Public Health Agency of Canada Case Definition: Ebola disease outbreak

A person with Ebola disease-compatible symptoms is defined as:

An individual presenting with fever (temperature ≥ 38.0 degrees Celsius) OR at least one of the following symptoms/signs:

• subjective fever
• malaise
• myalgia
• headache
• arthralgia
• fatigue
• loss of appetite
• conjunctival redness
• sore throat
• chest pain
• abdominal pain
• nausea
• vomiting
• diarrhoea that can be bloody
• haemorrhage
• erythematous maculopapular rash on the trunk

Epidemiological Risk Factors are defined as:

• Individual who cared for a case of Ebola disease
• Laboratory worker handling ebolavirus or processing body fluids from a case of Ebola disease
• Individual who spent time in a healthcare facility in an Ebola disease affected area where cases of Ebola disease are being treated
• Sexual contact with an Ebola disease case
• Close contact in households, healthcare facilities, or community settings with a person with Ebola disease while the person was symptomatic - close contact is defined as being for a prolonged period of time within approximately 2 meters (6 feet) of a person with Ebola disease
• Contact with any human remains of a case of Ebola disease OR contact with human remains in an Ebola disease affected area
• Contact with bats, primates or wild animal bush meat from Ebola disease affected areas
• A travel history to an Ebola disease affected area within 21 days

Person Under Investigation (PUI)

A person with Ebola disease-compatible symptoms (as defined above) AND

• A travel history to an Ebola disease affected area within 21 days of symptom onset OR exposure to one or more of the epidemiological risk factors (as defined above) within 21 days of symptom onset,
• With or without pending laboratory results for Ebola disease.

Confirmed Case

A person with laboratory confirmation of ebolavirus infection using at least one of the methods below:

• Isolation and identification of virus from an appropriate clinical specimen (e.g., blood, serum, tissue, urine specimens, throat secretions or other body fluids) (performed at the National Microbiology Laboratory); OR
• Detection of virus-specific RNA by reverse-transcriptase PCR from an appropriate clinical specimen (e.g., blood, serum, tissue, other body fluids) using two independent gene targets AND confirmed by the National Microbiology Laboratory; OR
• Demonstration of virus antigen in tissue (e.g., skin, liver or spleen) by immunohistochemical or immunofluorescent techniques AND another test (e.g., PCR); OR
• Demonstration of specific IgM OR IgG antibody by EIA, immunofluorescent assay or Western Blot by the National Microbiology Laboratory or an approved WHO collaboration centre; OR
• Demonstration of a fourfold rise in IgG titre by EIA, immunofluorescent assay from an acute vs. a convalescent serum sample (performed at the National Microbiology Laboratory).

A note on diagnostic testing and possible impacts of vaccination:

Diagnostic testing for filoviruses (such as Ebola, Sudan and Marburg viruses) using the molecular testing approaches of the National Microbiology Laboratory may be impacted by recent vaccination. For this reason, it is important to inform the NML of the vaccine status of the person under investigation (PUI).

The main vaccine component that is reactive in filovirus vaccine platforms usually contains the GP gene (e.g. the approved rVSV-EBOV vaccine – Ervebo has the Ebola GP gene). As such, a recently vaccinated person may test positive for the GP gene target.

• Although the gold standard for confirmatory testing is the detection of virus-specific RNA by PCR using 2 independent molecular targets (NP, L or GP gene), if the history of vaccination was not readily available, a diagnostic result of singularly the GP gene would warrant repeat testing and other investigations. This would include re-testing and confirmation at the National Microbiology Laboratory. Similarly, testing using the GeneXpert platform which uses the NP and GP genes for Ebola virus as targets may also be affected.
• Serologic testing cannot currently distinguish between vaccinations and naturally acquired infections and would also have to be interpreted in context of vaccination.

Please note that the Ervebo vaccine is only effective against Ebola virus (formerly Zaire ebolavirus) and is not effective against Sudan virus (SUDV), Marburg virus (MARV) or other known filoviruses.