Viral Haemorrhagic Fever including Ebola Virus Disease
Viral hemorrhagic fevers (VHF)s, including Ebola virus disease (EVD), should be initially suspected in all patients with fever and relevant travel history or epidemiological exposure within 21 days prior to illness onset. Relevant travel history includes travel to any geographic area where VHF outbreaks are occurring, including EVD outbreaks. Additionally, VHFs should be suspected in patients with a compatible clinical illness who have travelled within 21 days to any country where sporadic cases of VHF occur.
It is important that other more common and potentially fatal diseases including malaria, typhoid fever, and bacteremia are considered in the differential diagnosis of patients presenting with suspected VHF. Co-infection with Ebola virus and malaria, as well as other pathogens, has been described.
A clinical assessment of risk of VHF, including risk factors of exposure, clinical status and consideration of differential diagnoses is required prior to requesting VHF testing. PHO will test specific VHF pathogen(s) based on the geographical and epidemiological exposure and clinical presentation – individual VHF pathogen(s) to be tested will be decided following consultation between the PHO microbiologist and the requesting healthcare providers.
Uganda officially declared an EVD outbreak on September 20, 2022 and the causative agent is the Sudan ebolavirus. Since the outbreak onset, there have been cases reported and confirmed in various districts in Uganda. For further information, please see this statement from the World Health Organization.
As of November 14, 2022, PHO’s laboratory will perform the Ebolavirus PCR assay to detect the Sudan ebolavirus species. PHO’s laboratory will provide a preliminary result for specimens received from patients with suspected Sudan ebolavirus infection; specimens will also be referred to the National Microbiology Laboratory (NML) in Winnipeg for parallel testing. Please refer to NML’s Guide to Services - Molecular Detection of Ebola virus for more information including turn around time.
IMPORTANT INSTRUCTIONS (Read before proceeding)
If a viral haemorrhagic fever (VHF) including Ebola virus disease (EVD) is suspected, immediately
- Inform your local/hospital infection prevention and control team, occupational health and safety team and an infectious diseases specialist.
- Inform your local/hospital laboratory management and microbiologist.
- Inform your local public health unit AND
- Following a clinical assessment of risk for EVD and/or other VHFs, consult with a PHO Microbiologist available through the PHO Customer Service Centre at 416-235-6556/1-877-604-4567, after-hours 416-605-3113 to request VHF including EVD testing (and concomitant malaria testing if required).
- VHF testing including EVD testing requires the concurrence of a PHO Microbiologist.
Do not collect specimens for microbiological examination before consulting with a PHO Microbiologist.
A wide range of viruses can cause VHF. Examples of such viruses include, but are not limited to Ebola, Crimean-Congo hemorrhagic fever, Lassa, Marburg and Rift Valley fever virus.
For more information on Ebola and other VHFs including testing recommendations, enhanced precautions, and shipping, visit:
|Test Requested||Required Requisition(s)||Specimen Type||Minimum Volume||Collection Kit|
Viral Haemorrhagic Fever (VHF) testing including for Ebola virus disease
2.0 ml per tube
2 EDTA blood tubes
Submission and Collection Notes
Do not collect specimens for microbiological examination before consulting with the PHO Microbiologist. VHF testing, including for EVD, requires the concurrance of a PHO Microbiologist. If testing is agreed to, PHO's laboratory will then provide the submitter with further direction about next steps.
2 EDTA tubes are required for VHF testing and shipping to NML as needed. There will be no aliquoting of samples until VHF is ruled out.
Test Frequency and Turnaround Time (TAT)
Testing for EVD and other VHFs is performed STAT. The actual turnaround time during a specific response will be determined at the time.
As of April 29, 2019, Zaire ebolavirus, Bundibugyo ebolavirus, Crimean-Congo hemorrhagic fever virus, Lassa fever virus, Marburg virus and Rift Valley fever virus PCR testing is performed at PHO’s laboratory in Toronto. In accordance with federal guidelines, positive or indeterminate results are provisional until confirmed by the National Microbiology Laboratory (NML). Depending on the prevalence and of a particular virus at the time of testing, and the clinical features of the individual case, negative test results may be reported as final by PHO laboratory, or alternately be retested at NML for final reporting. The reporting plan will be communicated to stakeholders at the time of testing.
As of November 14, 2022, Sudan ebolavirus PCR testing is performed at PHO’s laboratory in Toronto. A preliminary report will be issued by PHO’s laboratory and specimens will be forwarded to NML for parallel testing regardless of PHO’s preliminary results.
Results are reported to the ordering physician or health care provider as indicated on the requisition. Test results are also reported to the Medical Officer of Health as per Health Protection and Promotion Act.
VHF real-time PCR is performed using a protocol validated at NML, and verified for clinical testing at PHO laboratory. The protocol tests for two gene targets per viral agent: Zaire ebolavirus, Bundibugyo ebolavirus, Crimean-Congo hemorrhagic fever virus, Lassa fever virus, Marburg virus and Rift Valley fever virus. Laboratory confirmation requires detection of both targets, with confirmation by NML. Specimens with both targets detected are reported as e.g. Zaire ebolavirus RNA detected by PHO laboratory. If a single target is detected, or testing is indeterminate for either target, testing is also repeated at NML. All positive and indeterminate PHO laboratory results are provisional until confirmed by NML.
Sudan ebolavirus PCR assaydetects one gene target – the polymerase (L) gene. This is a laboratory developed test developed by NML. This assay has been verified at PHO's laboratory for clinical testing but is not Health Canada approved. Testing is performed in parallel at NML. Results should be interpreted in the context of the clinical history and other pathological findings.