The main goal of emerging respiratory virus surveillance is early detection of a case in Canada, and subsequently such virus surveillance informs efforts at containment and/or mitigation of this novel respiratory pathogen. This document outlines surveillance case definitions and provides instructions on reporting to the national level. More detailed information on surveillance guidelines, including recommendations for surveillance objectives, activities, laboratory testing, and reporting of results, are described in the National Surveillance Guidelines for Human Infection with Middle East Respiratory Syndrome Coronavirus (MERS-CoV).
Surveillance case definitions are provided here for the purpose of case classification and reporting to the Public Health Agency of Canada. They are based on the current level of epidemiological evidence and uncertainty, and public health response goals. These surveillance case definitions are not intended to replace clinician or public health practitioner judgment in individual patient management, or intended to be used for the purpose of infection control triage.
It should be noted that unusual severe acute respiratory illness (SARI) clusters in community or facility settings (and notably involving health care workers) should be appropriately investigated under the direction of local and provincial health authorities.
Initial screening tests specific for MERS-CoV can be performed in select laboratories (i.e. provincial public health and hospital-based laboratories); however, confirmation of diagnosis should be sought from Canada's National Microbiology Laboratory (NML) before being considered conclusive . Such cases are considered probable pending NML confirmation. For more information on appropriate specimens or targets for laboratory testing, refer to the Protocol for Microbiological Investigations of Severe Acute Respiratory Infections (SARI).
Provincial / Territorial public health authorities should report confirmed and probable cases of MERS-CoV nationally within 24 hours of their own notification. National surveillance case definitions are provided below - these are subject to change with ongoing monitoring and as understanding of MERS-CoV characteristics and risk evolve.
Person Under investigation (PUI):
Note: The surveillance mechanisms and systems for identifying a PUI may vary by jurisdiction according to perceived risk, resources, supporting structures and other context.Note: Limited data suggests that MERS-CoV can present as a co-infection with other viral pathogens. The identification of one causative agent should not exclude MERS-CoV where the index of suspicion may be high.
Note: Laboratory confirmation not available: due to (a) no possibility of acquiring samples for laboratory testing for MERS-CoV either because the patient or samples are not available; or (b) laboratory diagnosis negative (i.e. negative MERS-CoV result but specimen quality or timing is suspect).
Note:A positive screening test for MERS-CoV should meet one of the following conditions: (1) a positive PCR result for at least two different specific targets on the MERS-CoV genome; OR (2) one positive PCR result for a specific target on the MERS-CoV genome and MERS-CoV sequence confirmation from a separate viral genomic target.
Laboratory findings may take up to 7 days from specimen submission. See additional notes under PUI.
The NML can confirm detection of the virus using MERS-CoV specific nucleic acid amplification tests (NAATs) and/or sequencing and though virus isolation in tissue culture.
Many infectious diseases present with a spectrum of illness, including mild or asymptomatic infection. Atypical MERS-CoV presentation with absent respiratory symptoms has been documented in the presence of comorbidity, notably immuno-suppression. Therefore, clinician and public health judgment should be used in assessing patients with milder or atypical presentations, where, based on contact, comorbidity or cluster history, the index of suspicion may be raised. Additional information can be found in the Interim Guidance For Containment When Imported Cases With Limited Human-To-Human Transmission Are Suspected/Confirmed In Canada.
Clinician discretion, epidemiologic context and local feasibility should be taken into account in discussion with local/provincial health authorities.