropriate public health authority during the first business day following arrival in Canada to self-identify.

Risk in Canada

The Public Health Agency of Canada works closely with its national and international partners to:

In Canada, the risk of exposure to a source of Ebola disease is considered to be very low. However, specific occupational groups like laboratory and health care workers may be exposed due to the nature of their work, putting them at a higher risk of exposure. Local transmission of Ebola disease in Canada may also be introduced via exposure following international travel, particularly to areas affected by Ebola disease 27. If this were to occur, public health authorities at all levels of government would be involved in managing the response.

Current outbreaks of Ebola disease (World Health Organization)

Signs and symptoms

Ebola disease has an incubation period ranging between 2 and 21 days, with most cases experiencing onset of symptoms 6 to 10 days after exposure.

Symptoms usually begin with a sudden onset of non-specific symptoms, which include:

About 4 to 5 days after onset, the illness typically progresses to include manifestations such as:

The illness may then progress further to include serious late manifestations. Diarrhea and vomiting are often profuse in later stages of the illness, and can lead to:

These can lead to impaired kidney and liver function. A late manifestation of the illness is usually hemorrhaging, such as:

However, it is not present in all cases.

Severe cases with hemorrhagic symptoms typically have concurrent and significant multisystem and end-organ damage. For example, central nervous system dysfunction and bone marrow suppression (with leukopenia and thrombocytopenia).

Other serious late manifestations that may occur include:

Ebola disease is associated with a high risk of:

This indicates that pregnant people with Ebola disease may experience severe outcomes more frequently than non-pregnant people.

The illness can also be complicated by secondary bacterial infections.

Non-fatal cases of Ebola disease typically begin improving around day 6 to 11 following symptom onset. Fatal cases tend to have more severe early clinical signs and symptoms, and progress to multi-organ failure and death typically around day 6 to 16.  

Full recovery occurs over a long period of time, and this disease may be associated with long-term sequelae that can be severe, including:

Symptoms of Ebola disease are similar to those of other viral haemorrhagic fevers, such as Marburg virus disease and Lassa fever. It's important to consider that a person with suspected or confirmed Ebola disease may have a concurrent infection with other diseases endemic to sub-Saharan Africa such as:

Diagnosis

Laboratory testing, clinical and epidemiological investigation are recommended to properly diagnose Ebola disease. Early diagnosis allows for:

Laboratory testing

The decision for specimen collection and testing should rely on:

The gold standard for confirmatory testing is the detection of virus-specific ribonucleic acid by PCR in clinical sample(s), using 2 independent molecular targets. Other methods that can point to an Ebola disease diagnosis include:

Public Health Agency of Canada Case Definition: Ebola disease outbreak

Differential diagnostic testing is also performed at the National Microbiology Laboratory which can test for other pathogens and co-infections, based on travel, symptoms and exposure history.

Mishandled specimens from patients under investigation for Ebola disease are a serious risk to all including laboratory personnel. There are specific biosafety guidelines that laboratories must follow before accepting samples and proceeding with testing.

Biosafety Guidelines for Laboratories Handling Specimens from Patients under Investigation for Ebola Disease

Virus cultures for orthoebolaviruses should not be attempted outside of the biosafety level 4 containment laboratories at the National Microbiology Laboratory.

For diagnostic or confirmatory services for orthoebolaviruses, liaise with the provincial public health laboratory of your jurisdiction. The provincial public health laboratory should coordinate with the NML laboratory's operations centre director.

The operations centre director will:

National Microbiology Lab (NML) Phone: 1-866-262-8433

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

Recent vaccination can impact diagnostic testing for filoviruses using the National Microbiology Laboratory's molecular testing approaches. For this reason, it is important to inform them of the vaccine status of the person under investigation.

Approaches that may be impacted include:

Public Health Agency of Canada Case Definition: Ebola disease outbreak

Monitoring, surveillance and reporting

Public health authorities are requested to notify the PHAC Health Portfolio Operations Centre (HPOC) at 1-800-545-7661, concurrently with notifications to their provincial and territorial health authority of all PUIs requiring Orthoebolavirus testing within 24 hours of ordering the test, using the Ebola Disease Case Report Form and information available at the time of the initial report. The case report form can be updated as additional information becomes available.

Provinces and territories are required to report cases to the Public Health Agency of Canada by:

  1. contacting the Health Portfolio Operations Centre at 1-800-545-7661
  2. completing an Ebola disease case report form

The patient's clinical history and epidemiological risk for Ebola disease should be included in the report.

Ebola virus disease case report form

Canadian public health authorities monitor and respond, as appropriate, to all events related to Ebola disease. Recommended practices may be adjusted as warranted by specific epidemiological situations.

Viral hemorrhagic fevers, including Ebola disease, have been nationally notifiable in Canada since 2002 (in addition to a brief period from 1979 to 1982).

The Public Health Agency of Canada also reports confirmed cases of Ebola disease to the World Health Organization, as part of Canada's commitments under the International Health Regulations.

International Health Regulations (2005) – Third edition (World Health Organization)

Treatment

Individuals with suspected or confirmed Ebola disease should receive care in appropriately-specialized centres. Strict infection prevention and control precautions ought to be maintained:

Individuals requiring healthcare services as a result of suspected or confirmed Ebola disease should refrain from taking public transit. Provincial and territorial public health authorities can provide information regarding whether a treatment facility has been designated for this purpose in their jurisdiction.

Therapeutics

There is currently no Health Canada-approved treatment for Ebola disease.

However, 2 products are approved by the US Food and Drug Administration for the treatment of Ebola virus (species Orthoebolavirus zairense) 45, 46:

  1. REGN-EB3 (Inmazeb or atolivimab, maftivimab and odesivimab)
  2. mAb114 (Ebanga or ansuvimab)

These treatments have been shown to be moderately effective at reducing mortality in Ebola virus disease patients with lower serum viral loads. Their efficacy has not been established against other orthoebolaviruses. These treatments were formulated against Ebola virus and are therefore not expected to be effective for the treatment of other orthoebolaviruses.

In outbreak situations, investigational therapeutics 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. In the event of a confirmed case of Ebola disease occurring in Canada, the Public Health Agency of Canada would work with the province or territory to provide access to appropriate treatment.

Clinical trials to test the effectiveness of investigational therapeutics typically occur in outbreak settings. The results of clinical trials inform future licensing and recommendations for use of these products.

Supportive care

Supportive treatment is a key component of Ebola disease management which can improve prognosis.

During the 2014 to 2016 epidemic, most Ebola virus disease cases who were treated in the US and Europe received early and aggressive supportive care. Of the 27 confirmed cases treated, 82% survived.

Optimized supportive care for Ebola virus disease: Clinical management standard operating procedures (World Health Organization)

Vaccines

There is currently 1 vaccine approved for Ebola virus disease in Canada (Ervebo, rVSVΔG-ZEBOV-GP vaccine). At this time, the Ervebo® vaccine is not approved nor recommended to prevent disease caused by other orthoebolaviruses, such as:

There are no approved vaccines for other orthoebolaviruses.

Product monograph for Ervebo, rVSVΔG-ZEBOV-GP vaccine (PDF, 1.1 MB)

In November 2022, the Ervebo®vaccine was approved for use in Canada. This vaccine is a live-attenuated, replication-competent recombinant vesicular stomatitis virus-based (rVSV) chimeric-vector vaccine, in which the VSV glycoprotein gene is replaced with the glycoprotein gene of Ebola virus. It is administered as a single dose for protection against Ebola virus (species Orthoebolavirus zairense). Due to significant antigenic differences, this vaccine is not expected to provide significant protection against other orthoebolaviruses 48.

Ervebo®is licensed for use in Canada, but it is not marketed in the country. In the event of a case of Ebola virus disease in Canada, the vaccine may be deemed helpful for outbreak control purposes. Under these circumstances, access to this product will be facilitated by the Public Health Agency of Canada and the relevant provinces and territories.

In areas affected by Ebola virus disease, the vaccine can be offered to:

Due to the limitations of available evidence, uncertainties remain regarding the level, duration and type of protection provided by vaccinations. It is important to note that the individual risk assessment of contacts should not change based on vaccination status

The provision of vaccination against EBOV to Canadian humanitarian workers who travel to Ebola disease-affected areas to provide care to confirmed EBOV cases or their contacts or engage in safe burials, is the responsibility of the organization delivering these services.

Learn more:

Infection prevention and control

Observe these key infection prevention and control measures in healthcare settings where you anticipate contact with:

Carry out routine practices, such as proper hand hygiene and proper use of personal protective equipment.

Use a point-of-care risk assessment approach prior to every interaction with a symptomatic patient (person under investigation or confirmed). This will support the use of additional infection prevention and control measures where indicated.

Additional precautions:

Implement strategies to prevent aerosol generation unless absolutely necessary.

If the patient is clinically unstable or an aerosol-generating medical procedure is required, change into:

Observe these precautions until:

Following confirmation that the virus is no longer circulating in the blood, consultation between experts in infection prevention and control, infectious diseases and public health should be done before discontinuing precautions.

For detailed recommendations on infection prevention and control measures for Ebola disease, refer to:

Related links

These links provide information on topics such as:

Some links use the term Ebola virus disease or discuss Ebola virus specifically. The majority of the information available in these documents remains relevant in the context of Ebola disease more broadly.

Infection prevention and control

Border and travel health

Ebola vaccines

Public health management

Related websites

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2025-01-27