Archived: Rapid risk assessment: Marburg virus importation into Canada

Assessment completed: October 25, 2024 (based on information available as of October 24, 2024)

On this page

• Reason for assessment
• Risk question
• Risk statement
• Risk assessment summary
  • Future risk for Canada
• Proposed actions for public health authorities
  • Coordination and collaboration
  • Communication
  • Addressing knowledge gaps and uncertainties
• Footnotes

Reason for assessment

Given the current outbreak in Rwanda, there is interest in monitoring the risk of Marburg virus (MARV) importation into Canada and subsequent spread.

Risk question

What is the likelihood that an individual infected with MARV will enter Canada from Rwanda and remain undetected at the border, and the impact of this importation in the next 3.5 months (mid-October 2024 to end of January 2025)?

An assessment timeframe of 3.5 months between mid-October to the end of January was chosen to account for holiday travel and an incubation period for MARV of up to 21 days. If the outbreak in Rwanda is declared over before the end of this timeframe, the risk would decrease for Canada.

Risk statement

The overall risk of MARV to the Canadian population is low, given that the likelihood of importation is very low, coupled with minimal impact on the general population in Canada should a case be imported.

The likelihood of an individual infected with MARV entering into Canada and remaining undetected in the next 3.5 months is very low, given the very low likelihood that the general population^{Footnote a} will be exposed and infected in Rwanda, as well as the very low likelihood that an infected international aid or healthcare worker in Rwanda will travel to Canada. The level of uncertainty ranges from low for the general population to high for international aid and healthcare workers given the key gaps in information on the latter.

If importation were to occur, transmission is expected to be limited to close contacts of the traveller, since outbreak sizes have historically been small and secondary attack rates for those not in direct contact with the virus are low.

The impact of MARV infection on individuals is estimated to be severe with a very low level of uncertainty, given historical evidence from other outbreaks to date.

The impact of an imported MARV infection on the population of close contacts^{Footnote b} of infected individuals is estimated to be moderate, driven by the limited expected transmission and the social implications of medical isolation and quarantine. There is a moderate level of uncertainty due to the range of household secondary attack rates and lack of information regarding case management and contact tracing in historical outbreak data.

The impact of a MARV infection on an affected health care facility in Canada is expected to be major; although transmission is expected to be limited, there will be major impacts driven by the extensive infection prevention measures that would need to be established and the potential impact on a facility's ability to provide care to patients with unrelated ailments. The uncertainty is moderate due to the varying capacity of different healthcare facilities to identify a case early and implement appropriate measures.

If importation were to occur, the impact of MARV infection on the general population in Canada would be minimal, given the limited number of cases expected in Canada. There is a low level of uncertainty in this estimate due to documented modes of transmission from historical outbreak data.

Risk assessment summary

Future risk in Canada

The risk for Canada posed by MARV depends on the nature and extent of the outbreak if it were to change. If the outbreak in Rwanda is declared over, the risk would decrease for Canada. In addition, evidence of effectiveness of the candidate vaccines administered in Rwanda would further reduce the risk associated with future outbreaks of MARV. Conversely, the risk would increase if broader community transmission were to occur in Kigali, or if there was spread to regions outside of those currently affected in Rwanda. This risk could further increase if cases begin to appear in countries with higher travel connections to Canada.

A reasonable worst-case scenario for MARV risk in Canada would involve an imported case not detected at the border, leading to transmission among close contacts and/or within health care settings. This may be more likely to occur if the infected individual develops symptoms after entering Canada. Canada has never had an imported case of Marburg virus disease (MVD) to date and awareness of this disease may be low among healthcare staff, increasing potential for misdiagnosis or delayed diagnosis, and exposure of healthcare workers if patients are managed without appropriate personal protective equipment (PPE). This could potentially lead to further transmission to other patients and staff within a healthcare facility. Awareness among health care professionals about the ongoing outbreak for early detection and diagnosis including travel history, rapid isolation of an imported case, case and contact management, and strict infection prevention and control protocols are critical to mitigate further transmission of the virus. In addition, risk communication is important to counter mis- or disinformation, and to curb the fear of the disease among the general population and health care workers.

Proposed actions for public health authorities

Recommendations provided below are based on findings of this risk assessment. These are for consideration by jurisdictions according to their local epidemiology, policies, resources, and priorities. Due to the current level of uncertainty associated with MVD, it is important that the public health response be proportionate to the risk.

Coordination and collaboration

• Encourage information sharing among public health partners (provincial/territorial, national and global) to contribute to risk assessment and global epidemiological knowledge of this emerging threat to help identify proactive measures to mitigate the risk.
• Collaborate with federal, provincial and territorial partners to build on existing resources, available guidance, and capacity in the acute healthcare and public health sectors for preparedness (i.e., to enable timely diagnosis and patient management, infection prevention and control, and public health management).

Communication

• Consider updating information for travellers to affected regions and refer to PHAC's travel health notice "Marburg virus disease in Rwanda" for information on the current situation and recommendations for travellers.
• Consider engaging the travel industry and travel health clinics in advance of travel to raise awareness of MVD among their clients.

Addressing knowledge gaps and uncertainties

• Consider supporting data collection, science and research activities to address knowledge gaps and contribute to emerging evidence for public health decision making.